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

(BQ) Part 2 book Diagnostic imaging obstetrics presents the following contents: Genitourinary tract, musculoskeletal, placenta, membranes and umbilical cord, multiple gestations, aneuploidy, syndromes and multisystem disorders, infection, fluid, growth and well-being, maternal conditions in pregnancy, postpartum complications.

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

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

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

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

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

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

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

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

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

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

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

 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

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

 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

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

P.1:3

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

 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

P.1:4

Image Gallery

OVULATION AND FERTILIZATION

(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

P.1:5

CLEAVAGE AND IMPLANTATION

(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

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

P.1:7

DOUBLE DECIDUAL SAC SIGN

(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

(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

continuity with the embryonic midgut at this stage

P.1:9

EMBRYONIC DEVELOPMENT: 8 WEEKS

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

P.1:10

EMBRYONIC DEVELOPMENT: 9 WEEKS

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

P.1:11

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

of the cord The embryo is freely suspended within the amniotic sac by the cord, which already shows evidence of coiling The yolk sac will be obliterated as the amnion apposes to the chorion (Bottom) 3D surface rendering shows recognizable cranium, torso, and extremity contours in this 11-week fetus The profile is clear, bilateral upper and lower extremities are present, and in real time, the fetus can be

observed to move within the pool of amniotic fluid

P.1:12

ABDOMINAL WALL AND GI TRACT

and there is no residual bowel herniation Three of the extremities are seen, cranial contour is normal, and the cord is already coiled

P.1:13

UMBILICAL CORD DEVELOPMENT

(Top) The graphic illustrates fetal circulation in which oxygenated blood from the placenta returns to the fetus via the umbilical vein The umbilical vein courses through the left lobe of the liver to the left portal

vein, across the ductus venosus into the inferior vena cava The umbilical cord also contains 2 arteries, which arise from the internal iliac arteries (Middle) At 10 weeks, flow is evident on color Doppler

evaluation The coiled arrangement of the arteries and vein is already established (Bottom) This sagittal image of a 9-week embryo shows the umbilical vein as it passes through the edge of the falciform ligament

to reach the liver, ductus venosus, inferior vena cava, and right atrium Blood flow is also seen in the descending aorta Color and power Doppler deposit less energy than spectral Doppler, but all should be used sparingly in the embryo

2 Approach to the First Trimester

> Table of Contents > Section 1 - First Trimester > Introduction and Overview > Approach to the First Trimester

Approach to the First Trimester

Anne Kennedy, MD

Imaging Techniques and Normal Anatomy

Endovaginal ultrasound (EV US) is the imaging modality of choice in evaluation of the first trimester

pregnancy It provides the highest resolution images and is most comfortable for the patient as it is not necessary to fill the bladder prior to imaging In rare instances transabdominal ultrasound (TA US) may be sufficient; for example, in cases where there is a known intrauterine pregnancy (IUP) but fetal cardiac activity is not heard, TA US may be used to verify that the embryo is still alive This limited examination is often performed in patients with a history of recurrent abortion and is more for maternal reassurance than accurate assessment of embryonic and fetal development

The sonologist performing the examination must be familiar with the appearances of normal early

pregnancy and the appearances of ectopic gestations and failed pregnancies Misunderstanding of normal anatomy and developmental milestones may lead to incorrect diagnosis and incorrect treatment

The earliest sign of an IUP is the intradecidual sac sign (IDSS) seen at the time of implantation when the early embryo “burrows” into decidualized endometrium This is seen as a spherical, cystic structure

eccentric to the central echo of the uterine cavity

The next stage of development that becomes visible is referred to as the double decidual sac sign (DDSS) in which the expanding gestational sac creates two echogenic rings The decidual capsularis is the outer expansion of the trophoblastic tissue; it creates the inner ring, whereas the decidual parietalis of the surrounding uterine cavity creates the second, outer ring A focal area of thickened decidua at the site of implantation is referred to as the decidua basalis

Following visualization of the DDSS, the next visible milestone seen sonographically is the yolk sac The amnion forms embryologically before the yolk sac, but it is such a thin, delicate membrane that even with

EV US it is the latter of the two structures to be resolved The yolk sac has a distinct wall, is smooth in outline, and spherical in shape with a maximum diameter of 6 mm

The embryo is first resolved as a focal thickening at the circumference of the yolk sac Cardiac activity may

be seen as a “flickering” in this area before the embryo is sufficiently large enough to allow accurate measurement of length Once the embryo is discretely resolved, the longest axis is measured and referred

to as the crown rump length As the neural tube elongates and folds it becomes apparent which end of the embryo is actually the head or crown end As the embryo enlarges, the amnion becomes visible

surrounding it This is a very important observation; the embryo is always inside the amnion, and the yolk sac is always outside the amnion

As continued growth and development progress, the embryo visibly changes from a “dot” to a “grain of rice” to a more “kidney bean” shaped structure Then limb buds develop, the head, torso, and extremities

vs complete abortion vs ectopic pregnancy The term pregnancy of unknown location (PUL) has been coined to describe the situation in which there is a chemical pregnancy with no evidence of either an IUP or

an ectopic by EV US Thus it is vital that the sonologist knows the signs of intrauterine pregnancy as well as those of ectopic pregnancy In particular it is important to evaluate the adnexa carefully for mass, tubal ring, and echogenic free fluid The normal corpus luteum should not be mistaken for an ectopic pregnancy Prominent flow around the corpus luteum is a normal observation and should not be confused with the

“ring of fire” sign of trophoblastic flow around an ectopic gestation An oval or flattened fluid collection placed centrally in the uterine cavity is often seen with ectopic gestation; this is referred to as a pseudosac The pseudosac should not be confused with the IDSS or DDSS signs of a normal IUP

If the patient is stable it is always wise to be conservative Normal early pregnancies develop in a standard manner with rapid changes in a short time frame An intradecidual sac sign progresses quickly to a double decidual sac sign if the pregnancy is normal Similarly in the case of PUL, either an IUP or an ectopic

gestation should become visible within days if not apparent at the time of the initial presentation

It is also important to be aware of the possibility of heterotopic pregnancy in which an IUP coexists with an ectopic gestation This is rare in the normal population but is not uncommon in patients with risk factors such as tubal scarring or a history of assisted reproduction Medical management is contraindicated in heterotopic pregnancy as systemic methotrexate administration would be harmful to the IUP

How many embryos are there?

Once the diagnosis of IUP is established, it is essential to scan the entire pelvis to document the number of embryos Müllerian duct anomalies are a possible pitfall; if an incomplete scan is performed, a bicornuate

or septate uterus may not be appreciated Multiple pregnancies may occur with implantation in both horns

or one

Gestational sacs have a very typical appearance and perigestational hemorrhage (PGH) should not be confused with an additional pregnancy A PGH is usually crescentic in shape, located deep to the echogenic ring of chorionic tissue, and although the area of hemorrhage may be inhomogeneous, there will be no evidence of an embryo or yolk sac

If there is a multiple gestation, it is important to determine chorionicity as early as possible The chorion forms a thick echogenic ring that completely encompasses the embryo If more than one embryo is seen within a single chorionic ring, the pregnancy is monochorionic The next step is to determine amnionicity

As mentioned, the amnion is a very delicate membrane that may not be seen in early gestation However, the number of yolk sacs parallels the number of amnions; therefore, if there are two embryos and two yolk sacs, it is highly likely

P.1:15

that the pregnancy is a monochorionic diamniotic twin gestation If only one yolk sac is seen after a

complete sweep through the gestational sac in longitudinal and transverse planes, the pregnancy may be monoamniotic or the embryos may be conjoined Conjoined twins maintain a fixed relationship to each other and have an area of contiguous skin covering differentiating them from monoamniotic twins that move independently of each other and are completely separate, even if mobility is limited by cord

entanglement Chorionicity is the single most important prognostic factor in multiple gestations and should therefore be assessed in every case

What is the gestational age?

The “normal” menstrual cycle is 28 days, and the assumption is made that conception occurs on day 14 of the cycle Some patients may be unsure of dates or may have an irregular cycle or conceive while breast feeding or using oral contraceptives In this circumstance first trimester ultrasound is the most accurate way to determine gestational age Biological variation does not take effect until after the 13th week of gestation First trimester ultrasound establishes dates to within one week thereby allowing accurate assessment of growth in the second and third trimesters By the third trimester sonographic measurements predict gestational age with a ± 3 week range such that determination of large or small for dates fetal size

is challenging

Is the pregnancy normal?

Modern equipment provides exquisite resolution and allows for quite detailed anatomic assessment by the end of the first trimester In families with autosomal recessive traits, early scans may allow diagnosis of recurrence of conditions such as Meckel-Gruber syndrome A woman with a history of a fetus with trisomy

13 will be much reassured to know that there is no evidence of alobar holoprosencephaly at 13 weeks Similarly first trimester screening for aneuploidy has become increasingly sophisticated with the use of ultrasound Between 11 and 13 weeks, the nuchal translucency, facial angle, tricuspid regurgitation, ductus venosus flow, and assessment of nasal bone can be used to select a group of fetuses at higher risk for aneuploidy These patients may wish to have a diagnostic procedure such as chorionic villus sampling or amniocentesis The combination of sonographic and biochemical testing increases the specificity of

screening and minimizes the risk of loss caused by invasive testing on normal pregnancies

In multiple gestations, evaluation of nuchal translucency and ductus venosus flow can be used to detect monochorionic twins at increased risk for complications such as twin twin transfusion syndrome as well as for aneuploidy screening

Assessment of uterine artery Doppler waveforms may be helpful to select patients at increased risk for eclamptic toxemia thus allowing more intensive surveillance

pre-Many anomalies can now be confidently diagnosed by the end of the first trimester These include neural tube defects, abdominal wall defects, limb reduction abnormalities, and some brain malformations, such as the holoprosencephaly spectrum

What about the uterus and adnexa?

The first trimester scan is not restricted to evaluation of the embryo/fetus It is important to look at the uterine contour, document fibroid size and location, assess for possible müllerian duct anomalies, and note the presence of large nabothian cysts or Gartner duct cysts that might cause a confusing appearance on TA

US evaluation of the cervix later in gestation

The majority of adnexal masses seen in pregnancy are benign However, particularly with advancing

maternal age, ovarian neoplasms may be detected Even a benign neoplasm, such as teratoma, may

undergo torsion If the presence of an adnexal mass is known, the evaluation of a patient with acute onset

of abdominal or pelvic pain in pregnancy is much simplified

The appearance of the corpus luteum is highly variable from a small, crenulated, involuting thick-walled cyst to the complex appearance seen with hemorrhage and the larger corpus luteal cyst, which may reach several centimeters in diameter The latter should have resolved by 16 weeks post LMP

Clinical Implications

First trimester scans provide accurate information on gestational age, assist in screening for aneuploidy, exclude several major malformations, and are vital in determination of chorionicity in multiple pregnancies P.1:16

Mean Sac Diameter

Yolk sac visible MSD > 10 mm Embryo visible MSD > 18 mm Embryo visible If amnion visible

Cardiac Activity

If embryo > 5 mm in length

(Left) Transvaginal ultrasound shows the IDSS of a very early pregnancy “burrowing” into the

decidualized endometrium Note the eccentric placement with respect to the uterine midline echo (Right) Transvaginal ultrasound at 5 weeks 1 day post LMP shows the DDSS with decidua capsularis

surrounding the expanding chorionic sac, decidua parietalis formed by the decidualized endometrium

of the uterine cavity, and decidua basalis at the implantation site

(Left) Transvaginal ultrasound sagittal scans show the IDSS and the DDSS of early pregnancy in comparison to the next image, which shows a pseudosac of ectopic pregnancy (Right) Transvaginal sagittal uterus view shows a fluid collection that mimics a gestational sac (i.e., a pseudosac) The collection is clearly within the endometrial cavity but does not have the features of an IUP Echogenic fluid in the cul de sac is from intraperitoneal hemorrhage due to a bleeding ectopic

(Left) Transvaginal ultrasound of an ectopic pregnancy shows the ovary , the empty uterus , and an adnexal mass Color Doppler shows flow around the mass, often referred to as the “ring of fire” sign of flow in the trophoblastic tissue surrounding an ectopic (Right) Color Doppler ultrasound shows flow around the normal corpus luteum , which maintains the pregnancy until the placenta forms This is a normal finding and should not be confused with an ectopic pregnancy

P.1:17

(Left) Transvaginal ultrasound shows the “dot” appearance of the embryo as a thickening at the

periphery of the yolk sac (Right) 3D reformation at 6 weeks shows the “grain of rice” appearance of the embryo Note that the yolk sac is still close to the embryo as though the embryo is carrying a backpack

(Left) 3D reformation at 7 weeks shows the “kidney bean” shaped embryo seen once the cranial structures start to enlarge It is now apparent which end is the crown and which is the rump Note that the umbilical cord is also visible (Right) Transvaginal ultrasound at 9 weeks shows the embryo within the amnion , which will expand to obliterate the chorionic cavity and appose to the chorion Upper and lower extremity limb buds are visualized at this gestational age

(Left) Transabdominal ultrasound at 9 weeks shows 2 embryos within the uterus Each is surrounded by

a thick chorionic membrane ; thus, this is indisputably a dichorionic twin gestation The 1st trimester is the best and easiest time to determine chorionicity and amnionicity (Right) 3D reformation at the end of the 1st trimester shows a recognizable “mini human.” Organogenesis is complete; there is continued growth and development of all organ systems during the rest of the pregnancy and through childhood

II Intrauterine Gestation

3 Failed First Trimester Pregnancy

> Table of Contents > Section 1 - First Trimester > Intrauterine Gestation > Failed First Trimester PregnancyFailed First Trimester Pregnancy

Anne Kennedy, MD

Key Facts

Terminology

 Gestational sac of discriminatory size without visible embryo

 Gestational sac with visible embryo (> 5 mm) and no cardiac activity

Imaging

 Use endovaginal (EV) sonography

 Gestational sac without identifiable content

o Mean sac diameter > 10 mm EV without yolk sac

o Mean sac diameter > 18 mm EV without embryo

 Empty amnion sign

o Visible amnion without embryo

 Expanded amnion sign

o Amnion visible surrounding embryo but no cardiac activity

 Yolk stalk sign

o Yolk sac distant from embryo rather than adjacent

 Irregular sac contour (flattened, poor decidual reaction)

 Sac positioned low in uterus

Top Differential Diagnoses

 Very early intrauterine pregnancy

 Pseudosac of ectopic pregnancy

 Retained products of conception

 Gestational trophoblastic disease

Diagnostic Checklist

 The term “failed 1st trimester pregnancy” simplifies terminology

 If in doubt, wait and see

o Normal pregnancies grow in predictable manner

o MSD increases by 1 mm per day

o Schedule follow-up for time when gestational sac should have reached discriminatory threshold

(Left) Transvaginal ultrasound shows the empty amnion sign with a collapsed yolk sac , poor

decidual reaction , and little flow around the gestational sac (Right) Transvaginal ultrasound shows a small, echogenic, 6-week-sized embryo without cardiac activity within an amniotic sac A large yolk sac is seen The yolk sac is intimately related to the midgut in a normal 6-week embryo and should not

(Left) Transvaginal ultrasound shows an empty amnion (calipers) within the chorionic sac The yolk sac was seen separately on other scan planes Subchorionic hemorrhage was present; this pregnancy ended

in spontaneous abortion (Right) Transvaginal ultrasound shows an irregular, flattened, empty sac

surrounded by subchorionic hemorrhage The sac is low in the uterus (cervical canal ), and this pregnancy also ended in a spontaneous abortion

 Sac size must have reached discriminatory threshold to diagnose anembryonic pregnancy

o Mean sac diameter > 10 mm endovaginal (EV) without yolk sac

o Mean sac diameter > 18 mm EV without embryo

 Exact threshold is controversial and varies in the literature; ranges from 16-20 mm

 “5 alive” rule

o Embryo > 5 mm crown rump length (CRL) must have cardiac activity

 If vaginal bleeding, new data suggests lack of cardiac activity = demise, regardless

of CRL Ultrasonographic Findings

 Grayscale ultrasound

o General findings

 Abnormal sac contour

 Sac positioned low in uterus

 Poor decidual reaction

o Specific signs of failed pregnancy

 Empty amnion sign

 Visible amnion without embryo

 In normal pregnancy, embryo 1st seen as focal thickening on yolk sac

 Yolk sac forms after amnion but is easier to see

 Amnion then becomes visible, enlarging rapidly to envelop embryo

 Yolk sac eventually obliterated as amnion fuses with chorion

 Expanded amnion sign

 Amnion visible surrounding embryo

 No cardiac activity → embryonic demise regardless of CRL

 Yolk stalk sign

 Yolk sac distant from embryo rather than adjacent (embryo normally

“wears” yolk sac like small backpack)

 Embryo without cardiac activity → demise regardless of CRL

o Complete abortion

 Empty uterus

 Conclusive if prior documentation of intrauterine pregnancy (IUP)

 No intraperitoneal blood

 Thin endometrial echo complex

 Falling β human chorionic gonadotrophin (β-hCG)

 Color Doppler

o Poor color Doppler signal around sac

 Use Doppler to support abnormal diagnosis

 Doppler delivers greater energy with theoretical risks to developing embryo from heating and cavitation

 If possibility of normal early gestation, follow-up with grayscale rather than Doppler

Imaging Recommendations

 Use EV sonography

o Better resolution

o More confidence in diagnosis

 Be sure to scan through entire uterus in longitudinal and transverse planes

o Must look carefully for yolk sac, embryo

o Avoid missing multiple gestations

 Measure mean sac diameter by averaging 3 planes

o Do not include chorion

 Check menstrual history

o Verify date of last menstrual period (LMP)

o Is cycle regular?

o What is cycle length?

 If normal early pregnancy is a possibility, follow-up at intervals timed to normal milestones

o Know anatomy and developmental stages

 “Double bleb”: Embryonic disc between amnion and yolk sac

 Yolk sac, amnion, and embryo should be visible by 7 weeks post LMP

 Embryo lies inside amniotic cavity

 Yolk sac lies outside amniotic cavity

 Normal yolk sac round in shape

 Normal yolk sac ≤ 6 mm diameter DIFFERENTIAL DIAGNOSIS

Normal Early Intrauterine Pregnancy (IUP)

 Intradecidual sac sign

o Spherical, single, echogenic ring “burrowed” into decidualized endometrium

 Double decidual sac sign (DDSS)

o 2 thick echogenic rings of decidual reaction project into uterine cavity

 No DDSS

Retained Products of Conception (RPOC)

 Disorganized material in uterine cavity

o Echogenic material with flow on color Doppler → most likely RPOC

o Retained clot is usually hypoechoic, nonperfused

o No recognizable gestational sac

Gestational Trophoblastic Disease

 Classic hydatidiform mole has “Swiss cheese” appearance

P.1:20

 Early in 1st trimester may just see amorphous tissue or abnormal-appearing gestational sac

 May see associated ovarian theca lutein cysts

Perigestational Hemorrhage

• Crescentic fluid collection around periphery of gestational sac ± living embryo

Pregnancy of Unknown Location (PUL)

 Positive pregnancy test, no signs of intra- or extrauterine pregnancy on EV scans

o May be due to complete abortion; if so, beta (β-hCG) falls to zero

 PUL do not require intervention and will resolve spontaneously if

o Initial serum progesterone level is < 20 nmol/L or

o 48-hour β-hCG ratio is < 0.87 (i.e., a serum β-hCG falls > 13%)

PATHOLOGY ˜

General Features

 Etiology

o Failure of implantation

o Failure of embryo to develop

o Early demise ± resorption of embryonic pole

 60% of spontaneous abortions < 12 weeks due to abnormal chromosomes

 May be asymptomatic with diagnosis made during routine 1st trimester scan

 If spontaneous miscarriage imminent

o 30-60% documented elevations of β-hCG end as failed pregnancy

o Up to 20% of confirmed 1st trimester pregnancies end in spontaneous abortion

o Pathology series of abnormal early pregnancies

 35% anembryonic

 54% early loss (cause not specified)

 11% gestational trophoblastic disease

o Groups with increased incidence of early pregnancy failure

 Advanced maternal age

 History of recurrent abortions

 Poor diabetic control

Natural History & Prognosis

 Random event

 No specific recurrence risk

 Threatened abortion occurs in 25% of 1st trimester pregnancies

Treatment

 Wait and see: Most will spontaneously abort without treatment

 Vaginal misoprostol → successful evacuation of uterus in majority of patients

o Many patients prefer definitive treatment to expectant management

o Some will require curettage, but overall expect 50% reduction in need for surgical

management

 EV US-guided gestational sac aspiration

o Described in assisted reproduction cohort

 More effective than conservative management

 Less invasive than dilatation and curettage

 High probability of obtaining noncontaminated tissue for karyotype

 Suction curettage

o Small associated risk of excessive bleeding, uterine perforation, synechiae development DIAGNOSTIC CHECKLIST

Consider

 Abnormalities common in early pregnancy

 Diagnosis of failed pregnancy depends on knowledge of normal early pregnancy milestones

 If in doubt, wait and see

o Normal pregnancies grow in predictable manner

o MSD increases by 1 mm per day

o Schedule follow-up for time when gestational sac should have reached discriminatory threshold

Image Interpretation Pearls

 Empty amnion sign is specific indicator of anembryonic gestation

 Expanded amnion sign is specific indicator of embryonic demise

Reporting Tips

 The term “failed 1st trimester pregnancy” simplifies terminology

o Avoids confusion with terms such as blighted ovum, missed abortion

5 Mitwally MF et al: Gestational sac aspiration: a novel alternative to dilation and evacuation for

management of early pregnancy failure J Minim Invasive Gynecol 13(4):296-301, 2006

P.1:21

(Left) Transvaginal ultrasound shows the expanded amnion sign with a dead embryo and a

collapsed yolk sac (calipers) New data show that if an amnion is visible around an embryo and there is no heartbeat, it is a embryonic demise regardless of the CRL (Right) Transvaginal ultrasound shows a dead embryo , which is visually small for the size of the gestational sac Note that in this case the yolk sac

is calcified; abnormalities of the yolk sac are not uncommon in early pregnancy failure

(Left) Transvaginal ultrasound shows the empty amnion sign There is poor flow surrounding the gestational sac, and the hypoechoic spaces in the chorionic tissue are due to hydropic chorionic villi (Right) Transvaginal ultrasound shows a flattened gestational sac within the upper cervical canal Earlier scans in this pregnancy (not shown) had demonstrated a double decidual sac sign with the sac implanted normally in the fundal uterine cavity

(Left) Transvaginal ultrasound shows an irregular, flattened gestational sac with poor decidual reaction and no recognizable internal structures (Right) Transvaginal ultrasound shows amorphous material within a poorly perfused gestational sac One week earlier, a live embryo had been visible as well as a chorionic “bump.” The patient had a history of recurrent pregnancy loss and was counseled regarding the poor prognosis Chorionic bump is associated with a 50% loss rate

 Acute hematoma is echogenic

 Subacute hematoma is hypoechoic

 Resolving hematoma is sonolucent

 PGH has no blood flow on Doppler

Top Differential Diagnoses

 Chorioamniotic separation

 Diamniotic twinning

Pathology

 Small PGH surrounds < 20% of sac circumference

 Large PGH surrounds > 50% of sac circumference

Clinical Issues

 3% of all 1st trimester patients have PGH

 20% of patients with vaginal bleeding have PGH

 Presence of a living embryo is most reassuring sign when PGH seen

 PGH associated with maternal/fetal morbidity

o Elevated maternal serum α-fetoprotein (AFP)

o 2nd/3rd trimester abruption (5.6x ↑ risk)

o Preeclampsia (4x ↑ risk)