Scintigraphic Assessment of the Anorectal Angle in Health and After Ileal Pouch-Anal Anastomosis

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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° SD) and anopouch angle in patients (108 ± 19°) were similar (p = 0.3). Sitting straightened the angle in both groups (p < 0.03), whereas sphincteric squeeze and a Valsalva maneuver sharpened the angle in both the sitting and standing positions (p < 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 < 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.