Dr. Heyns - Flexible Sigmoidoscopy, Side effects and risks

Bloating and bowel distension are common due to the air inflated into the bowel. This usually lasts only 30 to 60 minutes. If biopsies are done or if a polyp is removed, there may be some spotting of blood. However, this is rarely serious. Other uncommon risks include a diagnostic error or oversight, or a tear (perforation) of the wall of the colon which might require surgery.