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Step by Step
Ultrasound in Obstetrics
Step by Step Ultrasound in Obstetrics
Forthcoming Publications in the Step by Step in Ultrasound Series GYNECOLOGY INFERTILITY COLOR DOPPLER 3D AND 4D ULTRASOUND INTERVENTIONAL ULTRASOUND
Step by Step
Ultrasound in Obstetrics Kuldeep Singh MBBS FAUI FICMCH
Consultant Ultrasonologist Special Interest in Obstetric Sonology in Detailed Anomaly Scanning and Color Doppler for Management and Gynecological Scanning Dr Kuldeep’s Ultrasound and Color Doppler Clinic 266, Prakash Mohalla, East of Kailash New Delhi 110065 (India) Phones: 011-26441720, 26233342 Mobile: 98111 96613 [email protected]
Narendra Malhotra MD FICOG FICMCH Ian Donald Diploma
Practising Obstetrician Gynecologist Special Interest in High-Risk Obstetrics, Ultrasound, Laparoscopy and Infertility, ART and Genetics Malhotra Nursing and Maternity Home Pvt Ltd (India) 84, MG Road, Agra 282010 Phones: 0562-2260275/2260276/2260277 Mobile: 98370 33335 [email protected] www.mnmhagra.com
JAYPEE BROTHERS MEDICAL PUBLISHERS (P) LTD New Delhi
Published by Jitendar P Vij Jaypee Brothers Medical Publishers (P) Ltd EMCA House, 23/23B Ansari Road, Daryaganj New Delhi 110 002, India Phones: 23272143, 23272703, 23282021, 23245672, 23245683 Fax: 011-23276490 e-mail: [email protected] Visit our website: http://www.jpbros.20m.com
Branches • 202 Batavia Chambers, 8 Kumara Kruppa Road Kumara Park East, Bangalore 560 001, Phones: 2285971, 2382956 Tele Fax : 2281761 e-mail: [email protected] • 282 IIIrd Floor, Khaleel Shirazi Estate, Fountain Plaza Pantheon Road, Chennai 600 008, Phone: 8262665 Fax: 8262331 e-mail: [email protected] • 4-2-1067/1-3, 1st Floor, Balaji Building Ramkote Cross Road, Hyderabad 500 095 Phones: 6590020, 4758498 Fax: 4758499 e-mail: [email protected] • 1A Indian Mirror Street, Wellington Square Kolkata 700 013, Phone: 2451926 Fax: 2456075 e-mail: [email protected] • 106 Amit Industrial Estate, 61 Dr SS Rao Road Near MGM Hospital, Parel, Mumbai 400 012 Phones: 24124863, 24104532 Fax: 24160828 e-mail: [email protected] Step by Step Ultrasound in Obstetrics © 2004, Kuldeep Singh, Narendra Malhotra All rights reserved. No part of this publication should be reproduced, stored in a retrieval system, or transmitted in any form or by any means: electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the authors and the publisher. This book has been published in good faith that the material provided by authors is original. Every effort is made to ensure accuracy of material, but the publisher, printer and authors will not be held responsible for any inadvertent error(s). In case of any dispute, all legal matters are to be settled under Delhi jurisdiction only.
First Edition : 2004 ISBN 81-8061-203-1 Typeset at JPBMP typesetting unit Printed at Replika Press Pvt Ltd., 310 EPIP, HSIDC, Kundli, Sonepat (Haryana)
Preface Today ultrasound is the mainstay investigation in all fields of medicine. The wide spread use of ultrasound has brought this wonderful technology to the consulting rooms of the practising gynecologists. It is now impossible to even conceive a modern obstetric care unit without ultrasound and it is impossible to practise infertility and gynecology without a transvaginal probe which has added the dimension of imaging with palpation. The law in India mandates that each machine and the sonologist be licensed to practise ultrasound under the PNDT Act for which training and updating is required. There are numerous textbooks and reference books on ultrasound but our aim to bring out this handy series of Step by Step Ultrasound in Obstetrics is to simplify the indications and the steps and the interpretations of this wonderful technology. We hope the readers will be benefited by this book. Kuldeep Singh Narendra Malhotra
Acknowledgements Thanks to our parents, elders, teachers, spouses, siblings, our sons and daughters and friends, who help and encourage whenever you undertake a mammoth project. To write any book without help is impossible. We are grateful to: Prof. Stuart Campbell, Prof. Asim Kurjak, Late Prof M.Y. Rawal, Prof. C.S. Dawn, Dr. S.Suresh, Dr. Arun Kumar, Dr. P.K. Shah, Dr. Bhupendra Ahuja, Dr. R.N.Bagga, Dr. Ashok Khurana, Dr. Jatin P Shah, Dr. Pranay Shah and many others who have helped and taught us at each step of our life. We are extremely grateful to our wives Mrs. Nishu K. Singh and Dr. Jaideep Malhotra, for the unflinching support and help in all our efforts and for tolerating all our moods and ideas. Our children Jaanvi Sana Chhabra, Ramanjeet Singh, Neharika Malhotra (Medical student), and Keshav Malhotra. God bless them. Grow up and do well.
Contents 1. Introduction 1.1 Filling up of forms 1.2 Relevant history 1.3 Preparation and positioning of patient 1.4 Machine and transducers 1.5 Reporting 2. Training 2.1 Theoretical aspects 2.2 Training parameters 2.3 Suggested training schedule 2.4 Prerequisite criteria for a trained ultrasonologist 2.5 Mandatory proposed certification for an ultrasonologist (Obs. and Gyn.) 3. First Trimester 3.1 Indications 3.2 Normal first trimester embryonic/fetal evaluation 3.3 Normal parameter evaluation in the first trimester 3.4 Abnormal intrauterine pregnancy 3.5 Impending early pregnancy failure 3.6 Ectopic gestation
1 1 1 2 3 4 8 8 9 10 11 12 14 14 15 23 23 23 28
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Step by Step Ultrasound in Obstetrics
3.7 Extra fetal evaluation 3.8 Abnormal intrauterine pregnancy forms 3.9 Complete abortion 3.10 Incomplete abortion 3.11 Molar change 3.12 Sono-embryology chart 3.13 Abnormal fetus 3.14 First trimester scan check list 3.15 Dilemmas 3.16 First trimester key points 3.17 Transvaginal decision flow chart 4. Second Trimester 4.1 Indications 4.2 Fetal evaluation 4.3 Fetal evaluation (malformations) 4.4 Cranium 4.5 Nuchal skin 4.6 Fetal orbits and face 4.7 Fetal spine 4.8 Fetal thorax 4.9 Fetal heart 4.10 Fetal abdomen 4.11 Fetal skeleton 4.12 Fetal biometry 4.13 Extra-fetal evaluation 4.14 Color Doppler in second trimester 4.15 3D and 4D scan
33 33 33 33 39 41 48 48 51 51 52 54 54 55 56 56 56 57 78 78 93 93 119 119 119 135 135
Contents xi
4.16 Abnormal second trimester 4.17 Dilemmas 5. Third Trimester 5.1 Indications 5.2 Fetal evaluation 5.3 Extra-fetal evaluation 5.4 Placental check list 5.5 Amniotic fluid assessment 5.6 Causes of oligohydramnios 5.7 Causes of polyhydramnios 5.8 Fetal growth 5.9 Fetal surveillance or fetal wellbeing 5.10 Biophysical profile 5.11 Evaluation by biophysical profile 5.12 Interpretation of biophysical profile 5.13 Serial evaluation 5.14 Color Doppler 5.15 Indications for color Doppler 5.16 Interpretation of the waveforms 5.17 Indications of delivery 5.18 Mode of delivery 5.19 Abnormal third trimester 5.20 Check list 5.21 Dilemmas Index
136 136 137 138 138 138 145 145 147 147 148 149 150 151 151 152 153 153 153 162 162 163 163 163 165
One
1.1 1.2 1.3 1.4 1.5
Introduction Filling up of forms Relevant history Preparation and positioning of patient Machine and transducers Reporting
1.1 FILLING UP OF FORMS Maintain a form for further follow up in your clinic. One never knows when the information is required. The routine information required in these forms is: a. Name b. Age c. Address d. Telephone Number e. Referred by f. PNDT Act Form ‘F’ as required by Government of India Law g. Undertaking by patient and doctor for obstetric ultrasound with Form ‘F’. 1.2 RELEVANT HISTORY Always spend few minutes with your patient to take the details of the history. Gives confidence to the patient and you get your perspective of what all to expect. The history to be taken routinely is :a. Previous obstetric history consisting of details of
2 Step by Step Ultrasound in Obstetrics
b. c. d. e. f.
any abortions (spontaneous or missed), any second or third trimester losses (possible reasons), any previous deliveries (vaginal or cesarian). Try and look into the previous records which can throw any light. Any symptoms in this pregnancy. Any ultrasound done so far in this pregnancy. Check the records carefully. Last menstrual period and regularity of menstrual cycles. Any tests done and their reports. Referring doctors requissition slip (This is now a legal requirement with Form ‘F’).
1.3 PREPARATION AND POSITIONING OF PATIENT 1. In scans upto 15 weeks a full bladder is required, unless transvaginal. It is preferable to examine upto 12 weeks by a transvaginal scan. 2. Between 15 and 22 weeks holding urine for one hour is sufficient. 3. After 22 weeks no preparation is required. A full bladder for assessment of the cervix and lower segment assessment can be asked for when required. 4. The patient need not be fasting unless and until an upper abdomen scan is also asked for. 5. The patient is almost always scanned supine with plenty of jelly on the abdomen. In certain cases scanning in the lateral position (if patient is uncomfortable lying supine or fetus moves when lying in a lateral position) or with the patient standing (for functional assessment of cervix) is required.
Introduction 3
6. Whenever, a transvaginal scan is asked for the bladder must be emptied immediately before the examination. It should be performed with the same respect for privacy and gentleness, as is with the placement of a speculum. Scanning is performed with the patient supine and with her thighs abducted and knees flexed. Elevation of the buttock may be necessary. The probe should be covered with a condom or sheath containing a small amount of gel. Additional gel should be placed on the outside of sheathed tip. The probe is inserted by a gentle push posteriorly towards the rectum while the patient relaxes. Four types of probe movements are required : i. Pushing and Pulling ii. Rotation iii. “Rocking” or upwards and downwards iv. Side to side or “Panning”. After removal of the transvaginal probe, the sheath is removed and the coupling gel is wiped off with a damp towel. The TV probe may be disinfected by Cidex. 1.4 MACHINE AND TRANSDUCERS 1. For a transabdominal scan, a 3.5 to 5.0 MHz transducer and for a transvaginal scan, a 5.0 to 8.0 MHz transducer is used. 2. Basic controls of every machine are more or less the same. The placement of knobs is different for all machines. Check for the manual of your machine or somebody from the company can always come and explain you. The routine knobology is:a. Patient name and entry of last menstrual period after you select the obstetric mode.
4 Step by Step Ultrasound in Obstetrics b. c. d. e. f. g. h.
Freeze B, B+B, B+M or only M mode Depth and focus Overall gain Time gain (T.G.C.) Comments on screen Measurement (Set and Select) for linear, area and volume. i. Track ball or screen or joy stick to move the cursor j. Color flow map, Power Doppler, Doppler and 3D and 4D. k. After freezing the images these can be stored and a print taken on a camera, thermal printer or from a computer. 1.5 REPORTING Maximum possible information to be given in the report to the patient. Routinely four ultrasounds should be asked for in all pregnancies. The parameters to be checked in all four ultrasounds are mentioned. They are: FROM 06-09 WEEKS • • • • • • • •
Uterine size Location of gestational sac Number of gestational sacs Size of gestational sac Yolk sac Size of yolk sac Embryo/fetus size Menstrual age
Introduction 5
• • • • • •
Cardiac activity Heart rate Trophoblastic reaction Any uterine mass Any adnexal mass Corpus luteum (present/absent)
FROM 10-14 WEEKS • • • • • • • • • • • • •
Placental site Liquor amnii Fetal crown rump length Menstrual age Fetal movements and cardiac activity Any gross anomalies Nuchal translucency Nasal bone (Present/absent) Ductus Venosus flow Internal os width Length of cervix Any uterine mass Any adnexal mass
FROM 18-22 WEEKS • • • • • • • •
Placenta Liquor amnii Umbilical cord Cervix Lower segment Myometrium Adnexa Nuchal skin thickness
6 Step by Step Ultrasound in Obstetrics • • • • • • • • • • • • • • • • • •
Cerebellar transverse diameter Cisterna magna depth Width of body of lateral ventricle Inter-hemispheric distance Ratio of the width of body of lateral ventricle to inter-hemispheric distance Ocular diameter Interocular distance Binocular distance Bi-parietal diameter Occipito frontal distance Head perimeter Abdominal perimeter Femoral length Humeral length Foot length Fetal movements and cardiac activity Ductus venosus flow velocity waveform Both maternal uterine artery Doppler
FROM 35-40 WEEKS • • • • • • • • • •
Placenta Liquor amnii Umbilical cord Cervix Lower segment Myometrium Adnexa Bi-parietal diameter Occipito frontal distance Head perimeter
Introduction 7
• • • • •
•
Abdominal perimeter Femoral length Distal femoral epiphysis Biophysical profile/ Modified Biophysical Profile (AFI and VAST) Color Doppler arterial (Umbilical artery, middle cerebral artery, descending aorta and both maternal uterine arteries) Color Doppler venous (Umbilical vein, inferior vena cava and ductus venosus)
Two
Training
2.1 2.2 2.3 2.4
Theoretical aspects Training parameters Suggested training schedule Prerequisite criteria for a trained ultrasonologist 2.5 Mandatory proposed certification for an ultrasonologist (Obs. and Gyn.)
The practice of ultrasound and the use of diagnostic and interventional ultrasound is now a necessary tool rather than a luxury. It is impossible to even conceive an Obstetric Care Unit and Fetal Medicine Unit or even Gynecology and Infertility Diagnostic Unit without ultrasound. To practise ultrasound in India it is mandatory to be trained in ultrasonography under proper guides and to do 100 cases minimum of Obs. Gyn. Ultrasound and 6 months of observership under a Radiologist or an approved centre. 2.1 THEORETICAL ASPECTS The theoretical aspects one should know, should cover topics on Physics of ultrasound, ultrasound machines and probes, how to use an ultrasound machine, PNDT Act, laws of ultrasound, medicolegal aspects, methodology, patient preparations, complete obstetric ultrasound uses including use in first, second and third trimesters, diagnosis of
Training 9
threatened abortion, ectopic pregnancy, biometery, anomaly scanning, IUGR, placental evaluation, amniotic fluid evaluation, color doppler uses and 3D and 4D ultrasound. Complete gynecological ultrasound aspects include use of TVS, color and 3D in evaluating female pelvis and evaluating infertility and complete interventional procedures. 2.2 TRAINING PARAMETERS FIRST LEVEL (At least 30 hours a week for two months) These are aimed at:1. Confirm intrauterine pregnancy. 2. Confirm viability. 3. Determine number of gestations. 4. Fetal biometry. 5. Assessment of growth. 6. Presentation. 7. Amniotic fluid assessment. 8. Placental assessment. 9. Cervix measurement. 10. Suspect abnormalities. SECOND LEVEL (About 100 sessions and 300 hours) These are aimed at:1. Detect and specify early pregnancy problems. 2. Detect and specify abnormalities. 3. Assessment of growth restriction. 4. Fetal biophysical profiling.
10 Step by Step Ultrasound in Obstetrics 5. Understanding Color Doppler. 6. Accurately sampling various blood vessels by Doppler and analysing them. 7. Knowledge of interventional procedure. 8. Knowledge of 3-D and 4-D. 9. Analysis of malignancies. THIRD LEVEL (3 years) These are aimed at: 1. Acquiring 3-D and 4-D image. 2. Perform interventional procedures. 3. Research and development. 4. Ability to teach basic stalls. 2.3 SUGGESTED TRAINING SCHEDULE Viable pregnancies 10 Nonviable pregnancies 10 Normal biometry 10 Growth restrictions 10 Abnormal pregnancy 10 (Ectopic/Multiple etc.) Color Doppler studies obstetric 10 Gynaec 10 IUCD’s 5 Fibroids 10 Ovarian cysts 10 Gynaec disorders 10 Transvaginal scan 10 These are minimum number of scans for Level-I training. Another 100 cases of detailed Obstetric and Gynecological cases for various indications including color and 3-D should be logged for Level-II training.
Training 11
A standard reporting format for gynecology and Obstetrics should be adhered to with details of different descriptive terminology. 2.4 PREREQUISITE CRITERIA FOR A TRAINED ULTRASONOLOGIST 1. The ultrasonologist should be able to identify early pregnancy and emergency gynecological problems by transvaginal and transabdominal ultrasound. a. Early pregnancy: • Fetal viability; • Description of the gestational sac, embryo, yolk sac; • Single and multiple gestation (chorionicity). b. Pathology: • Early pregnancy failure; • Ectopic pregnancy; • Gross fetal abnormalities such as nuchal translucency, hydropic abnormalities; • Hydatidiform mole; • Associated pelvic tumors. c. Gynecology: • Normal pelvic anatomy; • Uterine size and endometrial thickness; • Measurement of ovaries; • Pelvic tumors, e.g., fibroids, cysts hydrosalpinx; • Peritoneal fluid; • Intrauterine contraceptive devices. 2. The ultrasonologist should be able to recognise the following normal fetal anatomical features from 18 weeks onwards by abdominal ultrasound.
12 Step by Step Ultrasound in Obstetrics a. b. c. d. e.
Shape of the skull: nuchal skinfold; Brain: ventricles and cerebellum, choroid plexus; Facial profile; Spine: both longitudinally and transversely; Heart rate and rhythm, size and position, fourchamber view; f. Size and morphology of the lungs; g. Shape of the thorax and abdomen; h. Abdomen: diaphragm, stomach, liver and umbilical vein, kidneys, abdominal wall and umbilicus; i. Limbs: femur, tibia and fibula, humerus, radius and ulna, feet and hands—these to include shape, echogenicity and movement; j. Multiple pregnancy: monochorionic and dischorionic, twin-twin transfusion syndrome; k. Amount of amniotic fluid; l. Placental location; m. Cord and number of vessels. 3. Fetal biometry a. Crown rump length, biparietal diameter, femur length, head circumference, abdominal circumference, interpretation of growth charts. 4. Activity: recognize and quantify a. Fetal movements; b. Breathing movements; c. Eye movements. 2.5 MANDATORY PROPOSED CERTIFICATION FOR AN ULTRASONOLOGIST (OBS AND GYN) 1. One hundred hours in 6 months, of supervised scanning to include (one year observership):
Training 13
a. 100 gynecological examinations and early pregnancy problems (principally by transvaginal sonography but transabdominal experience also required). b. 200 obstetric scans covering the full spectrum of obstetric conditions. 2. Logbooks: 30 cases on one A4 page with ultrasound picture, at least 15 anomalies should be included. These are suggested training hours and comply with the Indian Government’s requirement under the modified PNDT Act.
Three
First Trimester
3.1 Indications 3.2 Normal first trimester embryonic/fetal evaluation 3.3 Normal parameter evaluation in the first trimester 3.4 Abnormal intrauterine pregnancy 3.5 Impending early pregnancy failure 3.6 Ectopic gestation 3.7 Extra fetal evaluation 3.8 Abnormal intrauterine pregnancy forms 3.9 Complete abortion 3.10 Incomplete abortion 3.11 Molar change 3.12 Sono-embryology chart 3.13 Abnormal fetus 3.14 First trimester scan checklist 3.15 Dilemmas 3.16 First trimester key points 3.17 Transvaginal decision flow charts 3.1 INDICATIONS 1. Confirmation of pregnancy 2. Vaginal bleeding in pregnancy (Threatened abortion)
First Trimester 15
3. 4. 5. 6. 7. 8.
Estimation of gestational age Suspected ectopic pregnancy Suspected hydatidiform mole Adjunct to cervical cerclage Suspected multiple gestation Adjunct to chorionic villus sampling
3.2 NORMAL FIRST TRIMESTER EMBRYONIC/ FETAL EVALUATION 1. Location of sac a. Fundus (Fig. 3.1) b. Corpus (Fig. 3.2) c. Cornual (Fig. 3.3) d. Superior to the cervix 2. Number of sacs a. Single b. Multiple (Twin/Triplet/High Order Multiple) (Fig. 3.4) 3. Size of sac a. In toto, measure inner to inner diameter of gestational sac on all three sides and calculate the size and corresponding gestational age (Fig. 3.5). b. Size of gestational sac in comparison to the embryo/fetus size (Fig. 3.6) 4. Embryo/fetal size (Crown rump length) (Figs 3.7 and 3.8) 5. Embryonic cardiac activity. To begin with, the heart rate is around 85 beats/ minute at 5 to 5½ weeks (Fig. 3.9) increasing to around 160 beats/minute (Fig. 3.10) at nine weeks
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Step by Step Ultrasound in Obstetrics
Fig. 3.1: Gestational sac located in the uterine fundus
6. Yolk sac a. Size b. Shape c. Any calcification
Fig. 3.2: Gestational sac located in the uterine corpus
First Trimester 17
Fig. 3.3: Gestational sac located in the uterine cavity in the cornual area. Note the amount of myometrium lateral to the gestational sac differentiating it from a cornual ectopic
Fig. 3.4: Two gestational sacs both located in the uterine fundus
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Step by Step Ultrasound in Obstetrics
Fig. 3.5: Gestational sac measurement in all three planes and calculation of gestational age done by the ultrasound machine
7. Trophoblastic reaction a. Whether wrapping around and thick reaction (Fig. 3.11) b. Locate site (Fig. 3.12) 8. Separation a. Amnio-decidual separation (Fig. 3.13) b. Chorio-decidual separation (Fig. 3.14)
Fig. 3.6: Note that the sac is oligoamniotic with the gestational sac corresponding less than the embryo size
First Trimester 19
Fig. 3.7: Measurement of crown rump length in a 7 weeks and 6 days embryo
Fig. 3.8: Measurement of crown rump length in an 11 weeks and 6 days fetus
9. To identify any gross anomalies a. Gross abnormalities of the cranium, spine, abdomen and limbs can be detected even in the late first trimester.
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Step by Step Ultrasound in Obstetrics
Fig. 3.9: Heart rate of 92 beats per minute in a 5 weeks and 5 days embryo
Fig. 3.10: Heart rate of 174 beats per minute in an 8 weeks and 1 day fetus
b. Nasal bone ossification c. Nuchal Translucency
First Trimester 21
Fig. 3.11: Wrapping around thick trophoblastic reaction seen in a gestational sac of 6 weeks 5 days
Fig. 3.12: Note the thickened trophoblastic echoes (star) on one wall of the gestational sac. This is the placental site location
10. Color Doppler evaluation of the ductus venosus and both maternal uterine arteries
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Step by Step Ultrasound in Obstetrics
Fig. 3.13: The placenta is anterior with an amnio-decidual separation seen in the anterior wall superior to the cervix. This has an associated collection of 8.35 ml
Fig. 3.14: Multiple foci of chorio-decidual separation seen in a 06-07 weeks size missed abortion
First Trimester 23
3.3 NORMAL PARAMETER EVALUATION IN THE FIRST TRIMESTER 1. Gestational sac seen as early as 4½ weeks by transvaginal scan and 5½weeks by transabdominal scan (Fig. 3.15) 2. Yolk sac: seen as early as 5 weeks by transvaginal scan and 6 weeks by transabdominal scan (Fig. 3.16) 3. Embryo: seen at 5½ weeks by transvaginal scan and at 6-6½ weeks by transabdominal scan (Fig. 3.17) 4. Cardiac activity: appears at 5 weeks and 4 days 3.4 ABNORMAL INTRAUTERINE PREGNANCY 1. No embryonic cardiac activity with a CRL > 5 mm. (Missed Abortion) (Fig. 3.18) 2. Gestational sac larger than 8 mm without a yolk sac. (Blighted Ovum) (Fig. 3.19) 3. Gestational sac larger than 16 mm without an embryo. (Anembryonic Pregnancy) (Fig. 3.20) 4. Abnormally large or irregular or small amniotic sac (Fig. 3.21) 3.5 IMPENDING EARLY PREGNANCY FAILURE 1. Embryonic bradycardia relative to CRL 2. Mean sac diameter minus CRL is less than 5 mm (oligoamniotic sac) 3. Poor sac growth 4. Large (> 5.6 mm prior to 10 weeks) /abnormal yolk sac (Figs 3.22 and 3.23) 5. Disappearance of the corpus luteum
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Step by Step Ultrasound in Obstetrics
Fig. 3.15: Transvaginal scan of a gestational sac of 05 weeks size
Fig. 3.16: Gestational sac of 5 weeks and 2 days with a yolk sac clearly delineated (solid line)
Classification of Early Pregnancy Loss Stage A • Loss withing first 2 weeks
First Trimester 25
Fig. 3.17: Pregnancy of 5 weeks and 6 days gestation showing a yolk sac (solid line) and an embryo (dotted line)
Fig. 3.18: No cardiac activity seen in this 08 mm pulseless attenuated embryo
• •
Subclinical loss No sonographic evidence
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Step by Step Ultrasound in Obstetrics
Fig. 3.19: Thin-walled gestational sac of 15 mm in the uterine fundus with no embryo or yolk sac seen
Fig. 3.20: Seven weeks gestational sac showing a yolk sac but no embryo
Stage B • Loss at 05-06 weeks • Empty gestational sac
First Trimester 27
Fig. 3.21: Large, flaccid and irregular amniotic sac with a pulseless embryo
Fig. 3.22: Large yolk sac with the embryo seen adjacent to it
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Step by Step Ultrasound in Obstetrics
Fig. 3.23: Shrunken yolk sac with an extensive cystic hygroma associated with it
Stage C • Loss at 07-08 weeks • Abnormal gestational sac and embryo Stage D • Loss at 09-12 weeks • Abnormal embryo 3.6 ECTOPIC GESTATION 1. Demonstration of live embryo in the adnexa is diagnostic of ectopic pregnancy (Fig. 3.24) 2. Nonspecific findings of an ectopic pregnancy are an adnexal mass (Fig. 3.23), free fluid (Fig. 3.25), a tubal ring (Fig. 3.26) and identification of adnexal peritrophoblastic flow (Fig. 3.27) 3. Vascular ring can be delineated (Fig. 3.28) 4. The blood flow characteristically shows lowimpedance, high-diastolic flow
First Trimester 29
Fig. 3.24: Live ectopic with a gestational sac, yolk sac and an embryo with cardiac activity
Fig. 3.25: Left adnexal mass with corpus luteum in the left ovary with an adjacent inhomogeneous adnexal mass and peri-lesional fluid collection
5. Intrauterine peri-trophoblastic flow is not seen and periendometrial venous flow is also very less 6. Corpus luteal flow is identified in one or both ovaries
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Step by Step Ultrasound in Obstetrics
Fig. 3.26: Adnexal mass with free fluid (pelvic hematocele) in the pouch of Douglas
Fig. 3.27: On color Doppler in an ectopic pregnancy which is unruptured with viable trophoblasts a vascular ring is delineated with the blood flow characteristically showing low-impedance, high-diastolic flow
First Trimester 31
Fig. 3.28: Same case with marked peri-trophoblastic vascularity in the mass
Fig. 3.29: Look for any masses in the myometrium. Early pregnancy with a posterior wall subserous fibroid. If you locate any fibroid specify the site (uterine or cervical) and the type (submucous, interstitial, subserous or panmural) so as to assess later in serial scans
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Step by Step Ultrasound in Obstetrics
Fig. 3.30: Even in the first trimester always evaluate the cervical length by measuring from the cervical waist or the location of the internal os till the portion where the mucus plug ends. Any herniation or shortening to be reported for serial evaluation
Fig. 3.31: Apart from the corpus luteum always evaluate the adnexa for any masses like dermoid, broad ligament fibroid or any other ovarian masses
First Trimester 33
3.7 EXTRA FETAL EVALUATION 1. 2. 3. 4. 5. 6.
Myometrium (Fig. 3.29) Cervical length (Fig. 3.30) Internal os Adnexal mass (Fig. 3.31) Site of corpus luteum (Fig. 3.32) Vascularity of corpus luteum (Figs 3.33 and 3.34)
3.8 ABNORMAL INTRAUTERINE PREGNANCY FORMS 1. 2. 3. 4. 5.
Threatened/missed abortion Incomplete abortion Complete abortion Hydatiform mole Blighted ovum
3.9 COMPLETE ABORTION 1. No intrauterine gestational sac seen (empty uterus sign) 2. Cavity echoes are thin and usually homogeneous (Fig. 3.35) 3. Uterine vascularity is cold or warm (Fig. 3.36) 4. There is minimal or absent intrauterine peritrophoblastic flow (Fig. 3.37) 5. Intrauterine venous flow is minimal or absent 3.10 INCOMPLETE ABORTION 1. Inhomogeneous cavity echoes (Fig. 3.38) 2. Overall uterine vascularity diffusely increased (warm or hot vascularity) (Fig. 3.39)
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Step by Step Ultrasound in Obstetrics
Fig. 3.32: Locate the corpus luteum as to which ovary it is in. Corpus luteum can appear iso- or hypoechoic within the ovary depending on hemorrhage
Fig. 3.33: On color flow mapping one can assess the vascularity of the corpus luteum
3. Peri-trophoblastic arterial flow present with high systolic velocities (Fig. 3.40)
First Trimester 35
Fig. 3.34: Evaluate the vascularity of the corpus luteum by color flow mapping and the arterial flow velocity waveform on duplex Doppler should normally show a resistive index of less than 0.55
Fig. 3.35: A case of complete spontaneous abortion with very thin cavity echoes, 03-04 mm
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Step by Step Ultrasound in Obstetrics
Fig. 3.36: The uterine vascularity is usually cold in a case of complete spontaneous abortion
Fig. 3.37: Intrauterine peri-trophoblastic flow is not seen and only peripheral myometrial vascularity seen
4. Peri-endometrial venous flow also increased (Fig. 3.41)
First Trimester 37
Fig. 3.38: Inhomogeneous echoes within the uterine cavity seen on 2D Ultrasound in a case of amenorrhea 6 weeks with bleeding for 3 days
Fig. 3.39: Case of missed abortion seen on 2D Ultrasound and on color Doppler, the overall uterine vascularity is increased (warm or hot vascularity)
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Step by Step Ultrasound in Obstetrics
Fig. 3.40: Same case on duplex Doppler evaluation the peritrophoblastic arterial flow is identified, with systolic velocities much above the normal range for intrauterine pregnancy
Fig. 3.41: Case of missed abortion with increased peri-endometrial venous flow
First Trimester 39
3.11 MOLAR CHANGE 1. Echogenic tissue interspersed with numerous punctate sonolucencies (snow storm appearance) (Figs 3.42 and 3.43) 2. In uncomplicated cases only mild increase in perilesional vascularity is noted 3. In invasive moles very high velocity flow in areas of tumor invasion within the myometrium are seen (Fig. 3.44) 4. Very low impedance flow with almost an arteriovenous shunt type waveform is also seen 5. Hypervascularity recedes with regression of the tumor
Fig. 3.42: Characteristic cystic spaces packed in the uterine cavity are seen in this case of molar pregnancy
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Step by Step Ultrasound in Obstetrics
Fig. 3.43: Nonviable gestational sac with thin-walled clear cystic spaces around the gestational sac
Fig. 3.44: In molar pregnancy in uncomplicated cases only mild increase in peri-lesional vascularity is noted. In invasive moles very high velocity flow in areas of tumor invasion within the myometrium are seen. Very low impedance flow with almost an arteriovenous shunt type waveform is also seen. This hypervascularity recedes with regression of the tumor
First Trimester 41
3.12 SONO-EMBRYOLOGY CHART (Figs 3.45-3.55) Date
Event
Sonological evaluation
Day 14
Ovulation
Day 15 Day 18
Fertilization Morula Stage
Day 22-23 Day 23 Day 26-28
Blastocyst Primary Yolk Sac Extra Embryonic Coelom Secondary Yolk Sac Syncytiotrophoblast and Sometimes seen Chorionic Cavity Gastrulation
Collapse of Follicle, Free fluid, Corpus luteum, Secretory endometrium Decidualization of Endometrium Implantation window Implantation Site Implantation site recognition
Day 27-28 Day 28
Week 5 29/30 31/42
Neuralisation
34/44
Somites
Weeks 6-12
Cardiovascular System Unidirectional Blood flow Heart/ Peripheral vascular System
6 weeks 8 weeks 10 weeks
Visualization of Gestational Sac, and secondary, Yolk Sac Growth of sac Embryo Fetal cardiac activity Embryo visualization Crown rump length Cardiac activity
Cardiac activity Seen by TVS Visualized Contd...
42
Step by Step Ultrasound in Obstetrics
Contd...
6 weeks 8-12 weeks
8 weeks 11 weeks 14 weeks 6 weeks 8 weeks 9 weeks 10 weeks 10 weeks 11 weeks 11 weeks
Gastrointestinal Tract Primitive Gut Gut lies outside Physiological herniation in umbilical cord Genitourinary Primitive kidney Not yet seen Kidney develops Seen urine production Bladder seen External genitalia Can be seen Musculoskeletal System Limb buds Can be seen Digital rays Can be seen Clavide ossification Seen Mandible ossification Seen Nasal bone ossification Seen Spinal ossification Spine seen Frontal bones Long bone ossification
Fig. 3.45: Anechoic areas (solid lines) seen in the brain of a fetus of 9 weeks and 6 days
First Trimester 43
Fig. 3.46: Upper and lower limbs (solid lines) seen
Fig. 3.47: Cerebellar hemispheres (arrows) with deficiency in the vermis (physiological at this stage)
44
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Fig. 3.48: Echogenic choroid plexii (stars) in the lateral ventricles
Fig. 3.49: Fetal spine can be seen as two parallel lines
First Trimester 45
Fig. 3.50: Physiological herniation (solid lines) of bowel seen below the umbilical cord
Fig. 3.51: Fetal stomach bubble seen in a fetus of 11 weeks and 4 days
46
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Fig. 3.52: Fetal kidney seen as an echogenic structure adjacent to the fetal spine
Fig. 3.53: Fetal urinary bladder seen in a fetus of 12 weeks and 2 days
First Trimester 47
Fig. 3.54: Extensive cystic hygroma (arrow heads) in a 10 weeks and 1 day fetus
Fig. 3.55: Orbits (solid lines) delineated as early as 11 weeks. Measure the ocular diameter, interocular distance and binocular distance to diagnose hypotelorism. Visualization of both orbits excludes anophthalmia or single orbit deformity
48
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3.13 ABNORMAL FETUS 1. Fetal abnormalities like Acrania (Fig. 3.56), Anencephaly (Fig. 3.57), Limb reduction defects, Gross anterior abdominal wall defects can be diagnosed in the late first trimester 2. Nasal bone ossification (Fig. 3.58) being absent can be diagnosed in the first trimester to raise the suspicion of chromosomal abnormalities. 3. Thickened nuchal translucency (Fig. 3.59) can again raise the suspicion of chromosomal abnormalities and one can go in for early amniocentesis or biochemical markers to diagnose them. If nuchal translucency thickness resolves it does not indicate normalcy and on an amniocentesis if karyotype is normal subject the fetus to an echocardiography as an increased nuchal translucency thickness can denote a cardiac abnormality as well. 3.14 FIRST TRIMESTER SCAN CHECK LIST 1. LMP and gestation 2. Identify uterus and gestational sac do not hesitate to do a transvaginal scan 3. Confirm viability and number 4. Look at the cervix and implantation site 5. Check adnexa 6. Measure embryo 7. Give a sonological gestational age and EDD and verify with LMP 8. Give a complete structured report with hard copy of pictures
First Trimester 49
Fig. 3.56: Case of Acrania with only brain and no bone seen superior to the orbits
Fig. 3.57: Case of Anencephaly with no brain or bone seen superior to the orbits
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Fig. 3.58: Nasal bone ossification being present or absent is a marker for Trisomies especially Trisomy 21
Fig. 3.59: Nuchal translucency in a 10 weeks fetus. Any thickening of the nuchal translucency prompts to a diagnosis of cystic hygroma, chromosomal abnormalities or cardiac abnormalities
First Trimester 51
3.15 DILEMMAS 1. Overdue: ultrasound or urine test. Urine test is positive before a gestational sac can be seen on an ultrasound scan 2. Urine test negative: ultrasound y/n. Definitely to rule out any ectopic gestation and to confirm the cause for the delayed period 3. Miscarried last time: should ultrasound be done. To be done to insure fetal well being and to discern any cause on ultrasound for recurrent pregnancy loss 4. Pain abdomen: ectopic will be definitely ruled out by ultrasound normally some or the other sign of ectopic pregnancy can be seen on an ultrasound scan, but many a times with overlapping nonspecific signs it can also be missed 3.16 FIRST TRIMESTER KEY POINTS • • • • •
• •
CRL = 10 mm = mean for 7 weeks CRL = 30 mm = mean for 9 weeks 5 days CRL = 60 mm = mean for 12 weeks 3 days A viable intrauterine pregnancy practically rules out ectopic gestation. (Except one in 30000) There is a delay of identifying of one week by transabdominal as compared to transvaginal Sac (2-4 mm) 4.5 weeks 5.5 weeks Fetal heart (CRL2-4) 5 weeks 6 weeks Yolk sac (10 mm) 5 weeks 6 weeks Early fetal bradycardia signifies poor prognosis Fetal chromosomal anomalies can be screened for and detected in the 10-14 weeks scan
52 • •
• •
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Transvaginal scan does not increase abortion risk of bleeding A thorough knowledge of fetal embryology and implantation and corpus luteum physiology is a must for first trimester diagnosis Do not hesitate to take second opinion 20 mm sac with no intra sac structures is suggestive of anembryonic pregnancy. A CRL of > 6 mm without fetal heart is suggestive of missed abortion. Confirm by TVS and repeat scan if required.
3.17 TRANSVAGINAL DECISION FLOW CHART Failed pregnancy No embryo seen Sac size <16 mm
Sac size >16 mm
Missed abortion Yolk sac present
Follow-up after 1 week
Late conception
Yolk sac absent
Gestational sac < 08 mm
Gestational sac >08 mm
Missed abortion
First Trimester 53
DECISION MAKING IN THE FIRST TRIMESTER Embryo visualized
Cardiac activity present
CRL >05 mm
Yolk sac present
Cardiac activity absent
CRL <05 mm
CRL >05 mm
CRL <05 mm
Yolk sac absent Follow-up after one week
Normal
Abnormal
Close followup after 1 week CRL >05 mm
Heart rate normal
CRL < 05 mm
Heart rate abnormal
Missed Appearance abortion of fetal heart
Normal Abnormal
D&C Detailed 11-14 weeks scan 20 weeks scan
Late conception
Four 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.17
Second Trimester Indications Fetal evaluation Fetal evaluation (malformations) Cranium Nuchal skin Fetal orbits and face Fetal spine Fetal thorax Fetal heart Fetal abdomen Fetal skeleton Fetal biometry Extra-fetal evaluation Color Doppler in second trimester 3D and 4D scan Abnormal second trimester Dilemmas
4.1 INDICATIONS 1. Follow-up observation of identified fetal anomaly or history of previous congenital anomaly 2. Adjunct to amniocentesis 3. Abnormal serum alpha-fetoprotein value 4. Suspected polyhydramnios or oligohydramnios 5. Advanced maternal age
Second Trimester 55
6. Exposure to drugs/radiation 7. Maternal diabetes mellitus 8. Bad obstetric history Scanning is done with a fully distended maternal bladder, though this is not essential after 20 weeks. 4.2 FETAL EVALUATION 1. 2. 3. 4. 5. 6.
Number Fetal position especially in the late second trimester. Viability Movements Gestational age Biometry
Fig. 4.1: Section for cranial biometry consisting of the thalamus, the third ventricle and the cavum septum pellucidum. The biparietal diameter is the side to side measurement from the outer table of the proximal skull to the inner table of the distal skull. The head perimeter is the the total cranial circumference, which includes the maximum antero-posterior diameter. The occipitofrontal diameter is the front to back measurement from the outer table on both sides
56 Step by Step Ultrasound in Obstetrics 4.3 FETAL EVALUATION (MALFORMATIONS) The ideal way is to do a basic survey of fetal anatomy done systematically followed by a targeted fetal anatomy survey. 1. Cranium 2. Spine 3. Neck 4. Face 5. Thorax and heart 6. Abdomen 7. Extremities 4.4 CRANIUM (Figs 4.1 to 4.27) 1. Skull 2. Brain 3. Choroid Plexus a. Cysts b. Hydrocephalus 4. Posterior cranial fossa a. Cerebellar transverse diameter b. Depth of cisterna magna c. Superior and inferior cerebellar vermis d. Posterior fossa cyst e. Communication between fourth ventricle and cisterna magna 4.5 NUCHAL SKIN (Figs 4.28 to 4.33) 1. Thickness 2. Septations
Second Trimester 57
Fig. 4.2: Choroid plexus (CP) seen occupying the whole of the body of the lateral ventricle (LV). The anterior horn of the lateral ventricle (solid line) seen on the left side and posterior horn of the lateral ventricle (dashed line) seen on the right side are not filled by the choroid plexus.The choroid plexus quite often does not occupy the whole of the body of the lateral ventricle and the frontal and the posterior horn also are not filled by the choroids plexus. The width of the body of the lateral ventricle, the interhemispheric distance and the ratio of the width of the body of the lateral ventricle to the inter-hemispheric distance is calculated. (Normal value < 50%). This is not sensitive for early hydrocephalus. The width of the body, anterior horn and posterior horn of the lateral ventricle are taken. (Normal value < 08 mm, Borderline 08-10 mm and > 10 mm abnormal)
4.6 FETAL ORBITS AND FACE (Figs 4.34 to 4.48) 1. 2. 3. 4. 5.
Hypo and hypertelorism Lips Lens Nostrils Ear
58 Step by Step Ultrasound in Obstetrics
Fig. 4.3: When the choroid plexus does not occupy the whole of the body of the lateral ventricle see for the measurement of the medial separation (arrow) of the choroid plexus from the wall of the lateral ventricle. (Normal value < 02 mm, Borderline 02-03 mm and > 03 mm is abnormal)
Fig. 4.4: The cerebellum is seen as a ‘W’ turned 90 degrees. The cerebellar hemispheres (C) and the cerebellar vermis (within the circle) should be appreciated for posterior cranial fossa abnormalities
Second Trimester 59
Fig. 4.5: The cerebellar transverse diameter (CTD) is measured from the edges of both cerebellar hemispheres. The CTD in mm from 14-22 weeks is equal to the gestational age of the fetus in weeks
Fig. 4.6: The cisterna magna is seen posterior to the cerebellar vermis and anterior to the occipital bone (solid line). (Normal value < 08 mm, Borderline 08-10 mm and > 10 mm abnormal). Few strands seen traversing the cisterna magna are normal. Carefully check for any communication between the fourth ventricle and the cisterna magna with an abnormal cerebellar vermis. If there is any communication at gestational age less than 16 weeks revaluate the fetus after 2 weeks
60 Step by Step Ultrasound in Obstetrics
Fig. 4.7: Deformed cranium with almost no osseous area surrounding the floating brain (solid line)
Fig. 4.8: Fetal acrania. Note the brain tissue (solid line) but no osseous covering over it
Second Trimester 61
Fig. 4.9: Orbits (arrowheads) seen with nothing seen superior to it (neither brain nor bone)
Fig. 4.10: Anencephaly: Superior to the orbits no brain tissue or osseous portion is seen
62 Step by Step Ultrasound in Obstetrics
Fig. 4.11: Lateral occipital meningocele (solid line). Note the clear contents within the herniated sac
Fig. 4.12: Note the defect in the occipital bone (arrow) with the herniation of brain tissue from the defect
Second Trimester 63
Fig. 4.13: Iniencephaly (solid line) with a fixed retroflexion deformity of the fetal head
Fig. 4.14: Alobar holoprosencephaly with a dorsal sac (solid line) and a monoventricular cavity with a displaced cerebral cortex (dashed line)
64 Step by Step Ultrasound in Obstetrics
Fig. 4.15: Ventriculomegaly seen in the atrial and occipital regions (colpocephaly) because of poorly developed white matter surrounding these areas (Tear drop configuration) with an absent cavum septum pellucidum
Fig. 4.16: An enlarged elevated third ventricle is seen between the hemispheres which appears as an inter-hemispheric cyst
Second Trimester 65
Fig. 4.17: Large cyst in the posterior cranial fossa (star) with a hypoplastic cerebellar vermis (solid line)
Fig. 4.18: Midline cyst in the posterior cranial fossa which is communicating (solid line) with the fourth ventricle
66 Step by Step Ultrasound in Obstetrics
Fig. 4.19: Abnormally developed cerebellar vermis (solid line)
Fig. 4.20: Hydranencephaly with complete destruction of the cerebral cortex and basal ganglia with intact meninges and skull which is of normal appearance
Second Trimester 67
Fig. 4.21: Unilateral single (solid line) choroid plexus cyst
Fig. 4.22: Bilateral one on each side (solid line) choroid plexus cyst. A detailed scan to check for sonographic stigmata of chromosomal abnormalities especially Trisomy 18 is done and only if any additional anomaly is detected an amniocentesis is indicated for
68 Step by Step Ultrasound in Obstetrics
Fig. 4.23: Ventriculomegaly with hyperechoic walls and multiple foci of calcification seen in the brain substance
Fig. 4.24: Enlarged lateral ventricles with loss of the approximation between the choroid plexus and the medial border of the lateral ventricle (solid line)
Second Trimester 69
Fig. 4.25: Ventriculomegaly (left side) seen with a dysraphic disorganisation of the lumbar and sacrococcygeal vertebrae (solid line)
Fig. 4.26: Overlapping of the frontal bones (solid lines) seen in a case of communicating hydrocephalus
Fig. 4.27: Mass, possible a teratoma (solid lines) with dilatation of the lateral ventricles
70 Step by Step Ultrasound in Obstetrics
Fig. 4.28: Nuchal translucency in a 10 weeks fetus. Any thickening of the nuchal translucency prompts to a diagnosis of cystic hygroma, chromosomal abnormalities or cardiac abnormalities. Nuchal translucency in a 13 weeks fetus. Nuchal translucency thickness usually increases with gestational age with 1.5 mm and 2.5 mm being the 50th and 95th percentile respectively for gestational ages between 10 and 12 weeks. 2.0 mm and 3.0 mm are the 50th and 95th percentile respectively for gestational ages between 12 and 14 weeks
Fig. 4.29: Nuchal skin fold thickness assessment through the section for the cerebellum and cisterna magna
Second Trimester 71
Fig. 4.30: Nuchal skin fold thickness assessment through the section just inferior to the section for cerebellum and cisterna magna. (14-18 weeks : Normal value < 04 mm, Borderline 04-05 mm and > 05 mm requires further karyotypic analysis) (18-22 weeks : Normal value < 05 mm, Borderline 05-06 mm and > 06 mm requires further karyotypic analysis)
Fig. 4.31: Cystic hygroma seen in the longitudinal section across the entire fetal spine
72 Step by Step Ultrasound in Obstetrics
Fig. 4.32: Cystic hygroma seen in the longitudinal section posterior to the cranium, cranio-vertebral junction and cervical vertebra
Fig. 4.33: Cystic hygroma seen as a diffuse lesion along the fetal thorax and abdomen
Second Trimester 73
Fig. 4.34: Detailed facial anatomy which can be seen in a second trimester ultrasound. Note the eyelids, nose, lips, cheeks and chin which can be seen so clearly and can be shown to the expectant parents as well
Fig. 4.35: Saggital section through the mid-face showing the facial profile clearly
74 Step by Step Ultrasound in Obstetrics
Fig. 4.36: Fetal lens seen in both the orbits on ultrasound is seen as a hyperechoic rim with a sonolucent centre (solid lines)
Fig. 4.37: Fetal orbits (stars) should be carefully checked for their osseous continuity apart from the measurements.View for the measurements of ocular diameter (measured from medial inner to medial lateral wall of the long orbit), interoccular distance (measured from medial inner wall of one orbit to medial inner wall of the other orbit) and binocular distance (measured from lateral inner wall of one orbit to lateral inner wall of the other orbit)
Second Trimester 75
Fig. 4.38: Modified coronal view of the lower face showing the nostrils (solid lines) and the lips
Fig. 4.39: Sagittal view showing the forehead, maxilla and mandible (solid line)
76 Step by Step Ultrasound in Obstetrics
Fig. 4.40: Sagittal view of a normal fetal profile showing the osseous and soft tissue components. With the fetal mouth open the normal positioning of the tongue can also be seen (solid line)
Fig. 4.41: Parasaggital view showing the external ear
Second Trimester 77
Fig. 4.42: Unilateral cleft lip (solid line) extending into the maxilla as well
Fig. 4.43: Unilateral cleft lip (solid line). Note the dropout of echoes in the upper lip
78 Step by Step Ultrasound in Obstetrics 4.7 FETAL SPINE (Figs 4.49 to 4.60) 1. 2. 3. 4.
Coronal Longitudinal Axial Ossification Soft Tissues
4.8 FETAL THORAX (Figs 4.61 to 4.72) 1. 2. 3. 4. 5. 6.
Diaphragm Lung length Lung Echoes Ribs Masses Cardio-thoracic ratio
Fig. 4.44: Bilateral cleft lip and palate (solid line)
Second Trimester 79
Fig. 4.45: Amniotic bands (arrow) can be associated with a cleft lip or palate
Fig. 4.46: Fetal orbits seen in the coronal view to assess for hypo/hypertelorism
80 Step by Step Ultrasound in Obstetrics
Fig. 4.47: Hypotelorism seen in a case of semilobar holoprosencephaly. The ocular diamtere in this case was 12 mm, the interocular distance was 08 mm and the binocular distance was 32 mm
Fig. 4.48: Single nostril (solid line) seen in the case of hypotelorism with semilobar holoprosencephaly
Second Trimester 81
Fig. 4.49: Three ossification centres seen in the transverse plane. Two of these are posterior (solid line) and one is anterior (arrow head). Transverse planes to delineate any minimal widening of the inter-pedicular distance
Fig. 4.50: The cutaneous, subcutaneous and muscular components seen posterior to the vertebral column all along the cervical, dorsal, lumbar and sacrococcygeal vertebrae. The longitudinal plane of the fetal spine delineating the soft tissues posterior to the vertebral column and any dysraphic disorganisation of the spine
82 Step by Step Ultrasound in Obstetrics
Fig. 4.51: Sagittal plane to delineate the spinal cord in the lower cervical, dorsal and lumbar spine and to delineate any osseous deformity
Fig. 4.52: Defect in the osseous component of the vertebral column and disruption of cutaneous and subcutaneous elements. Osseous disorganisation of the fetal spine
Second Trimester 83
Fig. 4.53: Gross dysraphic disorganisation of the entire spine
Fig. 4.54: Bulging membrane covering the vertebral lesion (within circle)
84 Step by Step Ultrasound in Obstetrics
Fig. 4.55: Meningocele with anechoic contents (within circle)
Fig. 4.56: Lumbosacral meningomyelocele (within circle)
Second Trimester 85
Fig. 4.57: Diastematomyelic spur (solid line) with a spina bifida
Fig. 4.58: Gross dysraphic disorganisation of the entire fetal spine with a tethered spinal cord
86 Step by Step Ultrasound in Obstetrics
Fig. 4.59: Splitting of the spinal cord with a lumbosacral meningomyelocele
Fig. 4.60: Mass (star) seen inferior to the sacrococcygeal area (solid line). Sacrococcygeal mass with a solid cum cystic echo pattern
Second Trimester 87
Fig. 4.61: Longitudinal section through the fetal thorax on both sides to assess the fetal lungs
Fig. 4.62: Longitudinal section through the fetal thorax to assess the spine posteriorly (for osseous deformities, meningoceles or meningomyeloceles, anterior or posterior) and anterior thoracic wall anteriorly (for any thinning or ectopia cordis)
88 Step by Step Ultrasound in Obstetrics
Fig. 4.63: Diffusely homogeneous fetal lung (LU) seen as diffuse low level echoes in comparison with the fetal liver (L). Diaphragm seen as arrow heads
Fig. 4.64: Absent anterior thoracic wall with the fetal heart (solid line) seen outside the fetal thorax
Second Trimester 89
Fig. 4.65: Narrow fetal thorax (solid white line) in comparison with the fetal abdomen (dashed black line)
Fig. 4.66: Large pleural effusion (star) taking on the shape of the chest wall, diaphragm and mediastinal contour
90 Step by Step Ultrasound in Obstetrics
Fig. 4.67: Unilateral pleural effusion (star) taking the shape of the chest wall and mediastinum
Fig. 4.68: Bilateral pleural effusion (stars) with the lungs pushed posteriorly (L)
Second Trimester 91
Fig. 4.69: Bilateral pleural effusion (solid line) as a part of generalised hydrops. Note the cutaneous hydrops over the abdominal wall (arrowhead) and ascites (arrowhead)
Fig. 4.70: Cystic adenomatoid malformation of the right lung (solid line). Because of distal acoustic enhancement from very small cysts the lesion appears as a solid mass. Note the difference in echo pattern from the left lung (arrow head)
92 Step by Step Ultrasound in Obstetrics
Fig. 4.71: Fetal stomach (S) seen in the retrocardiac area with the diaphragm seen (arrowheads)
Fig. 4.72: Right sided diaphragmatic hernia. The mass (solid line) is almost isoechoic with the lung. The venous vascularity of this mass (arrowheads) is seen superior and inferior to the diaphragm and drains into the inferior vena cava inferiorly
Second Trimester 93
4.9 FETAL HEART (Figs 4.73 to 4.93) 1. 2. 3. 4. 5. 6. 7.
Situs Size Rate Rhythm Configuration Connections Fetal circulation
4.10 FETAL ABDOMEN (Figs 4.94 to 4.123) 1. Gastro-intestinal a. Stomach b. Duodenum c. Small Bowel d. Large Bowel e. Omentum f. Mesentery 2. Hepatobiliary a. Liver b. Gallbladder 3. Genitourinary a. Kidneys b. Ureters c. Urinary bladder 4. Pancreas 5. Spleen
94 Step by Step Ultrasound in Obstetrics
Fig. 4.73: Moderator band (solid line) seen in the right ventricle at the apex
Fig. 4.74: Aorto-septal continuity (arrowheads) seen in the long axis view. The left ventricle (LV), right ventricle (RV) and left atrium (LA) are also labelled
Second Trimester 95
Fig. 4.75: Aorto-septal continuity (arrowheads) seen in the long axis view
Fig. 4.76: Right ventricle (RV), pulmonary valve (arrowhead) and pulmonary artery (solid line) seen as the right ventricular outflow tract
96 Step by Step Ultrasound in Obstetrics
Fig. 4.77: Right ventricular outflow tract with the pulmonary artery (solid line) from the right ventricle going into the ductus arteriosus and descending aorta (arrowhead)
Fig. 4.78: Left ventricular outflow tract with aorto-septal continuity (left side) and right ventricular outflow tract with the pulmonary artery (right side) shown
Second Trimester 97
Fig. 4.79: Aortic arch seen from the fetal heart and its branches in the neck
Fig. 4.80: Right atrium (RA), right ventricle (RV) and pulmonary artery (arrowhead) seen in the short axis view encircling the aorta (solid line)
98 Step by Step Ultrasound in Obstetrics
Fig. 4.81: M-mode tracings to check for pericardial effusion, chamber size and wall thickness
Fig. 4.82: M-mode tracings with the cursor through the right ventricle, left ventricle and left atrium
Second Trimester 99
Fig. 4.83: Color flow mapping for assessing flow through and distal to the atrioventricular valves
Fig. 4.84: Color flow mapping for assessing flow through and distal to the semilunar valves
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Fig. 4.85: Doppler gate for sampling for arterial flow velocities across the atrioventricular valves for peak flow velocities and volume flow across these valves for delineation of stenosis or regurgitation
Fig. 4.86: Cardiomegaly with the cardio-thoracic ratio in this case as 80%
Second Trimester
101
Fig. 4.87: Four chamber view with a large ventricular septal defect (solid line) and an atrial septal defect (dashed line)
Fig. 4.88: Four chamber view with a perimembranous ventricular septal defect (arrow labelled)
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Fig. 4.89: Four chamber view with a large ventricular septal defect (solid line) and an atrial septal defect (dashed line)
Fig. 4.90: Cardiac rhabdomyoma (dashed line) with a diffuse thickening of the myocardium (solid lines)
Second Trimester
103
Fig. 4.91: Diffuse thickening of the myocardium with increased echogenecity in a case of cardiomyopathy
Fig. 4.92: Focal increase in echogenecity at the left atrio-ventricular junction with no myocardial thickening
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Fig. 4.93: Pericardial effusion (solid line) seen enveloping the fetal heart
Fig. 4.94: Pseudoascites (arrowheads) is the hypoechoic area seen only along the anterior and lateral aspects on the periphery commonly seen in a transverse section
Second Trimester
105
Fig. 4.95: Fluid filled structures, stomach (S) and urinary bladder (UB) seen in the fetal abdomen
Fig. 4.96: Normal colonic echoes (hypoechoic) seen at the periphery of the fetal abdomen (solid line)
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Fig. 4.97: Esophageal atresia as diagnosed by demonstration of polyhydramnios (right side) with an inability to visualise the stomach bubble (left side)
Fig. 4.98: Double bubble sign seen as a distended stomach (S) and an enlarged duodenal bulb (star)
Second Trimester
107
Fig. 4.99: Small bowel obstruction seen as multiple interconnecting, overdistended bowel loops more than 07 mm in diameter. Take care that you do not confuse the same picture with a multicystic dysplastic kidney or a dilated tortuous ureter
Fig. 4.100: Echogenic bowel (solid lines) which can be normally seen in a normal fetus at term with hyperechoic colonic meconium or hyperechoic bowel contents in the fetus who has swallowed intra-amniotic blood
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Fig. 4.101: Dilated large bowel segments (arrow) seen near the periphery in a case of anorectal malformation
Fig. 4.102: Dilated large bowel segments (stars) seen in a case of meconium plug syndrome
Second Trimester
109
Fig. 4.103: Scattered echogenic foci with distal acoustic shadowing in a case of meconium peritonitis
Fig. 4.104: Dense hyperechoic foci (arrows) seen in the periphery in a case of meconium peritonitis
Fig. 4.105: Meconium peritonitis with a meconium pseudocyst (solid line) with debris seen within it
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Fig. 4.106: Gastroschisis with bowel segments (solid line) seen floating freely in the amniotic fluid
Fig. 4.107: Anterior abdominal wall defect (gastroschisis) with the umbilical cord insertion on the side of the lesion (solid line) as seen on color flow mapping
Second Trimester
111
Fig. 4.108: Omphalocele with ascitic fluid and the umbilical cord (arrow) inserted on the tip of the lesion
Fig. 4.109: Omphalocele (solid line) seen in a case of trisomy 18
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Fig. 4.110: Multiple foci of hepatic calcification in a case of intrauterine infection
Fig. 4.111: Fetal hepatomegaly with calcification and ascites seen in a case of toxoplasmosis infection
Second Trimester
113
Fig. 4.112: Fetal splenomegaly (labelled) in a case of severe fetal hydrops
Fig. 4.113: Longitudinal scan of a normal kidney with its characteristic reniform shape
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Fig. 4.114: Transverse section through the fetal abdomen showing both kidneys (solid line) on either side of the spine (dashed line)
Fig. 4.115: Longitudinal scan of a normal kidney in the third trimester in a fetus of 33 weeks and 4 days. Note the central echogenic area (solid line) with hypoechoic pyramids (arrowheads)
Second Trimester
115
Fig. 4.116: Fetal adrenal glands as seen normally (solid lines). Be careful not to mistake the adrenal for a kidney especially in cases of renal agenesis. To differentiate remember that the adrenal gland does not have central sinus echoes and a reniform shape
Fig. 4.117: Obstruction of the urinary tract at the bladder outlet with an overdistended urinary bladder, dilated ureters on both sides and a bilateral hydronephrosis
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Fig. 4.118: Anteroposterior diameter of the renal pelvis (solid line). The values for the anteroposterior diameter of the renal pelvis (measured on a transverse view through the kidney) are from 15 to 20 weeks of gestation < 04 mm is normal, 04 to 07 mm is borderline and > 08 mm is abnormal or hydronephrotic. From 20 weeks onwards < 06 mm is normal, 06 to 09 is borderline and > 10 mm is abnormal or hydronephrotic. Be careful that borderline cases are to be reviewed by serial scans before labelling them as hydronephrotic
Fig. 4.119: Pelvi-ureteric junction obstruction with a dilated renal pelvis (solid line) with dilated calyces (arrowheads) No ureteric dilatation is seen
Second Trimester
117
Fig. 4.120: Bilateral echogenic kidneys which are dysplastic and small with very less pelviectasis. This is not a reduction in hydronephrosis as the improvement with dysplastic kidney is because the renal function is poor or absent and is not going to improve even after the obstruction is corrected
Fig. 4.121: Bladder outlet obstruction with dilatation of the proximal urethra (solid line) and a thickened urinary bladder wall (arrowhead)
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Fig. 4.122: Multicystic dysplastic kidney with multiple cysts and no normal renal parenchyma seen
Fig. 4.123: Bilateral multicystic dysplastic kidney with severe oligohydramnios
Second Trimester
119
4.11 FETAL SKELETON (Figs 4.124 to 4.135) 1. 2. 3. 4. 5.
Cranium Mandible Clavicle Spine Extremities
4.12 FETAL BIOMETRY 1. 2. 3. 4. 5. 6.
Bi-parietal diameter Occipito-frontal distance Head perimeter Abdominal perimeter Femoral length Humeral length
4.13 EXTRA-FETAL EVALUATION 1. Placenta (Location, Morphology, Focal lesions, Retroplacental area) (Figs 4.136 to 4.140) 2. Liquor amnii (Normal, Oligohydramnios, Polyhydramnios, Amniotic Bands) (Figs 4.141 to 4.144) 3. Umbilical cord (Number of Vessels, Origin and Insertion, Masses) (Figs 4.145 to 4.149) 4. Cervix (Internal os width, Length of cervix and Serial evaluation) (Figs 4.150 to 4.152) 5. Lower segment (Thickness) 6. Myometrium (Masses) (Fig. 4.153) 7. Adnexa (Masses) (Fig. 154)
120
Step by Step Ultrasound in Obstetrics
Fig. 4.124: Femoral length to be measured routinely in all obstetric ultrasound after 14 weeks. If a skeletal deformity is being suspected the tibial and fibular lengths also to be taken
Fig. 4.125: Fetal feet to be checked for their orientation with the tibia to make a diagnosis of club foot
Second Trimester
121
Fig. 4.126: Humeral length to be measured in all anomaly targeted obstetric ultrasound especially for chromosomal abnormalities after 14 weeks. If a skeletal deformity is being suspected the radial and ulnar lengths also to be taken
Fig. 4.127: Fetal hands to be checked for position, orientation and to look for poly/syndactyly
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Fig. 4.128: The fifth digit should be carefully assessed for any incurving or any hypoplasia of the middle phalanx of the fifth digit (solid line)
Fig. 4.129: Narrowing of the fetal thorax to be assessed by taking the thoracic perimeter and checking the abdominal perimeter/ thoracic perimeter ratio. One should also assess by taking the maximium antero-posterior measurement of the thorax and the abdomen on a longitudinal section. Configuration of ribs to be seen on both sides to check for any thoracic narrowing with resultant pulmonary hypoplasia and a bad prognosis
Second Trimester
123
Fig. 4.130: Report on parameters of a case of thanatophoric dysplasia. Cranial parameters and abdominal perimeter correspond to 19-20 weeks size, thoracic dimensions to 16 weeks size and bone lengths to 1415 weeks size
Fig. 4.131: Bowed long bones almost giving a telephone receiver appearance
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Fig. 4.132: Narrow thorax, in the longitudinal section compare the side to side measurement of the fetal thorax and abdomen
Fig. 4.133: Fetal foot turned medially in a case of club foot
Second Trimester
125
Fig. 4.134: Visualise the sole of the foot (within circle) and if in this view you can see the tibia (solid line) it is a club foot deformity
Fig. 4.135: Club foot deformity can be associated with Trisomy 18, so a thorough check for stigmata of Trisomy 18 should be done
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Fig. 4.136: An upper segment placenta as the placenta in this case is far away from the internal os
Fig. 4.137: The placenta is posterior. Its inferior limit extends down to the internal os but does not span across it
Second Trimester
127
Fig. 4.138: Grade I placenta at 20 weeks and 2 days
Fig. 4.139: Multiple anechoic or hypoechoic areas near the fetal surface or the uterine surface of the placenta are seen. The only focal lesion of significance is chorioangioma which is hypoechoic and very vascular
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Step by Step Ultrasound in Obstetrics
Fig. 4.140: The retroplacental area usually appears hypoechoic because of vessels, so do not mistake it as retroplacental collection
Fig. 4.141: Amniotic fluid index assessment. The uterus is divided into four quadrants by the midline and transverse axis and the amniotic fluid as the deepest vertical pocket free of fetal parts and umbilical cord is measured in each quadrant and all four quadrants add up to give the amniotic fluid index. Gradation of the amniotic fluid into oligo/polyhydramnios is then done
Second Trimester
129
Fig. 4.142: Severe oligohydramnios in a case of bilateral renal agenesis. Note the complete absence of liquor amnii with the uterine wall closely apposed to the fetus
Fig. 4.143: Moderate polyhydramnios in a case of congenital diaphragmatic hernia. Diagnosis is striking in these cases as the fetus is seen freely mobile in liquor amnii. Both pockets shown in the picture are more than 80 mm each
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Fig. 4.144: Amniotic fold/band seen traversing the uterine cavity. Be careful to check for any limb or digit reduction/ constriction defects, external anomalies of the face (cleft lip and palate, nasal abnormalities), cranum (anencephaly or encephalocele), anterior abdominal wall defects and abnormal curvature of the spine
Fig. 4.145: Three vessel cord as seen on 2D ultrasound. The single umbilical vein (solid line) and two umbilical arteries (dotted line) are seen as a rail track appearance
Second Trimester
131
Fig. 4.146: Three vessel cord as seen on color flow mapping. Two umbilical arteries (blue) and single umbilical vein (red) can be easily demonstrated. On color flow mapping the red and blue to not specify arteries and veins but flow towards the transducer or away from it
Fig. 4.147: Two vessel cord as seen on color flow mapping. Single umbilical artery (red) and single umbilical vein (blue) can be seen
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Fig. 4.148: Hypogastric arteries seen adjacent to the urinary bladder on both sides confirming a three vessel cord
Fig. 4.149: Hypogastric artery seen adjacent to the urinary bladder only on one side confirming a two vessel cord seen in Fig. 4.147
Second Trimester
133
Fig. 4.150: The internal os should be seen whether it is open or not and whether there is any herniation as well
Fig. 4.151: Length: The cervical length is measured from the internal os to the external os or the mucus plug is measured
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Fig. 4.152: Patient of cervical incompetence. The internal os (arrowheads) is open and 18 mm wide. The herniation of the amnion in the cervical canal (line) is over a distance of 32 mm. The functional or closed cervix (dashed line) which is required for the cerclage is 13 mm long
Fig. 4.153: An anterior wall subserous ibroid in a 16 weeks pregnancy
Second Trimester
Fig. 4.154: Persistent corpus luteum in a 19 weeks pregnancy
4.14 COLOR DOPPLER IN SECOND TRIMESTER 1. 2. 3. 4.
Uterine artery Umbilical artery Fetal circulation Placental perfusion
4.15 3D AND 4D SCAN 1. Surface anatomy
135
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2. Anomaly scan 3. Bone and spine evaluation 4. 4D scan for maternal-fetal and family-fetal bonding 4.16 ABNORMAL SECOND TRIMESTER 1. 2. 3. 4. 5. 6. 7.
Low placenta Separation Oligo/polyhydramnios Single umbilical artery Incompetent os Short cervix Malformations
4.17 DILEMMAS 1. Is it that with ultrasound one can find out each and every problem with the fetus, color Doppler is even better and is 3D the ultimate 2. Which period is best for diagnosing anomalies 3. Is the baby low 4. Will water drinking help for making of liquor 5. Ultrasound done at 13 weeks was normal, let’s skip this scan
Five
5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 5.10 5.11 5.12 5.13 5.14 5.15 5.16 5.17 5.18 5.19 5.20 5.21
Third Trimester Indications Fetal evaluation Extra-fetal evaluation Placental check list Amniotic fluid assessment Causes of oligohydramnios Causes of polyhydramnios Fetal growth Fetal surveillance or fetal wellbeing Biophysical profile Evaluation by biophysical profile Interpretation of biophysical profile Serial evaluation Color Doppler Indications for color Doppler Interpretation of the waveforms Indications of delivery Mode of delivery Abnormal third trimester Check list Dilemmas
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5.1 INDICATIONS 1. Suspected abruptio placentae 2. Estimation of fetal weight and /or presentation in premature rupture of membranes and /or premature labor 3. Serial evaluation of fetal growth in multiple gestations 4. Estimation of gestational age in late registrants for prenatal care 5. Biophysical profile for fetal well-being 6. Determination of fetal presentation 7. Suspected fetal death 8. Observation of intrapartum events 9. Suspected polyhydramnios or oligohydramnios 5.2 FETAL EVALUATION 1. Presentation: Cephalic/Breech(Extended or Footling)/ Oblique (Cranium in iliac fossae or hypochondrium (Figs 5.1 and 5.2). 2. Movements and biophysical score 3. Viability 4. Gestational age: Denotes fetal maturity (Fig. 5.3). 5. Biometry: Denotes fetal size and weight (Figs 5.4 to 5.6) 6. Color Doppler for fetal wellbeing 5.3 EXTRA-FETAL EVALUATION 1. Placenta: Grade I/II (with basal stippling)/III (with calcification) (Figs 5.7 and 5.8). 2. Liquor amnii: Normal/Oligohydramnios/Polyhydramnios (Figs 5.9 to 5.11).
Third Trimester 139
Fig. 5.1: Cephalic presentation with the cranium opposed to the cervix
Fig. 5.2: Extended breech presentation with the fetal buttocks opposed to the cervix
140
Step by Step Ultrasound in Obstetrics
Fig. 5.3: The distal femoral epiphysis can be measured and maturity known as it starts appearing only after 35 weeks
Fig. 5.4: Section for cranial biometry consisting of the thalamus, the third ventricle and the cavum septum pellucidum. The biparietal diameter is the side to side measurement from the outer table of the proximal skull to the inner table of the distal skull. The head perimeter is the total cranial circumference, which includes the maximum antero-posterior diameter. The occipitofrontal diameter is the front to back measurement from the outer table on both sides
Third Trimester 141
Fig. 5.5: Section for abdominal perimeter measurement. The spine should be posterior and the umbilical part of the portal vein anteriorly. Femoral length measurement for assessing fetal biometry
Fig. 5.6: The chart shows a fetal weight of 2328 grams for 34 weeks with an EDD of 30/08/03
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Fig. 5.7: Grade II placenta with basal stippling
Fig. 5.8: Grade III placenta with calcification along the basal plate, chorionic plate and intercotyledons
Third Trimester 143
Fig. 5.9: Amniotic fluid index assessment. The uterus is divided into four quadrants by the midline and transverse axis and the amniotic fluid as the deepest vertical pocket free of fetal parts and umbilical cord is measured in each quadrant and all four quadrants add up to give the amniotic fluid index. Pregnancy of 38 weeks and 5 days with normal liquor amnii
Fig. 5.10: Pregnancy of 37 weeks and 2 days with oligohydramnios
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Fig. 5.11: Remember that if you have a color Doppler switch on the color to measure the pocket of liquor because many a times there is only cord in that pocket and it will give a wrong amniotic fluid index. Pocket which is full of umbilical cord so this pocket measurement is 0 mm not 28 mm as originally thought on a 2D image
Fig. 5.12: Strong suspicion of two loops of umbilical cord on a 2D image
Third Trimester 145
3. Umbilical cord: Presenting/Around neck (Figs 5.12 to 5.14) 4. Cervix: Effaced/Uneffaced. 5. Lower segment: Thick (normorange)/Thinned (Fig. 5.15) 6. Myometrium 7. Adnexa 5.4 PLACENTAL CHECK LIST 1. Site of placentation 2. Relation of lower pole to internal os < 3cm placenta previa > 3 cm-5 low lying > 5 cm away normal placentation site 3. Grading for maturity (immature, mature or hypermature) only hypermature placenta before 34 weeks gestation is of significance 4. Check for hypoechoic since in between placenta and uterine wall (rules out placenta acreta) 5. Check for retroplacental clot, Abruptions, intraplacental haematomas, calcification 6. Color flow imaging (angio) for number of placental vessels and vasculature (to rule out placental insufficiency and infact). 5.5 AMNIOTIC FLUID ASSESSMENT Condition
Single pocket
AFI
Oligohydramnios Reduced Normal More than average Polyhydramnios
< 2 cm 2-3 cm 3-8 cm > 8-12 > 12
<7 7-10 10-17 17-25 > 25
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Fig. 5.13: Findings of 2D confirmed by color flow mapping when these two loops are demonstrated
Fig. 5.14: No cord seen near or around the fetal neck as seen on color flow mapping
Third Trimester 147
Fig. 5.15: Thinned lower segment scar seen in a patient of previous cesarian
Scan whole uterine cavity for single pocket measure largest vertical pool for AFI four quadrant method. 5.6 CAUSES OF OLIGOHYDRAMNIOS 1. Idiopathic 2. Decreased urine production because of bilateral renal disease (primarily renal/secondary renal dysfunction) 3. Post-compensatory sequelae of intrauterine growth retardation. 4. Rupture of membranes 5. Post-maturity 5.7 CAUSES OF POLYHYDRAMNIOS 1. Idiopathic 2. Open neural tube defects, e.g. Encephalocele, Meningomyelocele, Anencephaly.
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3. Abnormalities primarily due to gastro-intestinal obstruction, e.g. Esophageal atresia, duodenal atresia, small bowel atresia/ obstruction or secondarily due to compression of the gastro-intestinal system, e.g. Cystic adenomatoid malformation, mass in the mediastinum, diaphragmatic hernia commonly left side. 4. Maternal diabetes mellitus 5. Fetal hydrops (immune or non-immune) 6. Chromosomal abnormality: Trisomy 18. 5.8 FETAL GROWTH Fetal growth scan influenced by: 1. Small 2. Large 3. P.I.H. 4. A.P.H 5. Medical disorder in pregnancy 6. PROM 7. H/O previous small births IUGR/FGR Causes 1. Low growth potenlial (Intrinsic factors) a. Genetic predisposition b. Chromosomal anomaly c. Fetal infection d. Structural fetal defects e. Drugs and medications 2. Loss of growth support (Extrinsic factors) a. Unknown cause b. PIH
Third Trimester 149
c. d. e. f. g. h. i.
Diabetes Lupus Recurrent bleeding episodes Multiple pregnancy Malnutrition Drug abuse Uterine anomalies
Points to Remember 1. Abdominal circumference is most sensitive in 3rd trimester 2. Fetal weight estimation always carries an error of +/200 gm 3. Macrosomia is associated with polyhydramnios 4. Shoulder dystocia in labour cannot be predicted 5. Assymetrical and symmetrical growth restriction can occur together 5.9 FETAL SURVEILLANCE OR FETAL WELLBEING When to evaluate 1. Unexplained fetal death 2. Decreased fetal movements 3. Maternal chronic hypertension 4. Pre-eclampsia (P.I.H.) 5. Maternal diabetes mellitus 6. Chronic renal disease 7. Cyanotic heart disease 8. Rh or other isoimmunization 9. Haemoglobinopathies
150 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20.
Step by Step Ultrasound in Obstetrics
Immunological disorders Oligohydramnios Polyhydramnios Intrauterine growth retardation Multiple gestations Post-dated pregnancy Preterm labour Premature rupture of membranes History bleeding in first trimester Elderly women ART pregnancies
5.10 BIOPHYSICAL PROFILE (Fig. 5.16) 1. The fetal biophysical profile is a combination of acute and chronic markers.
Fig. 5.16: The non-stress test is seen by checking the heart rate before and after fetal movements, to see whether there is any increase for a sufficient period of time or not
Third Trimester 151
2. The fetal heart rate reactivity (NST), breathing movements, movements and tone are acute markers and are altered by acute hypoxic changes. 3. The chronic marker of fetal condition, amniotic fluid is an indicator of chronic fetal distress and is associated with reduction of fetal cardiac output away from non vital organs. 5.11 EVALUATION BY BIOPHYSICAL PROFILE 1. Fetal breathing–Movement is defined as 30 seconds of sustained breathing movement during a 30 minute observation period. 2. Fetal movement–Three or more gross body movements in a 30 minute observation period. 3. Fetal tone–One or more episodes of limb motion from a position of flexion to extension and a rapid return to flexion. 4. Fetal reactivity–Two or more FHR accelerations associated with fetal movement of at least 15 bpm and lasting at least 15 seconds in 20 minutes. 5. Fluid volume–Presence of a pocket of amniotic fluid that measures at least 1 cm in two perpendicular planes. 5.12 INTERPRETATION OF BIOPHYSICAL PROFILE Manning score—Each variable is allotted a score of 0-2. 1. A score of > 8 is normal. 2. A score of 6-8 is suboptimal 3. A score of < 6 needs intervention
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The Manning’s biophysical profile scoring is a time consuming test (at least 40 minutes). Also it takes into account four acute variables and one chronic variable. Sometimes the acute variables are affected late and remain normal (Score 08/10) while the fetus may be having severe chronic distress (AFI < 5).This makes the Manning score unpredictable. To avoid this confusion a modified score has been proposed by Vintzelo’s which takes only two variables into account. 1. Liquor amnii: 2. Fetal NST in response to acoustic stimulation (VAST) This not only shortens the test duration (less than 20 mins) but also makes interpretation easy and more accurate. Interpretation 1. 2. 3. 4. 5.
AFI < 5. Distress delivery if viable (>28 weeks) If both normal wait for one week If NST normal but liquor less: Detailed color Doppler If liquor normal but NST abnormal: Acute distress If both abnormal: Individualise treatment according to gestational age.
5.13 SERIAL EVALUATION 1. It is recommended that an NST be performed twice a week on all postdated, diabetic, and IUGR patients. 2. Patient management is often dictated by the amount of amniotic fluid (postdate and IUGR patients). The detection of fetal anomalies combined with the ability to evaluate the amount of amniotic fluid are frequently stated as advantages of the biophysical profile over additional FHR testing in the form of OCT/CST.
Third Trimester 153
5.14 COLOR DOPPLER These are done to detect and assess the fetus at risk for death or damage in utero. Color Doppler in conjunction with 2D ultrasound and biophysical scoring is now regarded as an indispensable component of a pregnancy sonogram. 5.15 INDICATIONS FOR COLOR DOPPLER 1. Assessment and continued monitoring of the small for gestational age fetus. 2. Assessment of the fetus of a mother with systemic lupus erythematous (SLE) and PET. 3. Assessment of differing sizes or growth patterns in twins. 4. Conjunction with uteroplacental waveforms in the assessment of oligohydramnios. 5.16 INTERPRETATION OF THE WAVEFORMS (Figs 5.17 to 5.30) 1. In the absence of an acute incident such as a placental abruption, a small for gestational age fetus with normal umbilical artery waveforms will not develop loss of end-diastolic frequencies within a 7 day period, so that monitoring may be performed weekly. 2. Only 10% of fetuses that are demonstrated to be asymmetrically small for gestational age on realtime ultrasound will demonstrate loss of enddiastolic frequencies at any time during their pregnancy. 3. Loss of end-diastolic frequencies is associated with an 85% chance that the fetus will be hypoxic in utero and a 50% chance that it will also be acidotic.
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Step by Step Ultrasound in Obstetrics
Fig. 5.17: Uterine arteries reflect trophoblastic invasion and the prediction of a hypertensive disorder in low-risk mothers and perinatal morbidity and mortality in highrisk mothers. Normal uterine artery flow with flow in diastole and a Resistive Index of less than 0.55 after 22 weeks
Fig. 5.18: Abnormal waveform showing a notch in early diastole. Other abnormal waveforms can have a systolic notch or a Resistive Index of more than 0.55 or a major right to left variation
Third Trimester 155
Fig. 5.19: Umbilical arteries reflect placental obliteration and one should have sufficient flow in diastole for a normal waveform
Fig. 5.20: Abnormal waveform has absent end diastolic flow or reversal of end diastolic flow. This waveform shows reversal of flow in diastole
156
Step by Step Ultrasound in Obstetrics
Fig. 5.21: Normal continuous flow in a umbilical vein flow pattern and this reflects myocardial function
Fig. 5.22: Double pulsatile pattern seen in an abnormal umbilical vein flow pattern
Third Trimester 157
Fig. 5.23: The middle cerebral artery waveform reflects altered cerebral flow or cerebral edema. In hypoxia the blood flow to the middle cerebral artery increases as a reflex redistribution of fetal cardiac output. Normal waveform with a Pulsatility Index of 2.15
Fig. 5.24: Abnormal waveform with increased blood flow to the middle cerebral artery with a PI of 0.76
158
Step by Step Ultrasound in Obstetrics
Fig. 5.25: Descending aorta reflects flow from the abdominal viscera and lower limbs. Normal waveform with adequate diastolic flow
Fig. 5.26: Abnormal waveform with reduced flow in diastole for redistribution to other vital organs
Third Trimester 159
Fig. 5.27: Ductus venosus flow reflects acidosis. Normal waveform with plenty of flow in diastole
Fig. 5.28: Abnormal waveform with a reduced forward flow in diastole
160
Step by Step Ultrasound in Obstetrics
Fig. 5.29: Normal triphasic inferior vena cava flow reflecting myocardial function
Fig. 5.30: Abnormal waveform with an increased reversed flow in diastole
Third Trimester 161
4. The finding of a symmetrically small fetus with absent end-diastolic frequencies in the umbilical artery but with normal utero-placental waveforms suggest the possibility of a primary fetal cause for the growth retardation such as chromosomal abnormality or a TORCH virus infection. 5. Fetuses demonstrating absence of end-diastolic frequencies but which are managed along standard clinical lines have a 40% chance of dying and at least a 25% morbidity rate from necrotizing enterocolitis, hemorrhage or coagulation fracture after birth. The time between loss of end-diastolic frequencies and fetal death appears to differ for each fetus, Following loss of end-diastolic frequencies there are no other reliable changes in the waveform that help in deciding when to deliver the baby. 6. Reversed frequencies in end-diastolic are only observed in a few fetuses prior to death. This finding is a pre-terminal condition; few if any, fetuses will service without some form of therapeutic intervention. 7. Loss of end-diastolic frequencies precedes changes in the cardiotocograph by some 7-42 days in fetuses that have been shown to be small for gestational age on real-time ultrasound. The occurrence of CTG decelerations not related to contractions, together with absent end-diastolic frequencies, carries an extremely poor prognosis. 8. In case of IUGR Wladimiroff and colleagues (1986) have described compensatory reduction in vascular
162
9.
10.
11.
12.
Step by Step Ultrasound in Obstetrics
resistance in fetal brain during fetal hypoxemia usually called as ‘Brain sparing effect’ and is the earliest Doppler based marker for IUGR compromised fetus. Detection of elevated resistance to flow within fetal descending aorta reflects the decreased vascular resistance associated with high-risk pregnancy not only within the placental vascular bed but also within fetal abdominal viscera. Increased resistance in fetal renal arteries with growth retardation has been seen especially with oligohydramnios. Increased resistance in uterine artery as indicated by an elevated index of resistance by persistence of an early diastolic notch often precedes the onset of growth retardation. The details of normal and abnormal waveforms with their representations and end points and management protocols is discussed in detail in the STEP BY STEP series on Ultrasound and Color Doppler.
5.17 INDICATIONS OF DELIVERY • • • •
Viable fetus AFI < 5 Absent end-diastolic flow or reversed end-diastolic flow in umbilical artery after 35 weeks Abnormal ductus venosus flow > 35 weeks Abnormal biophysical profile
5.18 MODE OF DELIVERY Vaginal or cesarian section depends on cervical score, pelvis and/or any other obstetric indication for cesarian section.
Third Trimester 163
5.19 ABNORMAL THIRD TRIMESTER 1. 2. 3. 4. 5. 6. 7. 8. 9.
Placental aging Separation Oligo/polyhydramnios Cord around neck Thinned lower segment Abnormal presentation IUGR Abnormal biophysical score Abnormal color Doppler studies
5.20 CHECK LIST 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.
Calculate gestation from L.M.P.(keep card with you) Fundal height clinical size Presentation and lie BPD HC AC FL Other limbs High circumference Charts and assess growth
5.21 DILEMMAS 1. 2. 3. 4. 5. 6. 7. 8.
Will the ultrasound tell us the exact date of delivery All parameters give different EDD Has the internal os opened There is a cord around the neck: is it dangerous Has the baby come in the final position How many movements are normal First ultrasound: please check for anomalies Can we wait more
Index A Abnormal fetus 48 Abnormal second trimester 136 Abnormal third trimester 163 Amniotic fluid assessment 145
B Biophysical profile 150
C Classification of early pregnancy loss 24 Color Doppler indications for 153 interpretation of waveforms 153 Color Doppler in second trimester 135 Cranium 56
D
Fetal heart 93 Fetal orbits and face 57 Fetal skeleton 119 Fetal spine 78 Fetal thorax 78 Fetal wellbeing 149 First trimester embryonic/fetal evaluation 15 abnormal intrauterine pregnancy 23 complete abortion 33 incomplete abortion 33 molar change 39 extra fetal evaluation 33 impending early pregnancy failure 23 normal parameter 23
I Indications of delivery 162 IUGR/FGR 148
3D and 4D scan 135
M
E
Machine 3 Malformations 56 Molar change 39
Ectopic gestation 28 Extra-fetal evaluation 33, 119, 138
F Fetal abdomen 93 Fetal biometry 119 Fetal evaluation 55, 138 Fetal growth 148
N Nuchal skin 56
O Oligohydramnios 147
166
Step by Step Ultrasound in Obstetrics
P
R
Placental check list 145 Polyhydramnios 147 Practice of ultrasound 8 mandatory proposed certification 12 prerequisite criteria 11 theoretical aspects 8 training parameters 9 training schedule 10
Relevant history 1 Reporting 4
S Sono-embryology chart 41
T Transducers 3 Transvaginal decision 52
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FPD BANKING DETAILS:
EMAIL, POST OR FAX YOUR REGISTRATION FORM TOGETHER WITH YOUR PAYMENT TO:
Nedbank Branch - Commercial, Pretoria Account number: 1497 046 238 · Branch code: 14 97 45
DANIELLE DANIELS ·
PLEASE REMEMBER TO INDICATE THE PAYMENT REFERENCE AS BELOW AND FAX US THE DEPOSIT SLIP!
Email: [email protected] Tel: 012 816 9000 · Fax: 012 807 7165 · Postal address: PO Box 75324, Lynnwood Ridge, 0040 Cheques must be made out to the Foundation for Professional Development
CANCELLATIONS:
PAYMENT OF FEES:
FPD reserves the right to cancel or postpone a course. Applicants will be informed and all fees will be refunded. Cancellations are accepted, IN WRITING and WITHOUT PENALTY, up to 14 days prior to date of commencement. Students cancelling less than 14 DAYS prior to date of commencement of the course will be liable for payment of 50% of the fees. NON-ARRIVALS will be liable for payment of the full fees. SUBSTITUTES will be accepted.
Students are responsible for paying t he full course fee before commencement thereof, or a s per available payment options on a per course basis.
PAYMENT REFERENCE
Pretoria - 2501/SURNAME
Kwa-Zulu Natal - 2502/SURNAME
Cape Town - 2503/SURNAME
Port Elizabeth - 2504/SURNAME
SUBSCRIPTION
As registered student you will be included in our alumni mailing list for updates and/or information on new courses. Should you wish to subscribe, please sign. Signature:
Date: