What causes chronic idiopathic perineal pain?

Chronic idiopathic perineal pain is poorly understood. Underlying structural abnormalities have been clinically suspected but rarely demonstrated objectively. The condition has been frequently considered to be a psychological disorder. We aimed to evaluate how commonly a structural explanation for such pain symptoms is present.

Patients seen in a pelvic floor clinic with severe chronic functional anorectal pain that was classified as chronic idiopathic perineal pain (study group) were prospectively registered in a pelvic floor database and underwent pelvic floor work up (defaecating proctography, anorectal physiology and anal ultrasound +/- rectal examination under anaesthetic). A control group was formed by patients with obstructed defaecation, with or without faecal incontinence, with advanced posterior compartment prolapse.

Of 59 patients with chronic idiopathic perineal pain [80% women; mean age 53 (range, 22-84) years], representing 5% of all pelvic floor presentations, 33 (56%) had chronic idiopathic perineal pain alone and 26 (44%) had chronic idiopathic perineal pain with obstructed defaecation. Thirty-five (59%) had an underlying high-grade internal rectal prolapse (73% with chronic idiopathic perineal pain + obstructed defaecation vs 48% with chronic idiopathic perineal pain alone; P < 0.05). Anorectal pain was present in 50% of 543 controls with advanced posterior compartment prolapse.

High-grade internal rectal prolapse commonly underlies chronic idiopathic perineal pain, particularly when obstructed defaecation is present. Chronic anorectal pain is a common, under-recognized subsidiary symptom in patients with advanced posterior compartment prolapse presenting primarily with obstructed defaecation or faecal incontinence.