Inflammatory bowel disease symptoms at the time of anal fistula lead to the diagnosis of Crohn's disease

•What is already known on this subject? Perianal lesions can precede the diagnosis of Crohn's disease.•What are the new findings? A medical history of anal fistula surgery resulted in the diagnosis of CD in 7% of cases.•How might it impact on clinical practice in the foreseeable future? Weight loss and the presence of digestive symptoms should be investigated at the time of anal fistula to diagnose CD to select patients requiring endoscopic exploration after anal fistula and should guide the surgeon towards a sphincter-saving strategy. Most anal fistulas are crypto-glandular. Nevertheless, anal fistulas can reveal Crohn's disease (CD). The aim of our study was to evaluate the risk of developing CD in patients undergoing surgery for anal fistula. All patients undergoing surgery for anal fistula in our center between January 1, 2008 and January 31, 2017 were identified through a prospective administrative database. Demographic, clinical, and laboratory data were retrospectively collected. Ninety-three patients underwent anal exploration under general anesthesia. The median age at diagnosis of fistula was 43 years (IQR, 34-56) and 27% (n=29) were women. Twenty-seven percent (n=16) had had at least one previous fistula episode. After a median follow-up of 16.8 months (IQR, 7.2–42.0), seven (7.4%) patients were diagnosed with CD. The median time between the diagnosis of fistula and that of CD was 7.6 months (IQR, 2.7, 26.1). Chronic diarrhea (P=0.0003), weight loss (P=0.001), and chronic abdominal pain (P=0.002) were associated with the diagnosis of CD. Characteristics of the fistulas (number, simple/complex, abscess), smoking, extra-digestive manifestations of CD, or a family history of IBD were not associated with the diagnosis of CD. A medical history of anal fistula surgery resulted in the diagnosis of CD in 7% of cases. Weight loss and the presence of digestive symptoms were associated with the diagnosis of CD. These elements could be used to select patients requiring endoscopic exploration after anal fistula.