Lower uterine segment thickness to prevent uterine rupture and adverse perinatal outcomes: a multicenter prospective study - 15/07/16

Doi : 10.1016/j.ajog.2016.06.018

Nicole Jastrow, MD ^a, Suzanne Demers, MD ^b, Nils Chaillet, PhD ^d, Mario Girard, RT ^b, Robert J. Gauthier, MD ^d, Jean-Charles Pasquier, MD, PhD ^e, Belkacem Abdous, PhD ^c, Chantale Vachon-Marceau, MD ^b, Sylvie Marcoux, MD, PhD ^c, Olivier Irion, MD ^a, Normand Brassard, MD ^b, Michel Boulvain, MD, PhD ^a, Emmanuel Bujold, MD, MSc ^b,^c,^⁎
^a Department of Obstetrics & Gynaecology, Faculty of Medicine, Hôpitaux Universitaires de Genève, Université de Genève, Switzerland
^b Department of Obstetrics & Gynaecology, Faculty of Medicine, Centre de recherche du Centre hospitalier universitaire de Québec, Université Laval, Québec, QC, Canada
^c Department of Social and Preventive Medicine, Faculty of Medicine, Université Laval, Québec, QC, Canada
^d Department of Obstetrics & Gynaecology, Faculty of Medicine, Hôpital Sainte-Justine, Université de Montréal, Montréal, QC, Canada
^e Department of Obstetrics & Gynaecology, Faculty of Medicine, Université de Sherbrooke, Sherbrooke, QC, Canada

^∗Corresponding author: Emmanuel Bujold, MD, MSc, FRCSC.

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Abstract

Background

Choice of delivery route after previous cesarean delivery can be difficult because both trial of labor after cesarean delivery and elective repeat cesarean delivery are associated with risks. The major risk that is associated with trial of labor after cesarean delivery is uterine rupture that requires emergency laparotomy.

Objective

This study aimed to estimate the occurrence of uterine rupture during trial of labor after cesarean delivery when lower uterine segment thickness measurement is included in the decision-making process about the route of delivery.

Study Design

In 4 tertiary-care centers, we prospectively recruited women between 34 and 38 weeks of gestation who were contemplating a vaginal birth after a previous single low-transverse cesarean delivery. Lower uterine segment thickness was measured by ultrasound imaging and integrated in the decision of delivery route. According to lower uterine segment thickness, women were classified in 3 risk categories for uterine rupture: high risk (<2.0 mm), intermediate risk (2.0–2.4 mm), and low risk (≥2.5 mm). Our primary outcome was symptomatic uterine rupture, which was defined as requiring urgent laparotomy. We calculated that 942 women who were undergoing a trial of labor after cesarean delivery should be included to be able to show a risk of uterine rupture <0.8%.

Results

We recruited 1856 women, of whom 1849 (99%) had a complete follow-up data. Lower uterine segment thickness was <2.0 mm in 194 women (11%), 2.0–2.4 mm in 217 women (12%), and ≥2.5 mm in 1438 women (78%). Rate of trial of labor was 9%, 42%, and 61% in the 3 categories, respectively (P<.0001). Of 984 trials of labor, there were no symptomatic uterine ruptures, which is a rate that was lower than the 0.8% expected rate (P=.0001).

Conclusion

The inclusion of lower uterine segment thickness measurement in the decision of the route of delivery allows a low risk of uterine rupture during trial of labor after cesarean delivery.

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Key words : lower uterine segment, uterine rupture, vaginal birth after cesarean delivery

Plan

Materials and Methods

Study design and participants

	Supported by the Canadian Institutes of Health Research (operating grant #210974), the Geneva University Hospitals (PRD #09-II-28), and the Jeanne et Jean-Louis Levesque Perinatal Research Chair at Université Laval, Canada. S.D. and E.B. hold a Researcher’s salary award from the Fonds de la Recherche du Québec–Santé.
	The authors report no conflict of interest.
	Cite this article as: Jastrow N, Demers S, Chaillet N, et al. Lower uterine segment thickness to prevent uterine rupture and adverse perinatal outcomes: a multicenter prospective study. Am J Obstet Gynecol 2016;•••:••••.