Predictive value of a positive fecal occult blood test for upper gastrointestinal lesions in asymptomatic patients with a negative colonoscopy

Background: Colonoscopy is usually the initial diagnostic procedure performed in asymptomatic patients who are found to have a positive fecal occult blood test (FOBT) during colorectal cancer screening. When colonoscopy fails to identify a source of occult bleeding, the FOBT is labeled as false positive. In this patient population, the yield of upper endoscopy has not been well denned. Our purpose was to determine the predictive value of a positive FOBT for upper gastrointestinal lesions after a negative colonoscopy in a large group of asymptomatic patients. Methods: We reviewed the medical records of consecutive asymptomatic patients over the age of 50 years with a positive FOBT who were referred for an endoscopic evaluation from 1/92 to 1/97. FOBT was performed using Hemoccult test kits without rehydration. The diagnostic yield of upper endoscopy was determined and the data were stratified according to the presence or absence of anemia. Anemia was denned as a hemoglobin < 14 g/dL in males or < 12 g/dL in females. Results: 672 patients were evaluated by colonoscopy and 526 did not have a significant neoplasm identified (adenocarcinoma, adenoma ≥ 1 cm). Of these 526 patients, 498 (94.7%) were evaluated by EGD (272M; 226F; mean age 62.8 ± 0.4 years). A significant source of occult GI bleeding was found in 67 patients (13.5%). Etiology of Occult Bleeding Anemia (N=133) No Anemia (N=365) P Value Duodenal ulcer ≥ 1 cm (N=25) 14 (10.5%) 11 (3.0%) 0.0017 Gastric ulcer ≥ 1 cm (N=15) 9 (6.8%) 6 (1.6%) 0.006 Multiple vascular ectasias (N=9) 5 (3.8%) 4 (1.1%) 0.06 Gastric polyps ≥ 1 cm (N=7) 4 (3.0%) 3 (0.8%) 0.09 Severe erosive gastritis (N=4) 2 (1.5%) 2 (0.5%) 0.29 Gastric carcinoma (N=4) 3 (2.3%) 1 (0.3%) 0.06 Severe erosive duodenitis (N=2) 1 (0.8%) 1 (0.3%) 0.46 Esophageal carcinoma (N=1) 1 (0.8%) 0 (0.0%) 0.27 TOTAL (N=67) 39 (29.3%) 28 (7.7%) < 0.0001 Conclusions: Upper endoscopy yields important findings in asymptomatic patients with a positive FOBT after a negative Colonoscopy. The yield of upper endoscopy is significantly higher in anemic patients than in those in whom anemia is absent. In this patient population, evaluation of the upper gastrointestinal tract should be considered for all individuals, especially those in whom anemia is present.