Patient lying on left side Inspect for anal fissure, external hemorrhoids, or other perineal abnormalities. Check perineal sensation and anocutaneous reflex (“anal wink”) using a cotton swab.

Patient bearing down, simulating defecation The perineum should relax and descend 1 to 3.5 cm; a minimal descent or paradoxical perineal rise suggests an inability to relax the pelvic floor muscles during defecation; an exaggerated descent suggests perineal laxity (e.g., childbirth, excessive straining attributable to chronic constipation). The anal sphincter should relax; paradoxical anal sphincter contraction suggests elevated sphincter pressure and anal stricture. Perineal “ballooning,” rectal prolapse, and prolapse of internal hemorrhoids are abnormal findings. Palpate the abdominal wall; excessive contraction suggests the Valsalva maneuver during defecation and ineffective effort.

Digital rectal examination while patient is relaxed Assess for increased anal sphincter tone, which may contribute to difficulty with evacuation. Palpate for anal fissure, tenderness, mass, stricture, rectocele, and hard stool.

Digital rectal examination while patient is instructed to try to expel finger Internal sphincter and puborectalis muscle should be felt to relax; tightening or lack of perineal descent suggests pelvic floor dyssynergia. Rectal propulsive force should be sufficient to expel finger.

Patient squatting, simulating defecation Rectal prolapse may not always be evident with the patient lying on his or her side, even when bearing down.