Alteration of anal sphincter morphology following vaginal delivery revealed by multiplanar anal endosonography.

Abstract

To assess morphologic change in the anal sphincters in the absence of endosonographic evidence of trauma after vaginal delivery. Prospective observational study. District general hospital. Consecutively booked nulliparous pregnant women attending antenatal clinic. All women were examined using three-dimensional anal endosonography, simple manometry and had questionnaire assessment of incontinence before and after delivery. Components of the anal canal were measured in the axial, sagittal and coronal planes and paired pre- and post-delivery examinations were compared. Any changes were related to changes in continence and anal canal manometry. Twenty-two women had a vaginal delivery and no endosonographic evidence of perineal trauma after delivery. After delivery, there was significant shortening of the length of the anterior external anal sphincter [EAS] (mean 21.7 vs 20.5 mm, P = 0.02) when measured in the sagittal plane, which increased in anterior angulation with respect to the axis of the anal canal (10 degrees vs 13.8 degrees, P = 0.03). In the axial plane, no change was seen in the thickness of any of the sphincter components after delivery. None of these morphologic changes correlated with changes in manometry or continence score. Anal sphincter morphology changes after an otherwise atraumatic vaginal delivery. This change does not correlate with any functional symptoms.