Paradoxical contraction of pelvic floor muscles: clinical significance.

Paradoxical contraction of pelvic floor muscles during defecation straining has been said to be a cause of constipation and difficulty in passing feces. Nevertheless, controversies about its clinical significance still remained. Twenty patients with constipation and electromyographic evidence of paradoxical contraction of both puborectalis and external anal sphincter were investigated. An anorectal manometry performed in 17 confirmed the paradoxical contraction in 13 (76%). Electromyography revealed neurogenic signs in 11. Defecography demonstrated the paradoxical contraction in 6 only, but, together with barium enema and colon transit time, showed associated anorectal disorders in 9 patients. Twenty control patients were also studied. None had difficulty defecating. Nevertheless, 8 of them (40%) had paradoxical contraction. These observations suggest that paradoxical contraction of pelvic floor muscles may by asymptomatic and that another cause of emptying difficulties has always to be looked for.