Pelvic pouch emptying scan: an evaluation of scintigraphic assessment of the neorectum

Although scintigraphic pelvic pouch emptying scans have been used to evaluate neorectal function in patients who have undergone colectomy, mucosal proctectomy, and ileoanal pouch anastomosis, previous reports have not documented the reliability of this test in measuring pouch volume and emptying. Thus, this study was undertaken to determine: (1) the reliability of this test in patients with stable functional results and, (2) whether the emptying fraction correlates with the volume of the pouch. Ten patients who had stable functional results had 99m Tc-sulphur colloid pouch emptying scans performed on two occasions, one week apart. The average volume of artificial stool that was instilled was 338±104 cc. The mean difference in the volume instilled between the initial and repeat scans was 78±26 cc and the mean absolute difference in the percentage evacuated was 12±9 percent. These inter-test differences were not statistically significant (p>0.05). There was no correlation between the volume of artificial stool instilled into the pelvic pouch and the fraction spontaneously emptied (r=-0.1). Our results suggest that the 99m Tc-sulphur colloid pelvic pouch emptying scan is reliable in patients with stable functional results. Pouch emptying fraction is independent of pouch volume.