Duodenal obstruction due to windsock deformity in a 13 year old female

A 13 year old presented with epigastric distension and pain, with bilious  vomiting of 1 week duration. There was no history of dyspepsia but patient was constipated. Plain abdominal radiograph reveal a grossly dilated stomach and first part of duodenum. However, a barium meal showed the dilatation progressing to the third part of the duodenum with trickling of contrast into the collapse fourth part of the duodenum near the ligament of Treizt.   Duodenotomy at laparotomy confirmed a membrane causing windsock  deformity in the duodenum which was excised and patient has since been well. This is a delayed and rare presentation of this anomaly which call for a consideration among causes of upper gastrointestinal obstruction.