The role of colonoscopy in young patients with rectal bleeding: a systematic review and meta-analysis.

Purpose: Anal bleeding is a frequent complaint in the coloproctological practice. Although usually associated with common anorectal disorders, it may represent a sign of an occult colorectal carcinoma. Our purpose was to evaluate the accuracy of the colonoscopy for detection of neoplastic lesions in patients under 50 years of age with rectal bleeding.

Methods: This systematic review and meta-analysis searched publications in PubMed, Web of Science, and Cochrane Library databases up to August, 2023. Cross-sectional and case-control studies including patients under 50 years with rectal bleeding evaluated by colonoscopy were included. Primary outcome was prevalence of neoplastic lesions (adenomas and adenocarcinomas). Secondary outcomes were prevalence of those lesions according to age and anatomic location. The study was registered on PROSPERO (CRD42021257859) on July 5, 2021.

Results: Nine studies comprising 4162 patients were analyzed. A total of 398 patients with adenomas and 40 patients with adenocarcinoma were identified. Prevalence of neoplastic lesions (adenomas and carcinomas) was 10%. In patients under 40 years, the prevalence of neoplastic lesions was 7% (6% of adenomas, 1% of carcinomas). Among patients aged 40-50 years the prevalence was 15%, 14%, and 1%, respectively. Most lesions (71%) were located distally to splenic flexure.

Conclusion: About 10% of patients under 50 years with anal bleeding will have a neoplastic lesion detected through colonoscopy. The greatest benefit of the procedure is observed between 40 and 50 years. Almost 30% of the neoplastic lesions were found in the proximal colon and could not be detected without the performance of a complete colonoscopy.