Use and abuse of faecal occult blood tests in an acute hospital inpatient setting

The role of the faecal occult blood test (FOBT) is untested. The aims of this study were to define the use of FOBT in a general hospital setting and to determine its influence on patient management.

Case notes and laboratory reports were retrospectively reviewed in all FOBTs performed in 2006 across three acute hospitals, with specific reference to clinical setting, indication, influence over clinical decision-making and management. Both guaiac and immunological tests were performed on all specimens.

A total of 330 patients aged 2-104 (mean 74) years, 47% men, had 461 tests performed. A positive result was recorded in one or both tests in 64% of patients. Evidence of dietary restriction was found in only eight (2%) of patients and 218 (66%) patients took one or more medications that could have caused a false positive result. Indications were mostly for overt or suspected gastrointestinal blood loss with or without anaemia and/or iron deficiency, but 5% were for non-bloody diarrhoea and 3% screening for colorectal cancer. Patient care was adversely affected or delayed in 54 patients (16%), mostly because of the result being the stimulus for the decision to refer or not for endoscopy. Only one was considered appropriate as a screening test for colorectal cancer.

The FOBT was applied in clinically inappropriate settings without consideration to confounding issues, and often led to inappropriate clinical decisions with considerable cost to hospital and patient. There is no place for FOBT in an acute hospital setting.