How to interpret a functional or motility test - defecography

Abstract

Defecography evaluates in real time the morphology of rectum and anal canal in a physiologic setting by injection of a thick barium paste into the rectum and its subsequent evacuation. Because of its ability of structural and functional evaluation, defecography is primarily performed for work up of patients with longstanding constipation, unexplained anal or rectal pain, residual sensation after defecation or suspected prolapse. Technique and interpretation of this examination are outlined in this review.

Keywords: Constipation; Defecation; Defecography; Pelvic floor.

Figure 1

Measurement of anorectal angle. Anorectal angle (curved arrow) is measured between the longitudinal axis of anal canal (AB) and the posterior rectum line parallel to the rectum longitudinal axis (CD). Double thin arrows show the position of the anorectal junction.

Figure 2

Normal defecography. At rest (A). Note the deeper impression exerted by the puborectal sling (arrow) and the cranial migration of the distal rectum during forced contraction (B). During straining with closed sphincters (C), caudal migration of the anorectal junction is seen (asterisk). During evacuation (D), the anal canal opens with loss of puborectalis impression.

Figure 3

Dyskinetic puborectalis muscle syndrome. Note abnormally deep puborectal impression (arrow) at rest (A) and at evacuation phase (B). During evacuation phase, there is lack of pelvic floor descent.