Medium- to Long-term Follow-up of Obstetric Anal Sphincter Injury

Abstract

Obstetric anal sphincter injury is the primary modifiable risk factor for anal incontinence in women. Currently, endoanal ultrasound is most commonly used to detect residual anal sphincter defects after childbirth. Translabial ultrasound has recently been introduced as a noninvasive alternative. This study aimed to determine medium- to long-term outcomes in women after obstetric anal sphincter injuries diagnosed and repaired at delivery. This is a cross-sectional study. This study was performed in a tertiary obstetric unit. Between 2005 and 2015, 707 women were diagnosed with obstetric anal sphincter injuries; 146 followed an invitation for follow-up. Clinical examination, anal manometry, and translabial ultrasound were performed. The primary outcomes measured were the St Mark incontinence score and the evidence of sphincter disruption on translabial ultrasound. Of 372 contactable patients, 146 attended at a mean follow-up of 6.6 years (1.7–11.9), of which 75 (51%) reported symptoms of anal incontinence with a median “bother score” of 6 (interquartile range, 3–8). Median St Mark score was 3 (interquartile range, 2–5). Twenty-four (16%) had a score of ≥5. Women who had been diagnosed with a 3c/4th degree tear had more symptoms (58% vs 44%), significantly lower mean maximal resting pressure (p < 0.001), maximal squeeze pressure (p < 0.001), and more residual external (p < 0.001) and internal (p = 0.012) sphincter defects in comparison with those who had a 3a/3b tear. Women with residual external sphincter defects had lower mean maximal squeeze pressure (p = 0.02). Residual internal sphincter defects (p = 0.001) and levator avulsion (p = 0.048) are independent risk factors for anal incontinence on multivariate modeling. This study was limited by the lack of predelivery data of bowel symptoms and BMI and incomplete intrapartum documentation of tear grade. Symptoms of anal incontinence were highly prevalent (51%), with a high bother score of 6. St Mark scores were associated with residual internal anal sphincter defects and levator avulsion. Women who had a higher tear grade showed a higher incidence of residual sphincter defects and lower manometry pressures. See Video Abstract at http://links.lww.com/DCR/A824.