NEW YORK (Reuters Health) – Polyps located in the right hemi-colon, particularly in the cecum, seem to be a substantial and independent risk factor for delayed post-polypectomy hemorrhage, clinicians from the Netherlands report.

“A low threshold for preventive hemostatic measures” is advised when removing right-sided polyps, conclude Dr. K. Tim Buddingh from University Medical Center Groningen and colleagues in the January 25 advance online issue of the American Journal of Gastroenterology.

Delayed bleeding occurring several days after a seemingly uneventful colonoscopic polypectomy is “rare but can be severe and life-threatening,” the study team notes in an e-mail to Reuters Health. In three studies, delayed post-polypectomy hemorrhage occurred in 0.3% to 0.6% of polypectomies.

Large polyp size is the only polyp-related factor that has been unequivocally proven to raise the risk of delayed bleeding. The literature regarding polyp location as a risk factor is less certain.

Three studies hinted at a higher risk of delayed bleeding with right-sided polypectomies, but the results were not statistically significant. A fourth study found more major complications resulting from right-side polypectomy, but no distinction was made between the type of complication (perforation or hemorrhage) and the timing of the complication (immediate or delayed). In a fifth study of 37 cases of delayed post-polypectomy hemorrhage, polyps were distributed equally in the right and left colon.

To investigate further, Dr. Buddingh and colleagues conducted a multicenter retrospective case-control study. They identified 39 case patients who had overt bleeding starting at least one hour after the colonoscope was retracted from the rectum. For every case patient, they selected three controls (n = 117) who underwent uneventful polypectomy at the same center within the same time frame.

In multivariate analysis, large polyp size and right-sided location were both independent risk factors for delayed hemorrhage, the researchers report.

For every 1 millimeter increase in polyp diameter, the risk increased by 13% (odds ratio 1.13; P < 0.001). The risk of delayed hemorrhage was more than fourfold higher for polyps located in the right hemi-colon (odds ratio, 4.67; P = 0.001). “We suspected that delayed bleeding may occur especially after removal of polyps located in the right side of the large bowel,” the study team told Reuters Health. “This possibility had been suggested by others but had never been investigated thoroughly. Our suspicion was confirmed that bleeding occurred more frequently after removing polyps from the right side of the large bowel.” Polyps in the cecum (the area where the small bowel enters the large bowel) seemed to be especially at high risk; the odds ratio in univariate analysis 13.82. But this could not be assessed in multivariate analysis as the number of cases was too small, the researchers note. The type of polyp (sessile or pedunculated) did not appear to influence risk of delayed bleeding after polypectomy. “Surprisingly,” the researchers say, female gender emerged as an independent risk factor for delayed hemorrhage (odds ratio, 2.85; P = 0.024). They emphasize, however, that they did not correct for other patient-related risk factors such as comorbidity. “As such, this study cannot, and did not aim to, assess patient-related risk factors.” Strengths of the study, the researchers say, include the large control group, which helps reduce the influence of unrecognized confounders. “This has not been done in the other studies on this subject,” they note. They also say it’s unlikely that anticoagulant medication had a large role in the occurrence of delayed bleeding given that only a few patients used anticoagulant medication and these were fairly evenly distributed among patients with right-sided and left-sided polyps. Based on their findings, Dr. Buddingh and colleagues advise clinicians to be “extra prudent and liberally apply preventive hemostatic measures” when removing right-sided polyps, “even when no bleeding occurs during the procedure itself.” Reference:
Location in the Right Hemi-Colon Is an Independent Risk Factor for Delayed Post-Polypectomy Hemorrhage: A Multi-Center Case–Control Study


Am J Gastroenterol 2011. Published online January 25, 2011.