A method of computerised isotope dynamic proctography.

Patients with long-standing constipation were examined by radioisotope proctography. A radiolabelled synthetic potato mash was inserted intrarectally and the dynamic changes during simulated defaecation recorded using a gamma-camera. Computer images from the stored data illustrate changes in the anorectal angle and pelvic floor. The median (and 95% confidence intervals) of the anorectal angles were: at rest 105 degrees (101 degrees, 116 degrees), on voluntary contraction of the pelvic floor by 'squeezing' 91 degrees (81 degrees, 98 degrees), on straining 120 degrees (107 degrees, 137 degrees) and during evacuation 126 degrees (116 degrees, 153 degrees). The pelvic floor movements were: pelvic floor ascent on voluntary contraction 28 mm (9, 34 mm), pelvic floor descent on straining -8 mm (-14, -4 mm) and descent during evacuation -27 mm (-34, -11 mm). Useful additions to previous methods are measurement of the completeness of rectal evacuation 58% (42, 77%), the defaecation time 64 s (50, 138 s) and the defaecation rate 0.9%/s (0.4, 1.4%/s).