Measurements of bile salt reflux are influenced by the method of collecting gastric juice.

Conventional gastric analysis by continuous aspiration and a marker technique that allows the stomach to retain its volume were compared with respect to the measured rates of gastric secretion and bile salt reflux in 10 fasting subjects. In marker technique studies, the stomach contained 35.7 +/- 3.3 ml (mean +/- SEM) and emptied at a rate of 4.1% +/- 0.4% per minute. Secretion rates of volume and acid were similar in studies using continuous aspiration and in marker technique studies. In contrast, the bile salt reflux rate was significantly higher when continuous aspiration was performed (0.89 +/- 0.11 vs. 0.38 +/- 0.06 mumol/min, p less than 0.01). Gastric bile salt concentrations were also higher (765 +/- 48 vs. 366 +/- 67 mumol/L, p less than 0.01). This may be due to changes in the gastroduodenal pressure gradient induced by evacuating the stomach. It is concluded that measurements of bile salt reflux are influenced by the method of collecting gastric juice.