OBSTRUCTIVE DEFECATION AND SLOW TRANSIT CONSTIPATION - THE PROCTOGRAPHIC PARAMETERS

Twenty-two patients with functional obstructive defaecation were compa red with seven patients with slow transit constipation using isotope p roctography. The obstructive defaecation patients were unable to perfo rm a complete rectal evacuation (% of the activity evacuated: 54%). Th e defaecation time in this group was prolonged (120 s) with a lower de faecation rate (0.5%/s) compared with the slow transit constipation su bjects (32 s and 1.8%/s). The anorectal angle (ARA) on straining did n ot change in the obstructive defaecation patients but became more obtu se in the slow transit constipation subjects (P < 0.02). The pelvic fl oor (PF) descent on straining and evacuation was greater in obstructiv e defaecation patients compared with the slow transit constipation one s (P < 0.01). Obstructive defaecation is characterised by prolonged de faecation and reduced defaecation rate compared with slow transit cons tipation. Obstructive defaecation patients present with more acute ARA s on straining, and abnormal perineal descent in contrast to the slow transit constipation ones.