Evidence from dynamic integrated proctography to redefine anismus

Tzhe role of anismus in the aetiology of defective rectal evacuation was investigated by dynamic integrated proctography in 20 controls and 71 constipated patients. Normal parameters were defined and compared between 21 constipated patients with poor evacuation during proctography ( 90 per cent of contrast evacuated; group 2). Nine patients in group 1 failed to evacuate. Radiological abnormalities of the rectum were recorded in all groups but obstructed evacuation was not observed. Anismus (defined as a recruitment of puborectalis electromyogram (EMG) activity of >50 per cent) was significantly more common in group 1 than group 2 patients (14 of 21 versus 12 of 50, P 50 cmH2O compared with two in group 2 (P 50 per cent; evidence of an adequate level of intrarectal pressure (>50 cmH2O) on straining; and presence of defective evacuation.