Normal values in anal manometry and rectal sensation: a problem of range.

Anal manometry was performed in 80 individuals, mainly healthy volunteers, 40 men and 40 women aged 20-87, mean 45 years. An open-tip perfusion system employing a catheter with 4 sideports and a terminal balloon (to be inflated with air) was used. The maximum basal pressure (MBP) showed no significant difference between men and women (68 +/- 21 and 63 +/- 19 mmHg). With respect to the maximum squeeze pressure (MSP) a significant difference was found between men and women (183 +/- 73 and 102 +/- 36 mmHg, p less than 0.001). Both MBP and MSP decreased significantly with age (both p less than 0.001). The sphincter length was larger in men than in women (4.1 +/- 0.7 and 3.5 +/- 0.5 cm, p less than 0.001) and was related to BMP (p less than 0.002). The distension reflex seemed to change with age: the threshold volume increased (p less than 0.02), the pressure drop decreased (p less than 0.03), and the recovery time increased (p less than 0.001). The pressure drop was also related to MBP (p less than 0.005). The volume of rectal perception increased with age (p less than 0.005). Ultra-slow waves were related to MBP, and were only seen when MBP greater than 70 mmHg. No relationship was to be found between parity and MBP or MSP in women. In conclusion, anal pressures and sphincter length in normal individuals have a large range and vary with age and sex. The sensitivity of the rectum to balloon inflation decreases with age. When making therapeutic decisions in patients with anorectal disorders all these factors should be taken into account.