Prediction of incontinence following low anterior resection for rectal carcinoma

This study was performed to predict incontinence following low anterior resection for rectal cancer.

Preoperatively, 21 patients were evaluated via patient history and a physical examination that included anal manometric studies. Six months postoperatively, repeat manometric studies and clinical evaluations were performed to assess the level of continence. Degree of continence was graded based on severity of the dysfunction and grade of the continence score.

The formula used for predicted postoperative resting pressure is as follows: predicted postoperative resting pressure = 0.42 x preoperative resting pressure +1.56 x length of remaining rectum +12.37 (R2 = 0.58; P < 0.001). It was demonstrated that patients with low predicted postoperative resting pressures (< 30 mmHg) had incontinence, and those with high predicted postoperative resting pressures (> 35 mmHg) were continent. There were significant correlations between length of the remaining rectum and ratio of the decrease in maximum resting pressure (postoperative/preoperative maximum resting pressure; r = 0.63; P < 0.01).

Continence following low anterior resection may be influenced by maximum resting pressure function of the internal anal sphincter; if it is injured during surgery, incontinence will occur. We may be able to foretell incontinence by using the predicted postoperative resting pressure formula, which is calculated by using preoperative resting pressure measurements and then determining the length of the remaining rectum.