Scintigraphic assessment of the anorectal angle in health and after ileal pouch-anal anastomosis

Abstract

To determine whether the anorectal angle was preserved after ileal pouch-anal anastomosis, a simple, safe, low-radiation, real-time method of imaging the anorectum was developed. A cylindrical balloon was placed in the neorectum and anal canal and filled with a solution of 99mTc in water. A gamma camera then imaged the angulation of the balloon while the subject was at rest, during sphincteric squeeze, and during a Valsalva maneuver. Thirteen healthy volunteers and six patients were studied after ileal pouch-anal anastomosis. An angle was identified in all controls and patients. In the lateral decubitus position at rest, the mean anorectal angle in controls (102 +/- 18 degrees; SD) and anopouch angle in patients (108 +/- 19 degrees) were similar (p = 0.3). Sitting straightened the angle in both groups (p less than 0.03), whereas sphincteric squeeze and a Valsalva maneuver sharpened the angle in both the sitting and standing positions (p less than 0.03). In the lateral decubitus position, however, the pouch group was less able to sharpen the angle than were the controls (p = 0.04). In controls, the anorectal junction descended during sitting and elevated during squeeze (p less than 0.03), but this did not occur in the pouch group. In conclusion, maneuvers favoring or stressing continence (squeeze, Valsalva) sharpened the anorectal angle and elevated the pelvic floor, whereas a maneuver favoring defecation (sitting) straightened the angle and caused the pelvic floor to descend. After ileal-anal anastomosis, the angle and its movements (except those while lying) were similar to controls. Elevation of the pelvic floor during squeeze, however, was decreased, indicating a decreased mobility of the pelvic floor after operation.