Risk factors for anal sphincter disruption during child birth.

BACKGROUND AND AIMS: The objective of our study was to analyse the risk factors in a cohort of women who suffered anal sphincter disruption (third-degree tear) and compare the results with a similar cohort of women who underwent an uncomplicated vaginal delivery (without a clinically detectable laceration) during the same period. MATERIALS AND METHODS: A retrospective analysis was carried out on 54 women (group 1) who suffered a third-degree tear and 71 women who had undergone uncomplicated vaginal delivery during the same period (group 2). The risk factors considered were forceps delivery, parity, second stage of labour longer than 1 h, episiotomy, birth weight over 4 kg, gestational age and maternal age at delivery. The Cleveland Incontinence Score was completed. RESULTS: Multiple logistic regression analysis of obstetric risk factors for third-degree perineal tear indicated forceps delivery (p = 0.0001), primiparity (p = 0.004), foetal birth weight over 4 kg (p = 0.030) and delay in the second stage of labour (p = 0.031) to be significant risk factors for a third-degree tear. Mediolateral episiotomy was shown to be a significant protective factor (p = 0.0001). Gestational age and the maternal age at delivery (p = 0.340) were not shown to be significant risk factors (p = 0.336). CONCLUSION: Primary prevention and identification of women with risk factors is recommended. In some cases, counselling regarding the potential risks and benefits of both vaginal and caesarean delivery may be appropriate.