Anal sphincter damage after vaginal delivery using three-dimensional endosonography

Objective: To determine the incidence and functional consequences of extern al sphincter trauma compared with other perineal structures using a novel i maging technique, three-dimensional endosonography. Methods: Fifty-five nulliparous women (mean age 30 years, range 18-47 years ) had three-dimensional anal endosonography, anal manometry, and questionna ire assessment of continence at a median gestation of 33 weeks (23-42 weeks ) and 10 weeks (7-22 weeks) after delivery. Results: There was ultrasound evidence of postpartum trauma in 13 of 45 wom en who had a vaginal delivery (29%, confidence interval [CI] 16%, 44%), inv olving the external sphincter in five (11%, CI 4%, 24%), the puboanalis in nine (20%, CI 10%, 35%), and the transverse perineii in three (7%, CI 1%, 1 8%). In four, more than one structure was damaged. External sphincter traum a was associated with a significant decrease in squeeze pressure (P =.035) and an increase in incontinence score (P =.02) compared with those without trauma. Tears to the puboanalis or transverse perineii only did not affect pressure or incontinence scores. Coronal imaging of the external anal sphin cter was a useful adjunct to the assessment of trauma. Conclusion: The overall incidence of trauma to the sphincter complex was si milar to that of previous reports, although actual damage to the external s phincter was less common and represented the only functionally significant component. (Obstet Gynecol 2001;97:770-5. (C) 2001 by The American College of Obstetricians and Gynecologists.).