Introduction Bile acid malabsorption (BAM) is a potentially under-recognised cause of chronic diarrhoea. An accurate diagnostic technology exists in the form of the SeHCAT (⁷⁵Se—homotaurocholate) test. The British Society of Gastroenterology investigation algorithm places SeHCAT as a very late stage investigation, but if BAM is common or SeHCAT unavailable it may easily be overlooked. This is a treatable condition: the response to bile sequestrants as an empirical “investigation” is not an adequate approach. This study aimed to characterise the results of SeHCAT in a large cohort of patients, and also to determine how well adhered to were the British Society of Gastroenterology guidelines for the investigation of chronic diarrhoea.

Methods The electronic records of 276 patients who underwent SeHCAT scanning between 2005 and 2011 were retrospectively analysed as a medical student project.

Results Bile acid malabsorption (BAM) was very common in patients who underwent SeHCAT testing, found in 110 (40%) of the 276 patients. In the overall cohort, 136 patients had no prior underlying disease or surgery recorded that might cause diarrhoea, and 86 of these displayed no abnormalities on full screening including endoscopies and coeliac tests. Of the 110 with BAM, 28 had undergone neither endoscopy nor coeliac screening. Predictably, 22 of the 26 (85%) Crohn's patients with a history of ileal resection had positive results, as did 15 of the 21 (71%) ileally resected patients who did not have Crohn's disease. Sixteen patients (55%) with post-cholecystectomy diarrhoea showed evidence of BAM.

Conclusion BAM is common in subjects undergoing SeHCAT. The current guidelines should be revised to take into account BAM as an important and common cause of diarrhoea, with SeHCAT earlier in the process. It is apparent that clinicians are not widely using the BSG algorithm, presumably using clinical judgement in patients in whom BAM seems likely, and, for example, opting not to undertake colonoscopy in many cases. In the absence of a terminal ileum, the BAM diagnosis is almost universal and the test is probably superfluous. A broader and contemporary health technology assessment including all patients currently investigated for chronic diarrhoea is now required in order to define a new algorithm.

Competing interests None declared.