Introduction: Given the high incidence of colorectal cancer in people aged 50 and older, colonoscopy is strongly recommended for individuals in this age group who experience hematochezia. We aimed to determine, in light of the increasing cases of cancer among young adults, whether the indication for colonoscopy is warranted in individuals under 40 who present with hematochezia.

Methods: We conducted a retrospective, observational study involving patients aged 18 to 39 who underwent colonoscopy between January 1, 2020, and December 31, 2024 across three gastrointestinal endoscopy centers in Brazzaville. Patients were categorized into two groups: those who underwent colonoscopy for hematochezia (Group 1) and those who underwent colonoscopy for other indications (Group 2). In both groups, we assessed sociodemographic characteristics, the frequencies and location of cancers and polyps. Additionally, we evaluated the frequencies of other causes of hematochezia in Group 1. Fisher’s exact test was used to compare the frequencies of selected lesions between the two groups.

Results: During the study period, 352 patients aged 18 to 39 years underwent total colonoscopy, including 80 for hematochezia (Group 1) and 272 for other indications (Group 2). In Group 1, the mean age was 31.5 ± 5.1 years, with 56% of patients being male. Hemorrhoids were the most prevalent cause of hematochezia. In Group 2, the mean age was 32 ± 5.6 years, with males constituting the 55.2% of the cohort. There prevalence of colorectal cancer was 10% in Group 1 and 4% in Group 2 (p=0.058). Cancers were predominantly located in the distal colon for both groups. The prevalence of polyps in Groups 1 and 2 was 5% and 2.5%, respectively.

Conclusion: The prevalence of colorectal cancer was higher among patients who underwent colonoscopy for rectal bleeding compare to those with other indications. Although the majority of cancers were located in the distal colon, the presence—albeit rare—of cancer localized to the right side highlights the necessity of performing complete colonoscopies in order to avoid missing proximal malignancies.