Takeshi Mouri, Teruyoshi Amagai, Hajime Kawakami, Masayuki Murofushi

Department of Pediatric Surgery, Ibaraki Children’s Hospital

　　A girl with body weight 3080g was delivered vaginally. At 25 weeks gestational age, unilocular cystic lesion of right lower abdomen had been detected by fetal ultrasonography (US). Her right abdomen bulged on the second day of life, and she started to vomit on the fifth day. She was diagnosed with ovarian cyst tentatively by plain abdominal X-ray, US and CT scan. On the tenth day, air influx and air-fluid level, which was shown inside of the cyst by plain abdominal X-ray and CT scan, led to a diagnosis of duplication of the small intestine. A laparotomy was undertaken on the 11th day of her life and revealed that she had a duplication cyst of the ileum with a communication noted between the cyst and ileum.
　　It was conceivable that mucus had pooled in the duplication cyst during her embryonal period, after which the liquid was replaced by air from the ileum through the conduit after birth.

Keywords：Duplication of alimentary tract, Fetal ultrasound, Newborn, Air-fluid level