The internal sphincter and Lord's procedure for haemorrhoids.
Anal pressure and motility have been measured in 56 patients with haemorrhoids and 40 asymptomatic subjects. The anal pressure of patients with haemorrhoids (93-6 cm H2O) was very significantly higher than that of the controls (66-8 cm H2O; P less than 0-001). Ultra-slow pressure waves (amplitude 25-100 cm H2O, frequency 0-9-1-6/min) were present in 39 per cent of patients with haemorrhoids, but in only 7-5 per cent of the controls (P less than 0-001). Ultra-slow waves are present under anaesthesia with the voluntary muscles paralysed and are associated with the highest anal pressure, and so, represent abnormal activity of the internal anal sphincter. Measurements after anal dilatation showed complete abolition of ultra-slow wave activity and a very significant drop in pressure. One year after dilatation 19 patients had a mean anal pressure of 62 cm H2O. Very good results were obtained unless the haemorrhoids were so large that they prolapsed at times other than defaecation. Lord's procedure is a rational treatment since it corrects an underlying overactivity of the internal sphincter.