Detection of Upper Gastrointestinal Blood With Fecal Occult Blood Tests

Abstract

Objective Although fecal occult blood (FOB) tests have most often been used to detect occult bleeding from the lower gastrointestinal (GI) tract, their utility in detecting occult blood loss from the upper GI tract is less well understood. The aims of this study were to determine whether small amounts of blood from the upper GI tract can be detected by currently available FOB tests and, if so, to correlate FOB tests with semiquantitative GI blood. Methods Groups of 10 healthy volunteers without a history of GI disease drank 5, 10, or 20 ml of their own blood mixed with tomato juice for 5 or 3 consecutive days. Standard dietary and medication restrictions were observed. Consecutive stools were tested for 2 days before, as well as 4 days after, blood ingestion. Each stool was simultaneously tested for FOB with HemoQuant (HQ), Hemoccult II (HO II), Hemoccult II SENSA (SENSA), HemeSelect (HS), and FlexSure OBT (FS). Results The mean age and hemoglobin concentration of the study population were 29.3+/-0.5 yr and 14.3+/-0.3 g/dl, respectively. No subject noted GI symptoms during blood ingestion. Fecal blood levels (measured by HQ) were elevated within 2 days after initiation of blood ingestion and remained elevated until 2-3 days after cessation of blood ingestion. Mean fecal blood levels peaked at 2.1, 7.9, 8.0, and 13.5 (mg hemoglobin/g stool) in groups ingesting 5 ml/5 days, 10 ml/3 days, 10 ml/5 days, and 20 ml/3 days, respectively. The proportion of positive tests during and i…