Risk factors for obstetric anal sphincter injuries during vaginal delivery: can we reduce the burden?

Abstract

Background: Third-and fourth-degree perineal tears are associated with significant discomfort and impact on women's quality of life after labor. We reviewed the literature on risk factors for obstetric anal sphincter injuries (OASIS), focusing on modifiable risk factors for OASIS to help obstetricians prevent them. Methods: We searched MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Scopus using key search terms. We selected clinical studies, systematic reviews, and meta-analyses in English investigating antepartum and intrapartum factors associated with OASIS. Three researchers independently selected studies and documented outcomes. Results: We identified forty-two relevant articles for inclusion. Among antepartum factors, primiparity, neonatal birth weight, and ethnicity were associated with a higher risk of OASIS. Instrumental delivery, midline episiotomy, duration of the second stage of labor, persistent occiput posterior position, and labor augmentation were those intrapartum factors reported associated with OASIS. Conclusions: Multiple anteand intrapartum factors are associated with a higher risk of OASIS. The actual modifiable factor is episiotomy during the second stage of labor. However, literature reporting episiotomy associated with a reduction in OASIS prevalence during instrumental delivery is limited. These results may help obstetricians recognize women at higher risk of developing severe perineal tears and recommend further investigation on the role of episiotomy in an operative delivery.

Comparison of Maternal Labor-Related Complications and Neonatal Outcomes Following Elective Induction of Labor at 39 Weeks of Gestation vs Expectant Management

“…While these findings are encouraging, most studies have focused on perinatal outcomes (except for rates of cesarean section and operative birth). There have been very few studies on the impact of induction at 39 weeks on maternal labor-related complications, such as perineal injury and postpartum hemorrhage . Additionally, many previous studies have excluded women with a high body mass index (BMI [calculated as weight in kilograms divided by height in meters squared]) or those undergoing a trial of labor after cesarean section.…”

“…There have been very few studies on the impact of induction at 39 weeks on maternal labor-related complications, such as perineal injury and postpartum hemorrhage. 15 , 16 , 17 Additionally, many previous studies have excluded women with a high body mass index (BMI [calculated as weight in kilograms divided by height in meters squared]) or those undergoing a trial of labor after cesarean section. This study aimed to investigate maternal labor-related complications following elective induction at 39 weeks of gestation compared with expectant management and included nulliparous and multiparous women as well as those with a high BMI or those undergoing a trial of labor after cesarean section.…”