Ebook Diagnostic imaging obstetrics (2nd edition): Part 1

Diagnostic Imaging Obstetrics,
2nd Edition


Diagnostic Imaging Obstetrics, 2nd Edition

Table of Contents
Diagnostic Imaging Obstetrics, 2nd Edition .................................................................................................. 8
Cover ....................................................................................................................................................... 8
Authors.................................................................................................................................................... 8
Dedication ..............................................................................................................................................10
Preface ...................................................................................................................................................10
Acknowledgements ................................................................................................................................11
Section 1 - First Trimester .......................................................................................................................12
I. Introduction and Overview...............................................................................................................12
1. Embryology and Anatomy of the First Trimester ..........................................................................12
2. Approach to the First Trimester ...................................................................................................27
II. Intrauterine Gestation.....................................................................................................................32
3. Failed First Trimester Pregnancy ..................................................................................................32
4. Perigestational Hemorrhage ........................................................................................................39
5. Chorionic Bump...........................................................................................................................45
III. Ectopic Gestation ...........................................................................................................................48
6. Tubal Ectopic ...............................................................................................................................48
7. Interstitial Ectopic .......................................................................................................................58
8. Cervical Ectopic ...........................................................................................................................64
9. C-Section Scar Ectopic .................................................................................................................71
10. Abdominal Ectopic.....................................................................................................................74
11. Heterotopic Pregnancy ..............................................................................................................77
Section 2 - Brain......................................................................................................................................80
I. Introduction and Overview...............................................................................................................80
12. Embryology and Anatomy of the Brain ......................................................................................80

13. Approach to the Supratentorial Brain ........................................................................................99
14. Approach to the Posterior Fossa ..............................................................................................107
II. Cranial Defects ..............................................................................................................................116
15. Exencephaly, Anencephaly ......................................................................................................116
16. Acalvaria, Acrania ....................................................................................................................122
17. Occipital, Parietal Cephalocele ................................................................................................128
18. Frontal Cephalocele.................................................................................................................137
III. Midline Developmental Anomalies ...............................................................................................141
19. Agenesis of the Corpus Callosum .............................................................................................141
20. Atelencephaly, Aprosencephaly...............................................................................................147
21. Alobar Holoprosencephaly ......................................................................................................153
22. Semilobar Holoprosencephaly .................................................................................................160
23. Lobar Holoprosencephaly ........................................................................................................166
24. Septo-Optic Dysplasia ..............................................................................................................172
25. Syntelencephaly ......................................................................................................................178
IV. Cortical Developmental Anomalies...............................................................................................184
26. Schizencephaly ........................................................................................................................184
27. Lissencephaly ..........................................................................................................................191
28. Gray Matter Heterotopia .........................................................................................................197
29. Pachygyria, Polymicrogyria ......................................................................................................200
V. Cysts .............................................................................................................................................206
30. Choroid Plexus Cyst .................................................................................................................206
31. Arachnoid Cyst ........................................................................................................................213
32. Glioependymal Cyst.................................................................................................................219
VI. Destructive Lesions ......................................................................................................................226
33. Intracranial Hemorrhage .........................................................................................................226
34. Encephalomalacia, Porencephaly ............................................................................................232
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Diagnostic Imaging Obstetrics, 2nd Edition
35. Hydranencephaly ....................................................................................................................239
VII. Posterior Fossa Malformations....................................................................................................245
36. Aqueductal Stenosis ................................................................................................................245
37. Chiari 2 ....................................................................................................................................252
38. Chiari 3 ....................................................................................................................................259
39. Dandy-Walker Malformation ...................................................................................................262
40. Vermian Agenesis - Partial Or Complete ..................................................................................268
41. Blake Pouch Cyst .....................................................................................................................272
42. Mega Cisterna Magna..............................................................................................................278
43. Cerebellar Hypoplasia..............................................................................................................281
44. Rhombencephalosynapsis .......................................................................................................287
VIII. Vascular Malformations .............................................................................................................290
45. Vein of Galen Malformation ....................................................................................................290
46. Arteriovenous Fistula ..............................................................................................................296
47. Dural Sinus Malformation ........................................................................................................300
IX. Tumors.........................................................................................................................................303
48. Parenchymal Brain Tumors ......................................................................................................303
49. Choroid Plexus Papilloma ........................................................................................................309
50. Lipoma ....................................................................................................................................313
Section 3 - Spine ...................................................................................................................................316
51. Embryology and Anatomy of the Spine ........................................................................................316
52. Approach to the Fetal Spine ........................................................................................................327
53. Spina Bifida .................................................................................................................................329
54. Iniencephaly................................................................................................................................336
55. Caudal Regression Sequence .......................................................................................................343
56. Kyphosis, Scoliosis .......................................................................................................................350
57. Tethered Cord .............................................................................................................................357
58. Diastematomyelia .......................................................................................................................360
59. Sacrococcygeal Teratoma ............................................................................................................363

Section 4 - Face and Neck .....................................................................................................................369
60. Embryology and Anatomy of the Face and Neck ..........................................................................369
61. Approach to the Fetal Face and Neck ..........................................................................................383
62. Cleft Lip, Palate ...........................................................................................................................389
63. Absent Nasal Bone ......................................................................................................................399
64. Dacrocystocele ............................................................................................................................406
65. Coloboma....................................................................................................................................409
66. Epignathus ..................................................................................................................................412
67. Goiter..........................................................................................................................................418
68. Cystic Hygroma ...........................................................................................................................425
69. Cervical Teratoma .......................................................................................................................432
Section 5 - Chest ...................................................................................................................................438
70. Embryology and Anatomy of the Chest........................................................................................438
71. Approach to the Fetal Chest ........................................................................................................449
72. Congenital Diaphragmatic Hernia ................................................................................................452
73. Congenital Pulmonary Airway Malformation ...............................................................................459
74. Pleural Effusion ...........................................................................................................................465
75. Bronchopulmonary Sequestration ...............................................................................................472
76. Bronchogenic Cyst .......................................................................................................................479
77. Congenital High Airway Obstruction Sequence ............................................................................482
78. Pulmonary Agenesis ....................................................................................................................485
79. Lymphangioma............................................................................................................................488
80. Mediastinal, Pulmonary Teratoma...............................................................................................495
Section 6 - Heart ...................................................................................................................................498
I. Introduction and Overview.............................................................................................................498
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Diagnostic Imaging Obstetrics, 2nd Edition
81. Embryology and Anatomy of the Cardiovascular System..........................................................498

82. Approach to the Fetal Heart ....................................................................................................515
II. Abnormal Location ........................................................................................................................524
83. Situs Inversus ..........................................................................................................................524
84. Heterotaxy, Cardiosplenic Syndromes .....................................................................................527
85. Ectopia Cordis .........................................................................................................................533
III. Septal Defects ..............................................................................................................................540
86. Ventricular Septal Defect .........................................................................................................540
87. Atrioventricular Septal Defect .................................................................................................543
88. Foramen Ovale Aneurysm .......................................................................................................549
IV. Right Heart Malformations...........................................................................................................553
89. Ebstein Anomaly......................................................................................................................553
90. Tricuspid Dysplasia ..................................................................................................................556
91. Tricuspid Atresia......................................................................................................................559
92. Pulmonary Stenosis, Atresia ....................................................................................................562
V. Left Heart Malformations ..............................................................................................................568
93. Hypoplastic Left Heart .............................................................................................................568
94. Coarctation and Interrupted Aortic Arch ..................................................................................575
95. Aortic Stenosis.........................................................................................................................581
96. Double Inlet Left Ventricle .......................................................................................................588
VI. Conotruncal Malformations .........................................................................................................591
97. Tetralogy of Fallot ...................................................................................................................591
98. Transposition of the Great Arteries..........................................................................................598
99. Truncus Arteriosus ..................................................................................................................604
100. Double Outlet Right Ventricle ................................................................................................611
VII. Myocardial and Pericardial Abnormalities ...................................................................................614
101. Echogenic Cardiac Focus ........................................................................................................614
102. Hypertrophic Cardiomyopathy...............................................................................................618
103. Dilated Cardiomyopathy ........................................................................................................624
104. Rhabdomyoma ......................................................................................................................631
105. Pericardial Effusion................................................................................................................637

106. Pericardial Teratoma .............................................................................................................641
VIII. Abnormal Rhythm ......................................................................................................................644
107. Irregular Rhythm ...................................................................................................................644
108. Tachyarrhythmia ...................................................................................................................647
109. Bradyarrhythmia ...................................................................................................................653
Section 7 - Abdominal Wall and Gastrointestinal Tract ..........................................................................660
I. Introduction and Overview.............................................................................................................660
110. Embryology and Anatomy of the Abdominal Wall and GI Tract ..............................................660
111. Approach to the Abdominal Wall and Gi Tract .......................................................................674
II. Abdominal Wall Defects ................................................................................................................682
112. Gastroschisis .........................................................................................................................682
113. Omphalocele .........................................................................................................................688
114. Pentalogy of Cantrell .............................................................................................................695
115. Body Stalk Anomaly ...............................................................................................................698
116. Bladder Exstrophy .................................................................................................................705
117. Cloacal Exstrophy - OEIS Syndrome........................................................................................708
III. Bowel Abnormalities ....................................................................................................................714
118. Esophageal Atresia ................................................................................................................714
119. Duodenal Atresia ...................................................................................................................720
120. Jejunal Ileal Atresia................................................................................................................727
121. Anal Atresia ...........................................................................................................................733
122. Cloacal Malformation ............................................................................................................739
123. Volvulus ................................................................................................................................746
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Diagnostic Imaging Obstetrics, 2nd Edition
124. Enteric Duplication Cyst .........................................................................................................749
IV. Peritoneal Abnormalities .............................................................................................................752
125. Ascites ...................................................................................................................................752

126. Meconium Peritonitis, Pseudocyst .........................................................................................759
127. Mesenteric Cyst.....................................................................................................................765
V. Hepatobiliary Abnormalities..........................................................................................................769
128. Gallstones .............................................................................................................................769
129. Choledochal Cyst ...................................................................................................................772
130. Infantile Hemangioendothelioma ..........................................................................................775
131. Mesenchymal Hamartoma ....................................................................................................781
132. Malignant Liver Tumors .........................................................................................................785
Section 8 - Genitourinary Tract .............................................................................................................791
I. Introduction and Overview.............................................................................................................791
133. Embryology and Anatomy of the Genitourinary Tract ............................................................791
134. Approach to the Fetal Genitourinary Tract .............................................................................808
II. Renal Developmental Variants ......................................................................................................813
135. Unilateral Renal Agenesis ......................................................................................................813
136. Duplicated Collecting System.................................................................................................817
137. Pelvic Kidney .........................................................................................................................823
138. Horseshoe Kidney ..................................................................................................................826
139. Crossed Fused Ectopia ...........................................................................................................829
III. Renal Malformations ....................................................................................................................833
140. Bilateral Renal Agenesis.........................................................................................................833
141. Mild Pelviectasis ....................................................................................................................839
142. Ureteropelvic Junction Obstruction .......................................................................................846
143. Urinoma ................................................................................................................................853
144. Obstructive Renal Dysplasia...................................................................................................856
145. Multicystic Dysplastic Kidney .................................................................................................863
146. Autosomal Recessive Polycystic Kidney Disease .....................................................................870
147. Mesoblastic Nephroma .........................................................................................................876
IV. Adrenal Abnormalities .................................................................................................................882
148. Adrenal Hemorrhage .............................................................................................................882
149. Neuroblastoma .....................................................................................................................886

V. Bladder Malformations .................................................................................................................892
150. Posterior Urethral Valves.......................................................................................................892
151. Prune Belly Syndrome ...........................................................................................................898
152. Ureterocele ...........................................................................................................................905
153. Urachal Anomalies.................................................................................................................911
VI. Genital Abnormalities ..................................................................................................................917
154. Ambiguous Genitalia .............................................................................................................917
155. Hypospadias ..........................................................................................................................928
156. Hydrocele ..............................................................................................................................931
157. Testicular Torsion ..................................................................................................................934
158. Inguinal Hernia ......................................................................................................................938
159. Ovarian Cyst ..........................................................................................................................941
160. Hydrocolpos ..........................................................................................................................947
Section 9 - Musculoskeletal...................................................................................................................951
I. Dysplasias ......................................................................................................................................951
161. Approach to Skeletal Dysplasias.............................................................................................951
162. Achondrogenesis, Hypochondrogenesis ................................................................................962
163. Achondroplasia .....................................................................................................................971
164. Amelia, Micromelia ...............................................................................................................978
165. Asphyxiating Thoracic Dysplasia ............................................................................................984
166. Atelosteogenesis ...................................................................................................................990
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Diagnostic Imaging Obstetrics, 2nd Edition
167. Campomelic Dysplasia ...........................................................................................................993
168. Chondrodysplasia Punctata ...................................................................................................999
169. Hypophosphatasia ............................................................................................................... 1005
170. Osteogenesis Imperfecta ..................................................................................................... 1008
171. Short Rib-Polydactyly Syndrome .......................................................................................... 1015

172. Thanatophoric Dysplasia...................................................................................................... 1018
II. Extremity Malformations ............................................................................................................ 1027
173. Clubfoot .............................................................................................................................. 1027
174. Rockerbottom Foot ............................................................................................................. 1034
175. Sandal Gap Foot .................................................................................................................. 1037
176. Radial Ray Malformation ..................................................................................................... 1040
177. Clinodactyly ......................................................................................................................... 1047
178. Polydactyly .......................................................................................................................... 1050
179. Syndactyly ........................................................................................................................... 1057
180. Split Hand - Foot Malformation ........................................................................................... 1063
181. Arthrogryposis, Akinesia Sequence ...................................................................................... 1070
182. Proximal Focal Femoral Dysplasia ........................................................................................ 1079
Section 10 - Placenta, Membranes, and Umbilical Cord ....................................................................... 1086
I. Introduction and Overview........................................................................................................... 1086
183. Approach to the Placenta and Umbilical Cord ...................................................................... 1086
II. Placenta and Membrane Abnormalities....................................................................................... 1095
184. Placental Abruption ............................................................................................................. 1095
185. Placenta Previa .................................................................................................................... 1102
186. Vasa Previa .......................................................................................................................... 1109
187. Placenta Accreta Spectrum .................................................................................................. 1112
188. Placental Lake, Intervillous Thrombus .................................................................................. 1119
189. Succenturiate Lobe .............................................................................................................. 1126
190. Circumvallate Placenta ........................................................................................................ 1129
191. Marginal Cord Insertion ....................................................................................................... 1133
192. Velamentous Cord Insertion ................................................................................................ 1136
193. Chorioangioma .................................................................................................................... 1140
194. Placental Teratoma ............................................................................................................. 1146
195. Chorioamniotic Separation .................................................................................................. 1150
III. Umbilical Cord Abnormalities ..................................................................................................... 1153
196. Single Umbilical Artery ........................................................................................................ 1153

197. Umbilical Cord Cyst ............................................................................................................. 1161
198. Umbilical Vein Varix............................................................................................................. 1168
199. Umbilical Artery Aneurysm .................................................................................................. 1174
200. Persistent Right Umbilical Vein ............................................................................................ 1178
201. Umbilical Vessel Thrombosis ............................................................................................... 1181
Section 11 - Multiple Gestations ......................................................................................................... 1185
202. Approach to Multiple Gestations ............................................................................................. 1185
203. Dichorionic Diamniotic Twins .................................................................................................. 1190
204. Monochorionic Diamniotic Twins ............................................................................................ 1196
205. Monochorionic Monoamniotic Twins ...................................................................................... 1203
206. Discordant Twin Growth .......................................................................................................... 1209
207. Twin-Twin Transfusion Syndrome ............................................................................................ 1215
208. Twin Reversed Arterial Perfusion............................................................................................. 1221
209. Conjoined Twins ...................................................................................................................... 1227
210. Triplets and Beyond ................................................................................................................ 1233
211. Fetus-in-Fetu ........................................................................................................................... 1239
Section 12 - Aneuploidy ...................................................................................................................... 1245
212. Screening for Aneuploidy ........................................................................................................ 1245
213. Trisomy 21 .............................................................................................................................. 1251
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Diagnostic Imaging Obstetrics, 2nd Edition
214. Trisomy 18 .............................................................................................................................. 1261
215. Trisomy 13 .............................................................................................................................. 1271
216. Turner Syndrome .................................................................................................................... 1281
217. Triploidy .................................................................................................................................. 1288
Section 13 - Syndromes and Multisystem Disorders ............................................................................ 1295
218. 22Q11 Deletion Syndrome ...................................................................................................... 1295
219. Aicardi Syndrome .................................................................................................................... 1298

220. Amniotic Band Syndrome ........................................................................................................ 1304
221. Apert Syndrome ...................................................................................................................... 1311
222. Beckwith-Wiedemann Syndrome ............................................................................................ 1317
223. Carpenter Syndrome ............................................................................................................... 1323
224. CHARGE Syndrome .................................................................................................................. 1326
225. Cornelia De Lange Syndrome ................................................................................................... 1329
226. Cystic Fibrosis .......................................................................................................................... 1333
227. Diabetic Embryopathy ............................................................................................................. 1336
228. Fryns Syndrome ...................................................................................................................... 1342
229. Holt-Oram Syndrome .............................................................................................................. 1345
230. Joubert Syndrome ................................................................................................................... 1351
231. Meckel-Gruber Syndrome ....................................................................................................... 1354
232. Multiple Pterygium Syndromes ............................................................................................... 1360
233. Neu-Laxova Syndrome............................................................................................................. 1364
234. PHACES Syndrome................................................................................................................... 1367
235. Pfeiffer Syndrome ................................................................................................................... 1370
236. Pierre Robin Anomaly .............................................................................................................. 1376
237. Sirenomelia ............................................................................................................................. 1379
238. Smith-Lemli-Opitz Syndrome ................................................................................................... 1385
239. Tuberous Sclerosis................................................................................................................... 1392
240. VACTERL Association ............................................................................................................... 1398
241. Valproate Embryopathy .......................................................................................................... 1405
242. Warfarin Embryopathy ............................................................................................................ 1408
243. Walker-Warburg Syndrome ..................................................................................................... 1411
Section 14 - Infection .......................................................................................................................... 1414
244. Cytomegalovirus ..................................................................................................................... 1414
245. Parvovirus ............................................................................................................................... 1420
246. Toxoplasmosis ......................................................................................................................... 1424
247. Varicella .................................................................................................................................. 1426
Section 15 - Fluid, Growth, and Well-Being ......................................................................................... 1430

248. Approach to Fetal Well-Being .................................................................................................. 1430
249. Polyhydramnios ...................................................................................................................... 1438
250. Oligohydramnios ..................................................................................................................... 1445
251. Intrauterine Growth Restriction .............................................................................................. 1452
252. Macrosomia ............................................................................................................................ 1459
253. Hydrops .................................................................................................................................. 1462
254. Fetal Anemia ........................................................................................................................... 1469
Section 16 - Maternal Conditions in Pregnancy ................................................................................... 1476
I. Gestational Trophoblastic Disease ................................................................................................ 1476
255. Complete Hydatidiform Mole .............................................................................................. 1476
256. Invasive Mole ...................................................................................................................... 1483
257. Choriocarcinoma ................................................................................................................. 1486
II. Uterus ......................................................................................................................................... 1492
258. Incompetent Cervix ............................................................................................................. 1492
259. Myoma in Pregnancy ........................................................................................................... 1499
260. MüLlerian Duct Anomalies in Pregnancy .............................................................................. 1506
261. Synechiae ............................................................................................................................ 1513
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Diagnostic Imaging Obstetrics, 2nd Edition
262. Uterine Rupture .................................................................................................................. 1516
III. Ovary ......................................................................................................................................... 1523
263. Corpus Luteum Cyst............................................................................................................. 1523
264. Theca Lutein Cysts ............................................................................................................... 1526
265. Hyperstimulation Syndrome ................................................................................................ 1532
IV. Gastrointestinal and Genitourinary Tracts .................................................................................. 1539
266. Appendicitis in Pregnancy.................................................................................................... 1539
267. HELLP Syndrome ................................................................................................................. 1542
268. Maternal Hydronephrosis .................................................................................................... 1548

Section 17 - Postpartum Complications ............................................................................................... 1555
269. Retained Products of Conception ............................................................................................ 1555
270. Endometritis ........................................................................................................................... 1558
271. Bladder Flap Hematoma .......................................................................................................... 1561
272. Ovarian Vein Thrombosis ........................................................................................................ 1564
Index .................................................................................................................................................. 1571
0-9 .................................................................................................................................................. 1571
A ..................................................................................................................................................... 1571
B ..................................................................................................................................................... 1573
C ..................................................................................................................................................... 1576
D ..................................................................................................................................................... 1579
E ..................................................................................................................................................... 1581
F ..................................................................................................................................................... 1582
G..................................................................................................................................................... 1584
H..................................................................................................................................................... 1585
I ...................................................................................................................................................... 1588
J ...................................................................................................................................................... 1589
K ..................................................................................................................................................... 1589
L ..................................................................................................................................................... 1589
M .................................................................................................................................................... 1590
N..................................................................................................................................................... 1592
O..................................................................................................................................................... 1593
P ..................................................................................................................................................... 1594
Q .................................................................................................................................................... 1596
R ..................................................................................................................................................... 1596
S ..................................................................................................................................................... 1597
T ..................................................................................................................................................... 1600
U..................................................................................................................................................... 1602
V ..................................................................................................................................................... 1604
W.................................................................................................................................................... 1605

Y ..................................................................................................................................................... 1605
Z ..................................................................................................................................................... 1605

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Diagnostic Imaging Obstetrics, 2nd Edition

Diagnostic Imaging Obstetrics, 2nd Edition
Cover

Authors
Authors
Paula J. Woodward MD
Professor of Radiology
David G. Bragg, MD and Marcia R. Bragg Presidential Endowed
Chair in Oncologic Imaging
University of Utah School of Medicine
Salt Lake City, UT
Anne Kennedy MD
Professor of Radiology
Adjunct Professor of Obstetrics and Gynecology
Executive Vice Chair of Radiology
Co-Director of Maternal Fetal Diagnostic Center
University of Utah School of Medicine
Salt Lake City, UT
Roya Sohaey MD
Professor of Radiology
Professor of Obstetrics and Gynecology
Director of Ultrasound

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Diagnostic Imaging Obstetrics, 2nd Edition
Oregon Health and Science University
Portland, OR
Janice L. B. Byrne MD
Associate Professor of Obstetrics and
Gynecology/Maternal-Fetal Medicine
Adjunct Associate Professor of Pediatrics/Medical Genetics
Director of Fetal-Neonatal Treatment Program
University of Utah School of Medicine
Salt Lake City, UT
Karen Y. Oh MD
Associate Professor of Radiology
Associate Professor of Obstetrics and Gynecology
Director of Breast Imaging
Oregon Health and Science University
Portland, OR
Michael D. Puchalski MD
Associate Professor of Pediatrics
Adjunct Associate Professor of Radiology
Director of Noninvasive Imaging
University of Utah School of Medicine
Salt Lake City, UT
Thomas C. Winter III MD
Professor of Radiology
Adjunct Professor of Obstetrics and Gynecology
Director of Body Imaging
University of Utah School of Medicine

Salt Lake City, UT
Logan A. McLean MD
Neuroradiology Fellow
University of Utah School of Medicine
Salt Lake City, UT
Contributing Authors
Akram M. Shaaban, MBBCh
David Holznagel, MD
Nelangi Pinto, MD
Asha Sarma, BA
Nicole Winkler, MD
Marcia L. Feldkamp, PhD, PA
Antonio E. Frias, Jr., MD
Shawn E. Gurtcheff, MD, MS
Sonographers
Brooke Axberg, RDMS
Jeanne Baker, RDMS
Kara Bridges, RDMS
Jenny Burke, RDMS
Angie Crist, RDMS
Chelsea Day, RDMS
Porsche Fletcher, RDMS
Danielle Galbreath, RDMS
Kristina Gudonaviciute, RDMS
Pam Guy, RDMS
Deanna Hecker, RDMS
Adrian Lethbridge, RDMS
Naomi Maggio, RDMS
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Diagnostic Imaging Obstetrics, 2nd Edition
Johanna Meier, RDMS
April Nelson, RDMS
Sami Newman, RDMS
Christine Sahn, RDMS
Leticia Seals, RDMS
Joanna Semon, RDMS
Amber Tackett, RDMS
Fariba Tehranchi, RDMS
Catherine Townsend, RDMS
Kasey Zimmer-Stucky, RDMS

Dedication
To Robert, Melanie, and Keri.
Family need not be defined by biologic fate but by the choices of loving bonds that we make.
To Anne and Roya (also my family) and my intrepid group of authors—my team—my friends. You bring joy
to the process.
PJW
To “we three”—the blonde, the brunette, and the redhead. Friends and adventurers forever.
AK
To Dave, Brett, and Haley. I am eternally grateful for your support and spirit. You bring me such joy and
mean everything to me. Also, to the original pioneers, Minoo and Manu, for emigrating to the U.S. so I
could “live the dream.”
RS
To Jerry, my husband and best friend of over 30 years, and my terrific son, Matt, without whose love and
understanding of my frequent prolonged absences, I would not be able to do what I do.
To all our wonderful patients, who often in times of great sorrow, graciously gave me permission to
photograph their children.
J LB B

To my husband, Antonio, for being my biggest fan at home and at work, and to our amazing children, Nina
and Diego, who make our family whole and provide endless entertainment.
KYO
To my parents who guided me with a soft but firm hand. The person I am today is because of them. To my
wife, Brenda, and my children, Luli and Tristan—you are the light of my life.
MDP

Preface
Here we go again!
We were so happy with the 1st edition of Diagnostic Imaging: Obstetrics that I couldn't imagine what we
would do in a 2nd edition. But that was 5 long years ago, and much has changed. Imaging has advanced,
new treatment regimens have been implemented, and our understanding of the pathophysiology and
genetics of many congenital diseases has changed. It is a never-ending, exciting journey in which those of
us in fetal imaging are immersed. It was with this excitement that we began to discuss what we wanted to
include in a 2nd edition.
The style of the 1st edition was extremely successful with its succinct, bulleted text yielding more “pearls
per pound” than standard textbooks. We did not want to “mess with success,” so the basic layout remains
the same—but with much, much more.
 New embryology chapters delineate normal fetal development, laying the basis for understanding
developmental anomalies. Each chapter contains detailed labeling of graphics and the normal fetal
structures seen on both ultrasound and MRI.
 New prose introductions exist for the major sections of the book. Our goal was to give the reader a
detailed approach to the abnormal fetus. Each introductory chapter sets up a framework for the
individual diagnoses that follow.

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Diagnostic Imaging Obstetrics, 2nd Edition


More than 30 new diagnoses have been added, making the 2nd edition the most comprehensive
reference text possible. All existing chapters have been meticulously updated to reflect the most
up-to-date information and references on the topic.
 New image galleries exist for each diagnosis—about 2,400 images in the book—and a new ebook
feature with hundreds of additional images is available online.
 With the additional formats introduced for the 2nd edition, we are now able to show expanded
image galleries for common diagnoses, thus allowing the reader to see not only the most common
presentation but also the all-important variants. Each chapter is richly illustrated with graphics;
fetal MRI; 3D, grayscale, and Doppler ultrasound; and, where possible, clinical and/or pathologic
correlation.
This book was written by an extraordinary and diverse group of fetal imaging experts. The authoring team
includes authorities in radiology, perinatology, cardiology, and clinical genetics. The collaborative effort
among the team members elevates each chapter to its highest attainable level of excellence. We are all
dedicated to advancing the understanding and diagnosis of fetal diseases and remain humbly aware of how
devastating these diagnoses can be for the affected family. We share a common passion for making the
correct diagnosis and providing the most complete information possible to families during one of the most
difficult times in their lives. Each chapter was written with the excitement of sharing our collective
knowledge and life's work with you, the reader.
In addition to the physicians who worked on this book, it is important to acknowledge the sonographers
and MR technologists for their fine work, which is used extensively throughout this text. I would also like to
thank the wonderful Amirsys production staff—especially Ashley, Kellie, and Jeff—whose attention to
detail makes everything I do better and the illustrators—Lane, Rich, and Laura—who make this book truly
special.
It is with a great deal of pride that we present to you the 2nd edition of Diagnostic Imaging: Obstetrics.
Paula J. Woodward, MD
Professor of Radiology
David G. Bragg, MD and Marcia R. Bragg Presidential Endowed
Chair in Oncologic Imaging
University of Utah School of Medicine

Salt Lake City, UT

Acknowledgements
Text Editing
Dave L. Chance, MA
Arthur G. Gelsinger, MA
Matthew R. Connelly, MA
Lorna Morring, MS
Alicia M. Moulton, BA
Image Editing
Jeffrey J. Marmorstone, BS
Lisa A. Magar, BS
Medical Editing
Cara C. Heuser, MD
Heather D. Major, MD
Logan A. McLean, MD
Illustrations
Lane R. Bennion, MS
Richard Coombs, MS
Laura C. Sesto, MA
Art Direction and Design
Laura C. Sesto, MA
Associate Editor
Ashley R. Renlund, MA
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Diagnostic Imaging Obstetrics, 2nd Edition
Publishing Lead
Kellie J. Heap, BA

Section 1 - First Trimester
I. Introduction and Overview
1. Embryology and Anatomy of the First Trimester
> Table of Contents > Section 1 - First Trimester > Introduction and Overview > Embryology and Anatomy of
the First Trimester
Embryology and Anatomy of the First Trimester
Anne Kennedy, MD
TERMINOLOGY
Definitions
• 1st trimester covers time from 1st day of last menstrual period to end of 13th post menstrual week
EMBRYOLOGY
Embryologic Events
 1st trimester includes
o Ovulation
o Fertilization
o Cleavage
o Implantation
o Embryonic development
o Organogenesis
o Placental development
o Umbilical cord development
Ovulation
 Primordial follicles → 5-12 primary follicles per cycle
 All but 1 degenerate, leaving a single dominant follicle
 Pituitary gonadotrophin surge → ovulation → oocyte extruded onto ovarian surface
 Oocyte surrounded by tough zona pellucida as well as layers of cumulus cells
 Fimbria sweep oocyte into fallopian tube
 Remaining “empty” follicle becomes corpus luteum producing estrogen and progesterone
Fertilization

 Occurs in fallopian tube
 Oocyte can be fertilized for ˜ 24 hours
 Sperm penetrates oocyte, cell membranes fuse → zygote
 Spermatozoan and oocyte nuclei become male and female pronuclei
 Nuclear membranes disappear, chromosomes replicate in preparation for zygote cleavage
Cleavage
 Zygote → 2 cells → 4 cells → 8 cells → morula → blastocyst
 Several cell divisions result in smaller parts called blastomeres
 At 8 cell stage, compaction occurs with some cells → inner cell mass or embryoblast, some cells →
peripheral trophoblast
o Inner cell mass/embryoblast = embryonic pole of blastocyst
 16-32 blastomeres = morula
 Morula absorbs fluid → central cavity called blastocoele within blastocyst
Implantation
 Blastocyst “hatches” from zona pellucida
 “Naked” blastocyst then interacts directly with maternal endometrium
 Trophoblast cells give rise to membranes and placenta, not embryo proper
o Trophoblast cells at embryonic pole → syncytiotrophoblast, which burrows into
endometrial lining
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Diagnostic Imaging Obstetrics, 2nd Edition
o

Remaining trophoblast cells become cytotrophoblast
 Maternal endometrial cells differentiate into decidual cells in response to
o Progesterone secreted by corpus luteum
o β human chorionic gonadotrophin produced by syncytiotrophoblast
Embryonic Development

 Bilaminar embryonic disc forms when embryoblast splits into epiblast and hypoblast
 Hypoblast = primitive endoderm
o Hypoblast cells migrate around cavity of blastocyst to create primary yolk sac
o Hypoblast + primary yolk sac give rise to extraembryonic mesoderm (loosely associated
cells filling blastocyst cavity around primary yolk sac)
o 2nd wave of migrating hypoblast cells create secondary yolk sac, which displaces primary
yolk sac
o Extraembryonic mesoderm splits into 2 layers, creating chorionic cavity (extraembryonic
coelom)
o Chorionic cavity separates embryo/amnion/yolk sac from chorion (outer wall of blastocyst)
 Epiblast contributes to embryo and gives rise to amnion
o Fluid collects between epiblast and overlying trophoblast → cavity
o Layer of epiblast differentiates into amniotic membrane separating new cavity from
cytotrophoblast
 Trilaminar disc
o Develops by process of gastrulation, which moves cells to new locations with resulting
induction
o 3 primary germ layers = ectoderm, mesoderm, endoderm
o Body axes also determined by gastrulation
 Disc elongates and folds → series of tubular structures → major organ systems
 Ectoderm → neural plate → neural tube + neural crest cells
o Neural tube → brain and spinal cord
o Neural crest cells migrate from neural tube → many differing structures and cell types
 Mesoderm
o Head mesoderm → muscles of face, jaw, and throat
o Notochordal process
o Cardiogenic mesoderm
o Somites → most of axial skeleton
o Intermediate mesoderm → genitourinary system
o Lateral plate mesoderm → abdominal wall and gut walls

 Endoderm
o Foregut, midgut, hindgut (oropharyngeal membrane → mouth)
Organogenesis
 Central nervous system
o Arises from neural folds → neural tube + neural crest
 Cranial/rostral 2/3 of neural tube → brain
 Caudal 1/3 of neural tube → spinal cord, nerves
 Neural crest → peripheral nerves, autonomic nervous system
 Cardiovascular system
o Arises from cardiac tube → heart and great vessels
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o
o
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Cardiogenic precursors form 1° heart field at cranial end of embryo
Lateral endocardial tubes brought together by embryonic folding → primitive heart tube
Looping, remodeling, septation of primitive heart tube → definitive 4 chamber heart
Conotruncus = primitive outflow tract that splits → ventricular outflow tracts
Respiratory system
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Diagnostic Imaging Obstetrics, 2nd Edition
o

Foregut → respiratory diverticulum → 1° bronchial buds → 3 right + 2 left 2° bronchial buds
→ terminal bronchioles → respiratory bronchioles → primitive alveoli
 Gastrointestinal system
o Early embryonic folding → endodermal tube → foregut, midgut, hindgut
o Foregut (blind-ending at oropharyngeal membrane) → esophagus, stomach, proximal
duodenum
 Liver, gallbladder, cystic duct, and pancreas arise from duodenal diverticula
o Midgut (initially open to yolk sac) → distal duodenum to proximal 2/3 transverse colon
 Future ileum elongates rapidly → 1° intestinal loop, which herniates into base of
umbilical cord rotating 90°
 During retraction into peritoneal cavity, additional 180° rotation secures normal
bowl orientation with cecum right, duodenojejunal flexure left
o Hindgut (blind-ending at cloacal membrane) → distal 1/3 transverse colon to rectum
 Terminal expansion of primitive hindgut tube → cloaca
 Urorectal septum divides cloaca into urogenital sinus + dorsal anorectal canal
 Genitourinary system
o Intermediate mesoderm → pronephros, mesonephros, metanephros
 Mesonephros → rudimentary kidneys connected to cloaca by mesonephric ducts
 Mesonephric ducts → ureteral bud → collecting system
 Ureteral bud connection to metanephric blastema → induction of nephron
formation
o Bladder arises from cloaca and allantois
o Bladder separated from rectum by urogenital sinus
 Musculoskeletal system
o Upper and lower extremities develop from individual limb buds
Placental Development
 Chorionic sac initially covered in villi, atrophy of those adjacent to uterine cavity → chorion laeve
 In villi adjacent to implantation site, burrowing syncytiotrophoblast develops trophoblastic lacunae
o Adjacent maternal capillaries expand → maternal sinusoids, anastomose with trophoblastic
lacunae

o Budding/proliferation of cytotrophoblast into syncytiotrophoblast and maternal lacunae →
mature tertiary villi
o Tertiary villi contain fully differentiated blood vessels for gas exchange in chorion
frondosum
 Chorion frondosum + decidua basalis = placenta
Umbilical Cord Development
 Embryonic disc lies between amnion and yolk sac
 Embryo initially connected to chorion by connecting stalk, which arises from extraembryonic
mesoderm
o Allantois (endodermal hindgut diverticulum) arises as outpouching of yolk sac
o Allantois and allantoic vessels extend into connecting stalk (become umbilical vessels)
 Embryonic growth and folding result in blind-ended foregut and hindgut tubes with midgut open to
yolk sac
o As body wall forms by lateral folding and midgut becomes tubular, yolk sac is “pinched off”
o Narrow elongated neck of yolk sac = vitelline duct, which connects yolk sac to closing
midgut tube
 As embryo enlarges and folds, amniotic cavity expands to encompass embryo completely except at
umbilical ring
o Connecting stalk, allantois, vitelline duct become incorporated as umbilical cord
o Amnion continues to enlarge and forms a tubular covering over incorporated cord
elements → dense epithelial covering
 Progressive cord elongation and coiling occur with embryonic/fetal growth and movement
ANATOMY-BASED IMAGING ISSUES
Key Concepts or Questions
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Diagnostic Imaging Obstetrics, 2nd Edition
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Developmental milestones (in weeks post LMP)
o Gestational sac (intradecidual sac sign) visible by 4-4.5 weeks
o Yolk sac visible by 5-5.5 weeks
o Distinct embryo with cardiac activity visible by 6-6.5 weeks
Developmental milestones based on mean sac diameter (MSD)
o Yolk sac should be visible if MSD > 10 mm by endovaginal (EV) scan
o Embryo should be visible if MSD > 18 mm EV
“5 alive” rule: Embryo of > 5 mm in length must have cardiac activity
o If embryo seen within visible amnion, cardiac activity should be present (expanded amnion
sign)
Gestational age assessment most accurate in 1st trimester
o Biological variations take effect after 13 weeks
Determination of chorionicity in multiple pregnancies
o Most important factor in prognosis
Is there evidence of increased risk for aneuploidy?
o 11-13 week scan can be used to adjust a priori risk of aneuploidy, determine need for
invasive testing
Is the anatomy normal?

o Organogenesis is complete by end of 13th week
o Use EV sonography for best resolution
1st trimester is a time of complex cell multiplication and differentiation
o Great potential for error if normal processes are not clearly understood

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Image Gallery
OVULATION AND FERTILIZATION

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Diagnostic Imaging Obstetrics, 2nd Edition

(Top) During the follicular phase of the menstrual cycle, several follicles begin to develop; one becomes
dominant and eventually a mature oocyte is extruded from the ovarian surface at the time of ovulation.
The remaining follicle becomes the corpus luteum, which produces progesterone and helps to maintain the
early pregnancy until the placenta is formed. If fertilization does not occur, the corpus luteum degenerates
into a corpus albicans. (Bottom) The oocyte is swept into the fallopian tube where it is fertilized. The
fertilized ovum divides repeatedly during passage along the tube such that, by the time it reaches the
endometrial cavity, a blastocyst has formed. The blastocyst “hatches” from the zona pellucida and implants
into the maternal endometrium.
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CLEAVAGE AND IMPLANTATION

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Diagnostic Imaging Obstetrics, 2nd Edition

(Top) While the dividing zygote is still in the fallopian tube (8 cell stage), cells differentiate into embryoblast
and trophoblast. Syncytiotrophoblast interacts with the endometrium to form the placenta; the remainder
is the cytotrophoblast. Embryoblast cells will give rise to the embryo, amnion, and yolk sac. (Middle) The
embryoblast splits into 2 layers: Epiblast and hypoblast. The hypoblast gives rise to the primary and
secondary yolk sacs and extraembryonic mesoderm. The latter splits, forming the chorionic cavity. The
epiblast gives rise to the embryo and the amnion. (Bottom) As the primary yolk sac involutes, the
secondary yolk sac develops. It is the secondary yolk sac that is visible sonographically; however, by
convention, it is usually referred to as simply “the yolk sac” on ultrasound images. The chorionic cavity
enlarges. The embryo is still a bilaminar disc.
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INTRADECIDUAL SAC SIGN

(Top) The graphic illustrates the earliest sonographic manifestation of the embryological development
illustrated previously. The gestational sac has burrowed into the decidualized endometrium, creating an
asymmetrically placed echogenic ring with a lucent center. This is known as the intradecidual sac sign.
(Bottom) The intradecidual sac sign is seen on this transvaginal image. Note the echogenic ring formed by
the intradecidual gestational sac, which is eccentric to the line created by apposition of the endometrial
surfaces. There is no fluid in the endometrial cavity. No internal structures are seen within the gestational
sac, but this is normal at this gestational age, as the developing structures are beyond the resolution of
even high-frequency vaginal transducers.
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DOUBLE DECIDUAL SAC SIGN

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Diagnostic Imaging Obstetrics, 2nd Edition

(Top) This graphic illustrates the double decidual sac sign. This is seen when the enlarging gestational sac
protrudes from the site of implantation and starts to expand into the uterine cavity, exerting mass effect on
the opposite uterine wall. The decidua covering the expanding sac is decidua capsularis; that which is being
pushed ahead of the expanding sac is the decidua parietalis. The decidua basalis is where the sac is
adherent to the uterine wall and marks the site where the placenta will develop. Internal structures can
now be seen, especially with the use of vaginal transducers. (Bottom) The decidual layers are easily seen on
this transvaginal scan. The concentric rings created by the decidua capsularis and parietalis create the
double decidual sac sign. A yolk sac and embryo were visible on other scan planes; this image was taken to
illustrate the double decidual sac sign.
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EMBRYONIC DEVELOPMENT: 6 WEEKS
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Diagnostic Imaging Obstetrics, 2nd Edition

(Top) The graphic illustrates normal early development. The embryo is intimately associated with the yolk
sac such that the amnion and yolk sac appear as a “double bleb” with the embryo sandwiched between
them. The embryo is within the amniotic sac; both embryo and yolk sac are inside the chorionic sac. The
villi adjacent to the uterine cavity atrophy creating the smooth chorion laeve. (Middle) Transvaginal scan
shows an embryo appearing as a “dot” at the edge of the yolk sac. This can be described as the diamond
ring sign. The amnion, though present, is not yet visible. (Bottom) Later in gestation, the amnion can be
seen separate from the yolk sac. The embryo has elongated and is beginning to assume the “grain of rice”
appearance. It is inside the amniotic cavity but still intimately associated with the yolk sac, which is in

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continuity with the embryonic midgut at this stage.
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EMBRYONIC DEVELOPMENT: 8 WEEKS

(Top) Curvature and folding of the embryo result in closure of the abdominal wall and pinching off of the
yolk sac. The elongated neck forms the vitelline duct. Eventually the yolk sac separates from the embryo,
dropping into the chorionic cavity. At the same time it becomes clear which end of the embryo is which,
and limb buds starts to form. The chorion adjacent to the uterine cavity is now completely smooth.
Chorionic villi in the developing placenta become more complex in structure. (Middle) Transvaginal scan at
8 weeks shows the rhombencephalic vesicle at the “crown” end. This normal hindbrain development
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Diagnostic Imaging Obstetrics, 2nd Edition
should not be confused with pathology. The embryo is within the amniotic cavity. (Bottom) Progressive
elongation and folding result in a more kidney-bean-shaped embryo. This 3D surface-rendered image
clearly shows the crown and rump ends and the separated yolk sac.
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EMBRYONIC DEVELOPMENT: 9 WEEKS

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Diagnostic Imaging Obstetrics, 2nd Edition

(Top) The graphic illustrates continued embryonic development; the limb buds are evident, the head has
grown dramatically, and the embryo is assuming a recognizable human form. The umbilical cord forms as a
result of fusion of the vitelline duct, allantois, and connecting stalk. Once formed, it elongates rapidly until
the embryo is suspended within the enlarging amniotic sac. Cord elongation allows for free mobility of the
developing fetus. (Middle) Transvaginal scans allow visualization of these changes. The thick, short
developing umbilical cord is seen extending from the abdominal wall, and the “crown” end of the embryo is
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Diagnostic Imaging Obstetrics, 2nd Edition
much different in appearance from the “rump.” (Bottom) A coronal view of the embryo shows the
relationship of the head to the torso. All 4 limb buds are identified, and part of the rhombencephalic vesicle
is seen in the developing cranium.
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EMBRYONIC DEVELOPMENT: 10-13 WEEKS

(Top) Toward the end of the 1st trimester, the amnion fills the chorionic cavity. The membranes do not
“fuse” until 14-16 weeks. As the limbs develop and cranial development continues, the embryo becomes
recognizably human. The placenta continues to grow, and the chorionic villi develop an increasingly
complex branching pattern. (Middle) At 10 weeks, there is some residual herniation of bowel into the base
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