Evolution of sonographic findings in a fetus with ileal atresia.

We report a case of a meconium pseudocyst secondary to ileal atresia and midgut volvulus. Initially, a single anechoic cyst was detected on prenatal sonography. The cyst gradually increased in size during the second trimester and eventually appeared as a large mass in the lower abdomen with echogenic content and associated with bowel dilatation. This case indicates that until the mid third trimester a single sonolucent cyst without signs of bowel obstruction may be associated with congenital intestinal obstruction.