Do hot baths promote anal sphincter relaxation?

Hot perineal baths have been prescribed for the treatment of painful anorectal conditions such as anal fissures and perianal hematomas or for the postoperative care of hemorrhoidectomy. Despite this widely accepted benefit, no studies have been performed to determine whether there is a rational explanation for this procedure. Anorectal manometry was performed in 40 control subjects with no anorectal complaints before and after a hot perineal bath. No significant difference was found between anal pressures at rest or during voluntary contraction before and after the bath. We conclude from this study that no relaxation of anal sphincters can be obtained by hot perineal baths in normal subjects.