Estimation of small bowel transit time following colectomy and ileal reservoir construction

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Abstract
A study was carried out to evaluate the breath hydrogen test as a method of estimating small bowel transit in patients with an ileal pouch and to determine whether gut transit time influenced functional outcome. Twelve patients with an ileal reservoir and ten control subjects ingested a test meal of 400 ml chicken soup, 20 g lactulose and 50 ml dilute barium solution. Concurrent breath hydrogen testing and radiological screening was carried out until the head of the test meal reached the ileal pouch or caecum. At the time that the test meal arrived in the pouch, faecal anaerobic bacterial counts were obtained. Pouch compliance, functional capacity and anal sphincter pressures were also measured. While there was an excellent correlation between radiological and breath hydrogen measures of orocaecal transit time in controls (P < 0.001), no such relationship was found for oropouch transit. Four of the 12 patients with a pouch produced no hydrogen after test meal ingestion, while in two other such patients breath hydrogen peaks occurred when the head of the meal was in the jejunum. The magnitude of the breath hydrogen rise in patients with an ileal pouch correlated well with faecal anaerobic bacterial counts (P < 0.01). The median (95 per cent confidence interval) radiological small bowel transit time was more rapid in patients with a pouch than in control subjects: 28 (23–33) versus 72 (46–86) min (P < 0.01). Increased 24‐h frequency of defaecation was associated with more rapid small bowel transit after ileal reservoir construction (P < 0.01) but correlated with neither pouch capacity nor compliance. These data show that small bowel transit time may be a determinant of ileal pouch function but that breath hydrogen estimation of gut transit time in patients with an ileal reservoir is unreliable.