Am J Perinatol 2022; 39(09): 0937-0943
DOI: 10.1055/s-0040-1718878
Original Article

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

Mariam Naqvi
1   Division of Maternal Fetal Medicine Department of Obstetrics and Gynecology, Cedars Sinai Medical Center, Los Angeles, California
2   Division of Maternal Fetal Medicine Department of Obstetrics and Gynecology, Massachusetts General Hospital, Boston, Massachusetts
,
3   Department of Maternal, Child, and Family Health, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina
4   Department of Social Medicine, Center for Bioethics, University of North Carolina, Chapel Hill, North Carolina
,
Ilona T. Goldfarb
2   Division of Maternal Fetal Medicine Department of Obstetrics and Gynecology, Massachusetts General Hospital, Boston, Massachusetts
,
Allison S. Bryant
2   Division of Maternal Fetal Medicine Department of Obstetrics and Gynecology, Massachusetts General Hospital, Boston, Massachusetts
,
Blair J. Wylie
2   Division of Maternal Fetal Medicine Department of Obstetrics and Gynecology, Massachusetts General Hospital, Boston, Massachusetts
5   Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Beth Israel Deaconess Medical Center, Boston, Massachusetts
,
Anjali J. Kaimal
2   Division of Maternal Fetal Medicine Department of Obstetrics and Gynecology, Massachusetts General Hospital, Boston, Massachusetts
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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

  • Prolonged second stage labor is associated with obstetric anal sphincter injury in term nulliparas.

  • Predelivery risk factors reasonably predict obstetric anal sphincter injury in term nulliparas.

  • Improved models are needed for clinical risk-stratification.



Publikationsverlauf

Eingereicht: 18. Mai 2020

Angenommen: 16. September 2020

Artikel online veröffentlicht:
20. Oktober 2020

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