Anorectal function after restorative proctocolectomy and low anterior resection with coloanal anastomosis

Anorectal manometry and electromyography were studied in 17 patients before and after restorative proctocolectomy with stapled pouch-anal anastomosis, in ten patients before and after low anterior resection with stapled coloanal anastomosis, and in 35 normal controls. More than 80 per cent of patients in both groups developed abnormal oscillation of anal pressure after operation (amplitude 15-60 (median 25) cmH2O, frequency 4-10 (median 8) per min) and showed no anal relaxation in response to intermittent neorectal distension. All patients lost discriminative rectal sensation and none could perceive a normal desire to defaecate. Patients with postoperative soiling had a greater amplitude of anal pressure oscillation and lower minimum basal pressure, although those who underwent coloanal anastomosis had a greater risk of incontinence because of large asynchronous oscillations in neorectal pressure. The common pathophysiological features after restorative proctocolectomy and coloanal anastomosis probably relate to damage to the autonomic and enteric nerve supplies. The presence of an unstable internal anal sphincter may be an important cause of postoperative nocturnal incontinence.