The Munich Polypectomy Study (MUPS): prospective analysis of complications and risk factors in 4000 colonic snare...

Screening colonoscopy with polypectomy has been shown to reduce the morbidity and mortality associated with colorectal cancer. However, there is a lack of large and systematic prospective studies of the complications of polypectomy.

Data on all snare polypectomies performed in 13 institutions (six hospitals and seven gastroenterology offices) were recorded prospectively during a 20-month period, including data on a 30-day follow-up period. The primary end points of the study were polypectomy complications, which were classed as "major" or "minor". Risk factors for complications were analyzed for both patient characteristics and polyp parameters.

A total of 3976 snare polypectomies in 2257 patients (mean age 64.5 years) were included in the study. The mean polyp size was 1.1 cm, and 72% were sessile. Complications occurred in 9.7% of patients (6.1% of polyps); 75% of these complications were minor; and the mortality rate was zero. Multivariate regression analysis revealed polyp size as the main risk factor, both for complications overall (odds ratio 6.56, 95%CI 4.45-9.67) and for major complications (odds ratio 31.01, 95%CI 7.53-128.1). Right-sided polyp location was a significant risk factor for major complications (odds ratio 2.40, 95%CI 1.34-4.28). Setting a cut-off value of 3% as an acceptable rate for major complications, polyps larger than 1 cm in the right colon or 2 cm in the left colon, and multiple polyps carried an increased risk.

Colonoscopic polypectomy is associated with a 10% rate of complications, but three-quarters of these are of minor clinical significance. More than 90% of the complications can be managed conservatively if adequate endoscopic expertise is available. Guidelines for intensified follow-up after polypectomy should be based on the size, location, and number of a patient's polyps.