A 33 year old primigravid woman attended the Fetal Unit of our hospital at 21 weeks of gestation for prenatal examination. An ultrasound scan showed a single anechoic cystic mass measuring 3 cm in diameter (3 × 3 cm) in the abdomen of the fetus, with no dilatation of other parts of the intestine. At 25 weeks, an ultrasound scan showed distended bowel loops with decrease in size of the fluid-filled lesion seen on the first scan. At 32 weeks of gestation, the cystic mass could not be seen but the bowel distension had increased. Magnetic resonance imaging showed dilated fluid-filled intestinal loops (Fig. 1) and the site of intestinal atresia. The colon and the small intestine beyond the atresia were normal. At 35 weeks of gestation, an ultrasound scan showed a decrease in size of the dilated loops, moderate fetal ascites, absence of peristalsis and echogenic material outside the bowel. All these findings suggested intrauterine intestinal perforation. An elective caesarean section was performed at 35 weeks of gestation. A baby boy was born weighing 2800 g. He had abdominal distension and moderate scrotal swelling. The infant underwent a transverse laparotomy immediately after delivery. An ileal perforation was seen proximal to an atretic segment of bowel (ileal atresia type II) (Fig. 2). Meconium peritonitis was confirmed. The bowel walls showed mild inflammation without ischaemic changes consistent with a recent intestinal perforation. A primary ileostomy was performed with resection of 5 cm of distended ileum. His post-operative course was uneventful and intestinal continuity was restored by end-to-end anastomosis 14 days after the first surgical procedure. The baby started oral feeds seven days after the second operation. During this period, he received total parenteral nutrition. The boy is now 15 months old and has no problems.
Small bowel atresia is a rare congenital anomaly with an incidence of 1 in 3000 to 5000 live births1,2. Fetal bowel atresias may be detected antenatally by ultrasound on the basis of dilated bowel loops and occasionally, polyhydramnios3,4. The antenatal diagnosis of acute intestinal perforation in a previously detected ileal atresia has not so far been reported. Some authors described prenatal diagnosis of ileal atresia with subsequent perforation detected after birth5–7. Only one previous report of the antenatal diagnosis of bowel perforation in a fetus with gastroschisis has been found in the English literature8.
The prenatal diagnosis of fetal bowel obstruction has become more frequent with the widespread use of obstetric ultrasound. Congenital small bowel atresia typically produces distension of the proximal intestinal loops appearing in an ultrasound scan as multilocular fluid-filled sonolucent abdominal masses9. Other findings include increased peristalsis or particulate matter in the dilated bowel10.
In the last few years, ultrafast magnetic resonance imaging is a useful diagnostic method for antenatal evaluation of fetal anomalies11. We found only one previously reported case of antenatal ileal atresia with a precise location based on the findings of magnetic resonance imaging12.
The fetus with ileal atresia in our report had sudden changes in an ultrasound scan that suggested intestinal perforation as a result of massive dilatation of the bowel loops. Although the timing and the method of delivery are not usually influenced by the diagnosis of ileal atresia, there may be associated conditions that affect surgical treatment in the newborn, such as intestinal perforation. Immediate laparotomy before further bowel injury occurs might allow a better outcome. We feel that when acute bowel perforation is suspected based on the findings in an ultrasound scan, an urgent caesarean section should be performed2,8.