Risks of intestinal anastomoses in Crohn's disease. Six hundred fifty-eight intestinal anastomoses in 429 operations for Crohn's disease were studied prospectively during an 8-year period to detect variables connected with perioperative morbidity. Postoperative complications occurred in 9.7% of the patients, 4% had to be reoperated on, and the overall mortality rate was 0.5%. In multivariate analysis by stepwise logistic regression, the only variable significantly (p = 0.03) associated with overall rate of complications was long-term corticosteroid therapy. Serious complications were more common in cases of intra-abdominal abscesses (p = 0.01) and preoperative steroid medication (p = 0.03). The combination of both of these risk factors increased the rate of reoperations from 0.6% (no steroids, no abscess) to 16% (steroids and abscess). No significant association with postoperative complications could be found for age, sex, duration of disease, previous operations, nutritional status, emergency surgery, extent of disease, type, number, and localization of anastomoses, presence of proximal ileo-/colostomy, or histologically inflamed margins of resection. 