Introduction Diagnosing and treating patients with chronic watery diarrhoea is a common clinical problem. Despite the accuracy and the availability of the SeHCAT (75 Selenium HomotauorCholic Acid Test), bile salt malabsorption remains an under recognised cause of chronic watery diarrhoea. We aimed to determine which clinical features and laboratory investigations would increase the likelihood of finding bile salt malabsorption as demonstrated by a positive SeHCAT test (retention <10% at 7 days).

Methods A retrospective analysis was undertaken of patient's records for all patients who underwent a SeHCAT scan in an 8-year period between 2001 and 2009 in a tertiary Gastroenterology Department (Group 1 n=316). Patient demographics, symptoms, previous medical and surgical history, as well as laboratory investigations (including full blood count, serum folate, vitamin b12, ferritin and albumin) were analysed. Statistical analysis was performed using SPSS (V.17.0 for windows) with chi squared analysis used to compare the data. Concurrently a previously assessed cohort of patients with irritable bowel syndrome was examined to determine the potential utility of SeHCAT scanning (Group 2 n=314).

Results Out of the 316 patients (Group 1) who underwent a SeHCAT, 273 patient records were located and analysed (191 female, 82 male; median age 49). 107 patients (39.2%) had a positive result. The mean time from first hospital visit to SeHCAT result was 30 weeks. Patient characteristics predictive of a positive SeHCAT were: terminal ileal Crohn's (p<0.01), terminal ileal resection (p<0.01), inflammatory bowel disease (p<0.01), previous small bowel surgery (p<0.01) and previous cholecystectomy (p<0.01). 36 of the 107 patients (36.4%) who had a positive SeHCAT also had ROME 3 criteria for irritable bowel syndrome. In the IBS control cohort (Group 2) only 6/314 (1.9%) patients had undergone a SeHCAT scan (p<0.001 compared to current group) meaning that potentially 114 patients with bile salt malabsorption could have been missed.

Conclusion Bile Salt Malabsorption is common and should be considered earlier in patients with predisposing factors (including inflammatory bowel disease, terminal ileal disease, previous small bowel surgery and post cholecystectomy). Consideration should also be given for bile salt malabsorption prior to the diagnosis of diarrhoea-predominant irritable bowel syndrome.