This is a rare condition in utero with an incidence of about 1 in 10,000. It is essentially vascular in origin and may arise from a volvulus, a transparietal constriction or a parietal perforation. A segment of bowel usually becomes atretic rather than stenotic. About a third of small bowel atresias involve the ileum. The risk of associated anomalies is low although Down syndrome has been reported.
The honeycomb appearances characteristic of small bowel distension may be the strongest clue. However it may be difficult, if not impossible, to distinguish small and large bowel distension even following birth. The absence of other anomalies and the presence of a normal amniotic fluid volume is important.
The multiple bowel loops need to be differentiated from renal tract obstruction. Under these circumstances the affected kidney will show pelvic dilatation and if both kidneys are affected it is likely that amniotic fluid volume will be decreased. Unilateral multicystic dysplastic kidneys will usually be restricted to one side of the abdomen and normal small bowel will be seen anteriorly.
Gross bowel distension with visible bowel contents
There may be multiple loops of bowel (honeycomb appearance)
Bowel peristalsis may be visible
- Diabetic embryopathy (including caudal regression/sirenomelia sequence)
- Fetal cocaine effects
- Multiple intestinal atresias
- OEIS complex
- Short-rib polydactyly type 1 (Saldino-Noonan)
- Trisomy 21
Filkins K, Russo J, Flowers WK Filkins K, Russo J, Flowers WK Third trimester ultrasound diagnosis of intestinal atresia following clinical evidence of polyhydramnios Prenat Diagn 5; 215-220
Kjoller M, Hom-Nielson G, Meiland H, Mauritzen K, Berget A, Hancke S Prenatal obstruction of the ileum Prenat Diagn 5; 427-430
Raman S, Chan LL, Chang KW, Rachagan SP Prenatal diagnosis of intestinal obstruction due to ileal atresia Med J Malaysia 47; 228-230