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

PURPOSE: The emptying efficiency of four different designs of pelvic ileal reservoir was compared using two different techniques of measurement. METHO D: Thirty-four patients were studied one year after restorative proctocolec tomy. In each the ileal reservoir was filled with methyl cellulose paste la beled with (51)chromium-chromate and technetium Tc 99m-diethylenetriamine p entaacetic acid. Percentage evacuation was calculated from 1) the differenc e in (51)chromium activity between the recovered effluent and the total pas te administered and 2) gamma camera measurements of technetium Tc 99m-dieth ylenetriamine pentaacetic acid activity within the ileal reservoir before a nd after evacuation. RESULTS: Median evacuation using the (51)chromium meth od was 84, 90, 70, and 75 percent for the W40, W30, J40, and J30 reservoirs respectively. The results were not significantly different from those obta ined using the gamma camera: 83, 87, 67, and 71 percent (P = not significan t). 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 t he actual volume of paste evacuated during a visit to the lavatory is measu red, 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). CONCLUS IONS: Gamma camera measurement of ileal reservoir emptying is as accurate a s our previous standard technique and provides a qualitative record of pouc h evacuation, which may reveal reasons for inefficient emptying. The gamma camera images reveal that the difference in emptying percentage between W a nd J pouches is because of reflux of paste into the afferent ileum occurrin g more frequently in J pouches than in W pouches. The effect of this phenom enon on emptying is more than compensated for by the increase in reservoir capacity created by the reflux.