Abdominal Wall Defect
Paula J. Woodward, MD
DIFFERENTIAL DIAGNOSIS
Common
Gastroschisis
Omphalocele
Physiologic Gut Herniation (Mimic)
Less Common
Amniotic Band Syndrome
Body Stalk Anomaly
Rare but Important
Bladder Exstrophy
Cloacal Exstrophy
Pentalogy of Cantrell
OEIS Syndrome
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
Must document normal abdominal wall surrounding cord insertion in every case
Umbilical cord insertion site key for making diagnosis
Gastroschisis: Defect to right of normal cord insertion
Omphalocele: Cord inserts on membrane surrounding defect
Bladder and cloacal exstrophy: Low defect below cord insertion
Cord insertion may be involved with cloacal extrophy
Pentalogy of Cantrell: High defect above and potentially involving the cord insertion
Amniotic band syndrome: No defined anatomic distribution
Helpful Clues for Common Diagnoses
Gastroschisis
Bowel herniation through a right paramedian abdominal wall defect
Color Doppler shows umbilical cord insertion in normal location
No covering membrane
Small bowel always herniates through defect
Large bowel and stomach also reported
If liver or other solid organs are seen, gastroschisis unlikely (consider ruptured omphalocele, amniotics bands, body stalk, pentalogy of Cantrell)
Variable appearance of bowel
Both intra- and extra-abdominal loops may be dilated
Bowel wall may become thickened, echogenic, matted, and nodular from fibrinous peel on exposed bowel
Omphalocele
Midline abdominal wall defect with herniation of abdominal contents into base of umbilical cord
Smooth mass protruding from central anterior abdominal wall with covering membrane
Umbilical cord inserts onto membrane
Usually centrally but may be eccentric
Liver and small bowel most common contents
Associated structural abnormalities are common
Omphaloceles containing small bowel have higher association of both chromosomal and structural malformations
Cardiac and gastrointestinal malformations are most common
Aneuploidy in 30-40%: Trisomy 18 most common
Also associated with syndromes including Beckwith-Wiedemann (omphalocele, organomegaly, macroglossia)
Physiologic Gut Herniation (Mimic)
Be careful diagnosing an abdominal wall defect before 12 weeks
Bowel does not return to abdomen until 11.2 weeks
Normal bowel herniation should not extend more than 1 cm into cord
Never contains liver
Helpful Clues for Less Common Diagnoses
Amniotic Band Syndrome
“Slash” defects that do not conform to developmental malformations
Asymmetric distribution of defects is hallmark of syndrome
Often involves multiple parts of the body
Defects may be isolated or multiple, but not in specific pattern
Craniofacial deformities are common and often severe
Bands in amniotic fluid appear as multiple thin membranes
Bands are often tightly adherent to fetus and may not be visible
Body Stalk Anomaly
Lethal malformation characterized by attachment of visceral organs to the placenta
Short or absent umbilical cord
Vessels seen running from placental surface to fetal torso
No free floating cord identified
Gross distortion, with loss of anatomic landmarks
Scoliosis prominent feature
May have multiple acute angulation points
Helpful Clues for Rare Diagnoses
Bladder Exstrophy
Failure of lower abdominal wall closure resulting in exposed bladder
Variable severity
Mild form associated with exstrophy of urethra and external sphincter
Severe form associated with wide diastasis of symphysis pubis and genital defects
Absence of bladder on prenatal ultrasound
Soft tissue mass on lower anterior abdominal wall, below cord insertion
Mass is posterior bladder wall
No extruded abdominal contents as in other abdominal wall defects
Beware of misdiagnosis in cases of a normal but empty bladder
Rescan after an interval of 10-15 minutes
Cloacal Exstrophy
Spectrum of abnormalities resulting from abnormal development of cloacal membrane
Absence of normal bladder
Lower abdominal wall defect
Herniation of bowel between 2 halves of a split bladder
Appearance of prolapsed ileum described as looking like an elephant’s trunk
Omphalocele forms upper part of defect
Males may have bifid scrotum and penis
Associated anomalies very common
Vertebral, myelomeningocele, urinary tract, gastrointestinal, clubfeet
Pentalogy of Cantrell
Complex malformation with 5 components
Anterior diaphragmatic hernia
Midline abdominal wall defect
Cardiac anomalies
Defect of diaphragmatic pericardium
Lower sternal defect
Most likely diagnosis when there is a high omphalocele associated with ectopia cordis
OEIS Syndrome
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