Visualization of a Y-configuration and peristalsis on prenatal sonography: The pathognomonic sign of an ileal duplication cyst

Objective: Enteric duplication cysts are a rare congenital malformation that consists of a cystic formation adjacent to the native gastrointestinal tract. A double wall appearance on fetal abdominal sonography is highly suggestive of its diagnosis. However, this sign also can be seen in an ovarian cyst, a mesenteric cyst, and a Meckel's diverticulum. To the best of our knowledge, this case is the first report of accurate prenatal diagnosis based upon the presence of a Y-configuration and peristalsis on prenatal sonography. We herein present prenatal and postnatal images including ultrasonogram and discuss the differential sonographic findings of an intra-abdominal cystic mass. Case report: A 28-year-old pregnant woman, gravida 1, para 1, was referred to our hospital at 29 + 3 weeks' gestation for the evaluation of a fetal intra-abdominal cystic mass. On an ultrasound examination, a thick-walled, unilocular cystic mass, measuring 1.42 × 0.93 cm in diameter was detected. A double-layered wall was seen on the bottom line of the cystic mass. A serial ultrasound examination showed the enlargement of the cystic mass with advancing pregnancy. In addition to the multilayered wall, a Y-configuration was demonstrated in the sharing muscular wall, and real time peristaltic movements were visualized at 39 + 3 weeks’ gestation. With all these findings taken together, we made a diagnosis of an enteric duplication cyst with confidence. Conclusion: Prenatal sonography alone can be used for the accurate diagnosis of an ileal duplication cyst, allowing a laparoscopic-assisted surgical treatment following birth before the onset of symptoms or complications.