PURPOSE: This study investigates the association between endoanal ultrasonography and anorectal manometry in relation to anal incontinence after primary repair of obstetric sphincter injury in primiparous, premenopausal women.
METHODS: The study population of this nested case-control study comprised 108 women who had previously been part of a randomized controlled trial comparing immediate with delayed primary repair of obstetric sphincter injuries, and who had been evaluated by anorectal manometry and endoanal ultrasound 1 year after their repair. Twenty cases and 88 controls were defined. Cases were defined as having a score greater than 2 on the Pescatori incontinence scale. Controls had a score of 2 or less. Ten obstetric, 9 ultrasonographic, and 7 manometric variables were studied.
RESULTS: Of the manometric variables, volume of first sensation and volume of first urge proved to be associated with anal incontinence at univariate statistical analysis. Volume of first sensation remained independently associated with anal incontinence after multivariate analysis. In addition, age, degree of tear, duration of second stage of labor, and a distal scar at ultrasound proved to be independently associated with anal incontinence.
CONCLUSIONS: Impaired rectal sensation at anorectal manometry and a distal scar at endoanal ultrasonography are associated with anal incontinence 1 year after primary sphincter repair in primiparous women. Additional studies need to evaluate whether these findings are associated with increased risk of anal incontinence in women that are continent 1 year after primary repair.