The effect of pelvic ileal reservoir volume and antiperistaltic reflux on emptying efficiency

The emptying efficiency of four different designs of pelvic ileal reservoir was compared using two different techniques of measurement.

Thirty-four patients were studied one year after restorative proctocolectomy. In each the ileal reservoir was filled with methyl cellulose paste labeled with 51chromium-chromate and technetium Tc 99m-diethylenetriamine pentaacetic acid. Percentage evacuation was calculated from 1) the difference in 51chromium activity between the recovered effluent and the total paste administered and 2) gamma camera measurements of technetium Tc 99m-diethylenetriamine pentaacetic acid activity within the ileal reservoir before and after evacuation.

Median evacuation using the 51chromium method was 84, 90, 70, and 75 percent for the W40, W30, J40, and J30 reservoirs respectively. The results were not significantly different from those obtained using the gamma camera: 83, 87, 67, and 71 percent (P = not significant). Patients with either type of W reservoir evacuate isotope-labeled paste more efficiently than patients with J40 reservoirs (P < 0.05 and P < 0.001, respectively) but not J30 reservoirs (P = not significant). However, if the actual volume of paste evacuated during a visit to the lavatory is measured, it is greatest for J40 reservoirs (median, 300 ml compared with 258 ml for W40, 289 ml for W30, and 268 ml for J30; P = not significant).

Gamma camera measurement of ileal reservoir emptying is as accurate as our previous standard technique and provides a qualitative record of pouch evacuation, which may reveal reasons for inefficient emptying. The gamma camera images reveal that the difference in emptying percentage between W and J pouches is because of reflux of paste into the afferent ileum occurring more frequently in J pouches than in W pouches. The effect of this phenomenon on emptying is more than compensated for by the increase in reservoir capacity created by the reflux.