Determinants of optimal results after ileoanal anastomosis: Anal proximity and motility patterns of the ileal reservoir

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Abstract
End results after ileoanal anastomosis with a proximal ileal reservoir range from defecatory frequency to obstruction. To define the physiological (reservoir compliance, motility) and anatomical (reservoir design, anal proximity) determinants of the varying clinical outcome, we placed an S‐shaped (SS‐R) or double‐barreled (DB‐R) reservoir in comtinuity with the anus in dogs, either directly or via 2‐cm or 6‐cm ileal conduits.Because of increased compliance, either reservoir provides for fecal storage, prolongs intestinal transit time, and alleviates the defecatory frequency seen after direct ileoanal anastomosis. Electromyography and manometry revealed that repetitive, simultaneous peristaltic contractions of the 2 and 3 ileal limbs forming the DB‐R and SS‐R, respectively, are required to generate the intraluminal pressure waves necesssary to promote complete reservoir evacuation. Such simultaneous contractions occur less often in the SS‐R than in the DB‐R. Therefore, the SS‐R develops into an inert, obstructing viscus within 6 months, which is not seen with the peristaltically stronger DB‐R. Ileal conduits facilitate reservoir placement; but, when longer than 2 cm, they impede reservoir evacuation and predispose to obstruction.We conclude that, in contrast to the SS‐R, the DB‐R has physiological characteristics (compliance yet contractility) that allow normal bowel habits, but only if it is placed in anatomical proximity to the anus.