1. Unusual abdominal wall defects in the fetus
Brian L Shaffer MD
12/15/2018
Associate Professor
Maternal Fetal Medicine
Doernbecher Fetal Care Clinic

2. Disclosures
I have no relevant financial relationships

3. Objectives – Unusual abdominal wall defects in the fetus
Develop a standard approach to abdominal wall defects
Understand testing approaches to certain diagnoses
Review counseling for abdominal wall defects
Cases
40 min

4. Basics – routine abdominal wall views
5 standard views of abdomen
Abdominal circumference – (axial)
Bladder (axial, color)
Renal (axial, sagittal)
Cord insertion (axial)

5. Beyond the basics – Anal dimple
Target appearance
Hyperechoic mucosa, hypoechoic muscular layers
Normal external indentation at anal sphincter
CAN be seen at time of anatomy scan
Study of 13,290 fetuses (16-38 wks)
9,205 cases at wks,
Anus not seen in only 17 cases and 16 had atresia, one idiopathic
Vijayaraghavan et al, Sonographic Depiction of Fetal Anus, JUM 2011;30: 37-45

6. Abdominal wall defects
Common
Gastroschisis
Omphalocele
Less common
Pentalogy of Cantrell
Body Stalk anomaly
Amniotic bands
“Exstrophies”….in GU
Bladder extrophy
OEIS syndrome
Prune belly

7. Gastroschisis – routine to unusual
Gastroschisis is a paramedian defect in the anterior abdominal wall
1 in 5-10,000 live births
Right-sided
Abdominal contents herniate into the amniotic fluid
No covering membrane
Physiologic bowel herniation is normal - should resolve by 12 weeks
Don’t mistake for gastroschisis!

8. Gastroschisis – routine to unusual
Gastroschisis is a paramedian defect in the anterior abdominal wall
1 in 5-10,000 live births
Right-sided
Abdominal contents herniate into the amniotic fluid
No covering membrane
Physiologic bowel herniation is normal - should resolve by 12 weeks
Don’t mistake for gastroschisis!

9. Abdominal wall defects: 1st trimester -- key points
Bowel back in by 12 wks
Liver is NEVER out
Find the cord insertion in 1st trimester
12 wk 3 day NT scan
Gastroschisis
11 wk 3 day dating scan
Omphalocele with liver

10. Gastroschisis – routine to unusual
Etiology unknown (deficient mesoderm?), low risk of aneuploidy, ↑ AFP
Associated with young maternal age, smoking
May be associated with other structural malformations
Simple: most common – no other abnormalities, no sig bowel dilation
Complex: dilated bowel, Other extracorporeal organs, IUGR, Fluid
Intracorporeal dilation – increased risk of atresia
Complications
IUFD (~5%), IUGR (~25%), Atresia (10-15%), Short gut (10-15%)
Poor outcomes are usually related to GI/Resp issues

11. Case: 17 yo G1 – gastroschisis, AFP
35 weeks
12 weeks
17 weeks

12. Intraabdominal bowel dilation raises suspicion for bowel atresia
Case: 24 year old G3P1 with no genetic screening and fetus with increased nuchal fold and gastroschisis
Diagnostic pearl:
Intraabdominal bowel dilation raises suspicion for bowel atresia
29w0d
Dilated loops of bowel within the abdomen
Small gastroschisis
Postnatal diagnosis: Gastroschisis with jejunal, ileal, and colonic atresias
Axial perineum
5 days old
Anal dimple
32w6d

13. The liver is extracorporeal.
Case: 18 yo G1: large fetal abdominal wall defect, normal amniocentesis
The liver is extracorporeal.
Is this an omphalocele?
Axial cord insertion
Complete herniation of the liver
Sagittal cord insertion
20w6d
Not in this case, but you need to consider ruptured omphalocele when the liver is herniated
Remember: In omphalocele, the umbilical cord inserts on the mass, not lateral to it, and there is usually a covering membrane
Herniated stomach
20w6d
Sagittal
24w6d
Sagittal
32w4d

14. Chest circumference <1%ile for gestational age
Case, continued
Axial chest
Coronal right chest
Liver
Right lung
20w6d
Chest circumference <1%ile for gestational age
20w6d
Fetal echocardiogram same day shows large apical muscular VSD (ventricular septal defect)
Small right pleural effusion

15. Infant stillborn after PPROM at 33w6d
Case, continued
Small bowel
Liver
Diagnosis: Giant gastroschisis with extracorporeal liver, bowel, and stomach, plus pulmonary hypoplasia and cardiac defect
Infant stillborn after PPROM at 33w6d
Liver SB
Liver St SB St
Distended stomach
28w4d
32w4d
Distention of the stomach (St) and decompression of the small bowel (SB) raised concern for atresia

16. Gastroschisis
Transient stomach and bladder involvement typical in 3rd trimester …outcome usually not affected

17. Complex Gastroschisis
Intra-corporeal bowel dilation, extra-corporeal bowel decompression
Matted bowel: “pseudo-membrane”

18. Case: 22 year old with no genetic screening and fetal gastroschisis
Axial cord insertion
Diagnostic pearl:
Associated non-GI abnormalities present in up to 20% of gastroschisis
Look out!
Urinary bladder herniation sometimes, but not always, causes hydronephrosis
Urinary bladder herniation in the 3rd trimester
22w6d
32w5d
Sagittal right kidney
Postnatal course: Gastroschisis status post primary fascial repair
Postnatal renal US confirms possible duplex right kidney with mild upper and lower pole pelviectasis
32w5d
Sagittal left kidney
Normal left kidney
32w5d
Right hydronephrosis with probable duplicated collecting system
32w5d

19. Omphalocele: Membrane-covered midline defect at CI site Bowel only
Membrane = amnion + peritoneum
UC on membrane (can be eccentric)
Bowel only
Liver, Ascites
Ascites is common
Associations
Aneuploidy in 30-40% (T18,T13, etc)
MORE LIKELY IF BOWEL ONLY
Syndromes
Beckwith-Weidemann
Pentalogy of Cantrell
Cloacal extrophy/OEIS
Survival 80-90% if isolated

20. Omphalocele + other anomalies
Omphalocele + Left CDH
OEIS (omphalocele, exstrophy, imperforate anus, spinal defect)

21. Omphalocele + other anomalies
Omphalocele + VSD
Pentalogy of Cantrell – sternum, diaphragm, pericardium, the abdominal wall, and the heart

22. Omphalocele: ascites is a common feature

23. Ruptured Omphalocele membrane: rare
First scan
Follow up scan

24. Neonate: Large for GA, macroglossia, hypoglycemia
Case: 36 yo G1 transferred 33 3/7 weeks preterm labor ANI: Polyhydramnios, Fetal S>D, normal GLT
Neonate: Large for GA, macroglossia, hypoglycemia
Large Placenta, hernia

25. Case: 36 yo G1 transferred 33 3/7 weeks preterm labor ANI: Polyhydramnios, Fetal S>D, normal GLT
Omphalocele
Macroglossia
Nephromegaly
Placentomegaly
Werner 2017 Prenat Diag Orofac Malformations

26. Beckwith Wiedemann (BWS) - upd (11)pat
BWS 11p15.5– overgrowth syndrome, macroglossia, organomegaly, embryonal tumors, omphalocele
Neonatal hypoglycemia, earlobe grooves
85% sporadic
Duplicated isodisomic paternal segment of 11p15.5 (20% of BWS), mosaic at single cell  isodisomic
Other modes of inheritance
Conversely, Silver-Russel Syndrome – mat upd 7/11p15
IUGR, relative macrocephaly
In both, recurrence <1%
Mat upd 14

27. Amniotic bands - Disruption
What is correct term? Controversy
amniotic band sequence
amniotic band syndrome
amniotic band disruption complex
limb body wall complex
body wall complex with limb defects
(ADAM) sequence
Amniotic band sequence
Incidence of amniotic band sequence is 1 in 1200 to 1 to 15,000
Considered a chance event, in general not “genetic” or “hereditary”
Recurrence is very low
Severity - where strands are located? how tightly they are wrapped?
Pathogenesis is not firmly established

28. ILE: Amniotic Bands Cord Involvement
Special attention should be made to umbilical cord involvement with amniotic bands. Higher association with fetal demise.
Color Doppler ultrasound: amniotic bands resulting in a clumped cord.

29. Amniotic bands Amniotic band sequence –
BKGD: Recall sac has two layers
- outermost layer- lines the uterus is called the "chorion“
-layer closer to the fetus is called the "amnion"
Inner membrane (amnion) ruptures or tears
No injury to chorion
HYPOTHESIS 1
Fetus is still in fluid, is exposed to the tissue (bands) from the ruptured amnion. Tangles – trouble.
Strands of the amniotic sac that separate and entangle digits, limbs, or other parts of the fetus
Mechanical and vascular disruption

30. Disruption – Amniotic band sequence

31. Disruption – Amniotic bands
HYPOTHESIS 2 Amniotic bands are a secondary phenomena after a primary disruptive event. Disruption of fetal blood flow  generation of amniotic bands and internal and external fetal malformations Why? - There is an increased prevalence of internal visceral anomalies and other anomalies not readily explicable by the ABS - The presence of multiple or severe defects in some ABS cases suggests the occurrence of more than one disruptive factor

32. a a b b Amniotic Bands Fetal entrapment by disrupted amnion
Isolated or multiple defects
Can effect any part of fetus or cord
Extremity findings: amputation, contracture, edema from constriction: cases (a) and (b) demonstrate ILE attaching to hand
Bands appear minimal compared with defect severity a a b b

33. a Body Stalk Anomaly Placenta Bowel Liver
Body Stalk: Fetus is adherent to placenta; amnion in continuity with peritoneum. Thin amniotic bands cause large abdominal wall defect in this case (a). Extracorporeal liver and bowel is seen and the bands mimic an omphalocele membrane.
On the right, ultrasound video of 13 week fetus demonstrates sequelae of body stalk anomaly. Fetus is inseparable from the placenta with lack of normal free-floating loops of umbilical cord, a key differentiating finding from amniotic bands. Large abdominal wall defect with extra-embryonic viscera and ILE.

34. Body Stalk: abdominoschisis + ILE

35. Case: 38 G1 PUV
21 weeks

36. Prune Belly – Imaging pearls
Dramatic dilation of entire collecting system
Entire urethra dilated without obvious point of obstruction – may see urine jet
Oligohydramnios – Normal fluid
Abdominal wall laxity
Small, bell-shaped chest suggestive of pulmonary hypoplasia
Undescended testes

37. Prune Belly: Counseling and management
Incidence: ~4/100,000 live births in US
Characterized by the triad:
Abdominal muscle deficiency
Bilateral cryptorchidism
Severe urinary tract abnormalities
More common in males
Inheritance/Etiology?
Associated with common aneuploidies
Twins, brothers, dominant, mitochondrial, HFN1β
Mesenchymal genetic defect

38. Prune Belly: Counseling and management
Renal – cortical dysplasia, reflux nephropathy and recurrent pyelonephritis
Incomplete nephron differentiation / dilated tubules
Genitourinary abnormalities
Ureters: dilated and tortuous
Bladder: Enlarged with thickened walls
Low voiding pressures, defective urodynamics
Prostate – hypoplastic, dilated urethra
Testicles: cryptorchidism, infertility, germ cells – abnormal with predisposition to tumors
Abdominal wall – aplasia/hypoplasia

39. Prune Belly: Counseling and management
Intervention
Mid-gestation oligo/anhydramnios
Can be difficult to differentiate from LUTO
Vesico-amniotic shunting
Increased survival (6/7)
Overall survival ~70%
1/3 required dialysis / transplant
~50% acceptable renal & bladder function
Survival at one year

40. Prune Belly - Postnatal

41. Final Case: Diagnose by referral phone call
“There’s no bladder…there’s NEVER been a bladder”
“BUT….The fluid is normal”
“I can’t tell the sex of the fetus”
Summary: no bladder, normal fluid, DSD (disorder of sexual development…previously called ambiguous genitalia)
DIAGNOSIS?????

43. Bladder Exstrophy Abdominal wall defect Exposed bladder Associations
Inferior to UCI site
UCI is lower than normal (not easy to tell)
Exposed bladder
Variable appearance
Associations
Epispadias
GU, pelvic, abdominal wall, spine, rectal anomalies
Overlap with cloacal extrophy (+ omphalocele + spine)

44. Other cases…SAME appearance….
Diagnosis?????
Bladder Exstrophy

45. Summary
Gastroschisis - Don’t mistake 1st trimester physiologic bowel herniation for gastroschisis
Look for signs that may lead to complex outcome
Intracorporeal (atresia?), Extracorporeal bowel dilation
Herniation of other viscera
Concomitant malformations
rarely involves the liver -- rule out omphalocele with ruptured membrane
Not usually chromosomal or syndromic
Omphalocele
Look for membrane, cord inserts on membrane
Often additional structural malformations
Considerable risk of chromosomal, syndromic diagnoses (BWS)
Amniotic bands
Look for additional places of involvement, extremities
Think of body stalk – short/absent cord, fixed
Exstrophy
No bladder, low CI, normal fluid, DSD

46. Thank you