You can’t have a colonoscopy with aspirin, and it’s best to stop taking this medication 3 to 7 days before your colonoscopy. Aspirin inhibits platelet aggregation and can stop blood clots from forming. If a patient takes aspirin and bleeding occurs during a colonoscopy, it may cause platelets to fail to aggregate and increased bleeding may occur. If a lesion is found during a colonoscopy it is also not possible to biopsy it and there is a risk of intestinal bleeding. Enteroscopy is an important modality for diagnosing intestinal diseases, enabling observation of the intestinal mucosa and pathologic biopsy of lesions. Patients need to stop taking aspirin for 3 to 7 days as prescribed by their doctor before undergoing colonoscopy.