Risk factors for blood loss from adenomatous polyps of the large bowel: a colonoscopic evaluation with histopathological correlation.

In 27 patients with 74 colonic polyps we prospectively evaluated polyp-related risk factors and specific histopathological characteristics that might result in blood loss from these lesions. Each polyp was endoscopically bathed in saline which was then aspirated back into a syringe through a catheter and tested for presence of blood on a Hemoccult II slide. Forty-nine polyps were excised. We found the following: 1) A relatively small proportion of adenomas (approximately 11%) have a propensity to bleed. 2) Approximately 22% of polyp-bearing patients have a bleeding adenoma. 3) Risk factors for bleeding include polyp size greater than 1.0 cm, presence of a stalk, and cherry-red color; associated histopathological findings include marked vascular congestion and intramucosal lakes of blood. 4) Clinically detectable bleeding occurs after intramucosal hemorrhage in the polyp head and dissection of blood into the bowel lumen through the glandular or surface epithelium. Most polyps are small, sessile and pink, without histopathological features of hemorrhage and are unlikely to bleed. Therefore, patients with Hemoccult-positive stools in whom such neoplasms are found should undergo further study to detect other causes of gastrointestinal blood loss. High-risk polyps in otherwise asymptomatic patients can be held responsible for bleeding; in them colonoscopic polypectomy with follow-up Hemoccult testing is sufficient management. Only if bleeding persists is study of other parts of the gut essential.