A clinico-physiological comparison of ileal pouch-anal and straight ileoanal anastomoses.

The ileal pouch-anal anastomosis improves clinical results after colectomy and mucosal proctectomy compared to the straight ileoanal anastomosis. The question was what physiologic changes brought about by the pouch led to the improvement. Among 124 patients who had had ileoanal anastomosis, 25 volunteered for a detailed clinicophysiologic evaluation. Fourteen had had the ileal pouch-anal operation a mean of 8 months previously, and 11 had the straight ileoanal operation a mean of 25 months previously. Both groups of patients had satisfactory anal sphincter resting pressures (mean +/- SEM, pouch = 68 +/- 8 cm H2O, straight = 65 +/- 9 cm H2O, p greater than 0.05) and neorectal capacities (pouch = 278 +/- 26 ml, straight = 233 +/- 36 ml, p less than 0.05), and all could evacuate spontaneously. However, the pouch patients had a more distensible neorectum (delta V/delta P pouch = 9.5 +/- 1.3 ml/cm H2O, straight = 4.9 +/- 0.9 ml/cm H2O, p less than 0.05) and smaller amplitude neorectal contractions (pouch = 36 +/- 5 cm H2O, straight = 90 +/- 13 cm H2O; p less than 0.05). We concluded that the pouch-anal anastomosis increased the distensibility of the neorectum and decreased its propulsive drive, and so improved clinical results.