Anal manometry: a comparison of techniques

Methods of anal manometry vary between centers, resulting in potential difficulties in interpretation of results. This study compared several accepted manometric techniques in healthy control subjects and in patients with fecal incontinence.

Eleven patients with fecal incontinence (M:F = 3:8; mean age = 67 years) and ten healthy control subjects (M:F = 3:7; mean age = 64 years) underwent anal manometry using five different methods: 1) water-perfused side hole; 2) water-perfused end hole; 3) microtransducer; 4) microballoon; 5) portable Peritron. Using a station pull-through technique, anal pressures (resting, squeeze, and cough pressures) were recorded at 1-cm intervals from rectum to anal verge, as well as radial pressures in four quadrants for Methods 1 and 2.

Water perfusion side hole recorded slightly higher maximal resting pressures; however, there were no significant differences between any of the methods. In healthy control subjects, distal maximal squeeze pressures were significantly higher (P < 0.05) than proximally as measured by microtransducer. There were slight (nonsignificant) variations in radial pressures with water perfusion and microtransducer. Peritron values for maximum resting pressure and maximum squeeze pressure were lower than those recorded by water perfusion side hole by a factor of 0.8.

There is no significant variation in anal pressure recordings using standard manometry techniques. Variations in radial pressures are slight and not significant in clinical studies. Results obtained with portable nonperfusion systems must be interpreted appropriately.