Source: DGNews  |  Posted 3 years ago

SAN DIEGO -- January 30, 2009 -- In a study to be presented today at the Society for Maternal-Fetal Medicine's (SMFM) annual meeting, researchers will unveil findings that show that by using a sonogram to measure the lower uterine segment (LUS) thickness, they can predict uterine scar defects in women who had previous cesarean deliveries and anticipate which patients are at risk for subsequent uterine rupture if they attempt vaginal birth after c-section (VBAC).

According to statistics from the Centers for Disease Control and Prevention (CDC), 30.2% of all live births in the United States were cesarean deliveries in 2005. Since 1996, the total cesarean rate has increased by 46%, driven by both an increase in the percentage of all women having a first cesarean and a decline in the percentage of women delivering vaginally after a previous cesarean," the authors said.

Repeat cesarean deliveries are an obvious concern. "There is a growing concern about the increase in cesarean births because there is a body of evidence showing that they are associated with higher rates of maternal and infant complications," said lead author Emmanuel Bujold, MD, Department of Obstetrics & Gynecology, Universite Laval, Laval, Quebec. "There are far fewer complications to the mother and infants as a result of a vaginal birth, so it is important to determine when a patient with a history of prior cesarean section can have a vaginal birth safely."

The study looked at 236 women who had a prior cesarean delivery. Their LUS thickness was measured between 35 and 38 weeks of gestation. Researchers reported 3 cases of complete uterine rupture and 6 cases of uterine scar dehiscence.

Analysis demonstrated significant associations between the risk of uterine rupture during trials of labour and full LUS thickness. The combination of full LUS thickness under 2.3mm and a single-layer muscular closure was significantly associated with uterine rupture (relative risk: 21.8, 95% confidence interval [CI], 2.1-222; P<.0001) during labour.

"The study results will help us predict, for patients who have given birth through cesarean section before, which ones are at high risk for uterine rupture during labour in a subsequent pregnancy," said Dr. Bujold. "That will help us better advise women about having a vaginal birth the next time."

SOURCE: Society for Maternal-Fetal Medicine