Fecal short-chain fatty acid concentrations and effect on ileal pouch function

Random stool samples were obtained from 14 ileal pouch-anal anastomosis (IPAA) patients 43 +/- 5 (mean +/- SEM) months after surgery, and the concentrations of individual short-chain fatty acids (SCFAs) were determined by gas liquid chromatography. Stool frequency was determined from a diary recorded for 15 days prior to stool sampling. The frequency, amplitude, and duration of phasic contractions (PCs) within the pouch following infusion of a physiologic concentration of SCFAs and normal saline randomly into the pouch of six IPAA patients were determined manometrically. The mean total SCFA concentration after IPAA did not differ significantly from normal stools (83 +/- 20 mM after IPAA vs. 97 +/- 10 mM for controls; P > 0.05). In the IPAA patients, regression analysis demonstrated an inverse relationship between stools per day and total SCFA concentration (r = 0.73; P < 0.001). Moreover, no change in frequency (3.0 +/- 0.9 vs. 3.2 +/- 0.8 PCs/30 minutes), amplitude (26 +/- 5 vs. 25 +/- 4 mmHg), or duration (23 +/- 3 vs. 26 +/- 2 seconds) of PCs was found after SCFA infusion compared with saline control (P > 0.1). These findings demonstrate that SCFAs are present in ileal pouch effluent and that stool frequency may be related to fecal SCFA concentration. Also, the normal contractile response of the terminal ileum to SCFAs does not occur in the ileal pouch.