The pressure area: a variable for the assessment of anal sphincter function.

OBJECTIVE

To assess the contribution of the area under the resting and squeeze pressure curves, respectively, in the measurement of anal sphincter function.

DESIGN

Open study.

SETTING

University hospital, Sweden.

SUBJECTS

106 Healthy volunteers (73 women and 33 men) with no signs or symptoms of anorectal disease.

INTERVENTIONS

Anorectal manometry with a microtransducer.

OUTCOME MEASURES

Maximal resting and squeeze pressures. Resting and squeeze pressure areas were calculated in the interval 0-5 cm from the anal verge.

RESULTS

There was no difference in mean(SD) resting pressure (mmHg) between men (50(17)) and women (47(15)) but there was a significant difference in the mean(SD) resting pressure area (units) (149(46) compared with 125(46)). The squeeze pressure was significantly higher in men (193(57)) than in women (115(42), t = 7.72, p < 0.001). The difference between the sexes was even more pronounced when the squeeze pressure areas were compared: (624(216) and 318(114), respectively, t = 9.50, p < 0.001).

CONCLUSION

Both the pressure values and the high pressure zone should be considered in the interpretation of the results of anorectal manometry. The pressure area includes both aspects and showed a greater separation between men and women than the peak pressure value alone.