Diagnostic yield of colonoscopy in patients with melena and normal upper gastrointestinal endoscopy

Aims Melena, the passage of black, foul-smelling digested blood per rectum, typically signals an upper GI bleed originating proximal to the right colon. While EGD is the first-line diagnostic tool, a normal result often necessitates further endoscopic evaluation, especially total colonoscopy, to identify lower GI sources. This study aims to determine the diagnostic yield of colonoscopy in cases of melena with unremarkable EGD findings and to identify factors associated with these findings.

Methods This is a retrospective descriptive and analytical study conducted between January 2022 and November 2024, including 262 patients who underwent colonoscopy for melena with normal esophagogastroduodenoscopy. Data collection and statistical analysis were performed using SPSS 26. Patients with known inflammatory bowel disease (IBD) were excluded from our study based on these criteria.

Results The mean age of the patients was 66.6±12.5 years, ranging from 27 to 88 years. The cohort comprised 172 (65.5%) men and 90 (34.4%) women, with a sex ratio M/F=1.9. Four patients reported a family history of colorectal cancer, and six patients (2.3%) had a personal history of operated colorectal cancer. Melena was the sole presenting symptom in 38.2% of cases, while it was associated with iron deficiency anemia in 51.9%, constipation in 11.5%, general health decline in 9,5%, and abdominal pain in 6.1%. Colonoscopy was strictly normal in 34.4% of cases (n=90), whereas abnormal findings included colonic angiodysplasia in 16.8% (n=44), colonic diverticulosis in 16% (n=42), colorectal polyps in 13.7% (n=36), and colorectal cancer in 11.5% (n=30). Age was the only factor significantly associated with abnormal colonoscopy findings in cases of melena (p=0.033).

Conclusions Colonoscopy has a substantial diagnostic yield in patients presenting with melena and normal EGD, identifying significant lesions such as angiodysplasia, diverticulosis, and colorectal cancer. Age was a key factor associated with abnormal findings, highlighting the importance of thorough evaluation in older patients.

Publication History

Article published online:
27 March 2025