Prolonged Second Stage of Labor and Anal Sphincter Injury in a Contemporary Cohort of Term Nulliparas

Abstract

Objective This study aimed to assess whether a prolonged second stage of labor is an independent predictor of obstetric anal sphincter injury (OASI) in a contemporary cohort of nulliparous and term parturients, and to evaluate whether predelivery factors can accurately predict OASI. Study Design This was a nested case-control study within a cohort of consecutive nulliparous term parturients with a singleton gestation who underwent a vaginal delivery at a single institution between January 2014 and January 2015. Cases were defined as women with a third- or fourth-degree laceration at the time of delivery, and controls were women without a third- or fourth-degree laceration. A prolonged second stage was defined as a second stage of ≥3 hours. Univariable and multivariable regression analyses were performed to examine the relationship between prolonged second stage of labor and third- or fourth-degree lacerations. Receiver operator curves were developed to assess the predictive capacity of predelivery information for third- and fourth-degree lacerations. Results Of 1,197 births, 63 women had third- or fourth-degree lacerations (5.3%). With each additional hour of the second stage, the rate of OASI increased, with 2.9% of women with a second stage of <1 hour with OASI, 3.5% between 1 and 2 hours, 5.7% between 2 and 3 hours, 7.8% between 3 and 4 hours, 16.1% between 4 and 5 hours, and 28.6% among women with a second stage length >5 hours (p < 0.001). In multivariable regression analysis, operative vaginal delivery (adjusted odds ratio [aOR] = 5.92, 95% confidence interval [CI]: 3.17–11.07) and a prolonged second stage (aOR = 1.92, 95% CI: 1.06–3.51) were independent predictors of third- and fourth-degree lacerations. A predictive model was developed from these results (area under the curve [AUC] = 0.75, 95% CI: 0.68–0.81). Conclusion Prolonged second stage of labor is a predictor of OASI, after adjustment for operative vaginal delivery. A model using predelivery risk factors has a reasonable prediction of OASI. Key Points

Duration of the active first stage of labour and severe perineal lacerations and maternal postpartum complications: a population‐based cohort study

“…The risks of caesarean delivery (CD), operative vaginal delivery, and maternal complications, including postpartum haemorrhage, chorioamnionitis, endometritis, postpartum fever and advanced perineal lacerations, increase when the second stage duration is prolonged. [8][9][10][11][12][13] The effect of active first stage duration is less investigated, which is of concern as labour is a continuous process and its first and second stages are closely interrelated. 14,15 The few studies that exist have indicated an association between active first stage duration and composite adverse maternal outcomes.…”

“…A longer second stage labour duration has been associated with increased maternal morbidity in numerous studies. The risks of caesarean delivery (CD), operative vaginal delivery, and maternal complications, including postpartum haemorrhage, chorioamnionitis, endometritis, postpartum fever and advanced perineal lacerations, increase when the second stage duration is prolonged 8–13 . The effect of active first stage duration is less investigated, which is of concern as labour is a continuous process and its first and second stages are closely interrelated 14,15 .…”

Substantial Obstetric Anal Sphincter Injury during Vacuum Assisted Delivery: An Obstetrical Issue or Device Related?

“…The incidence of OASIS in modern obstetric practice varies in different populations, ranging from an incidence of less than 1% to an incidence of 6% [ 1 , 2 , 3 , 4 ]. The risk factors for OASIS are similar worldwide and include primiparity, birthweight >4000 g, instrumental assisted deliveries, persistent occiput posterior presentation, a prolonged second stage of labor, median episiotomy, and previous OASIS [ 4 , 5 , 6 , 7 , 8 , 9 , 10 ]. In addition, there is controversy about other possible risk factors such as vaginal birth after a cesarean section, maternal age, ethnicity, and more.…”

Prolonged passive second stage of labour in nulliparous women: A multi perspective study

“…There is a large number of studies describing birth outcomes in relation to the second stage, but most of them lack a division of the passive and active second stage. A prolonged second stage has been associated with adverse maternal outcomes: postpartum haemorrhage (PPH), infection, obstetric anal sphincter injury (OASI) (71), IB, CS, and episiotomies (72)(73)(74)(75)(76)(77)(78)(79) in nulli-and parous women. A new policy in labour management in the United States in 2014 aimed to reduce the CS rate for nulliparous women by adding an additional hour before diagnosing a prolonged second stage.…”