who underwent abdominal surgery (for the principal diagnosis of intestinovaginal fistula (ICD-9 code ***) to determine the surgical approach, type of resection, risk factors, and complications. 
A drawback of the ACS-NSQIP database is that only one diagnosis, the principal diagnosis is recorded, which inevitably results in underreporting of these fistulae. Also, we are not able to distinguish the underlying etiology of the fistulae.