Using C-Section Scars to Predict Future Deliveries
Jan. 31 -- FRIDAY, Jan. 30 (HealthDay News) -- Measuring the thickness of the uterine scar from a cesarean delivery can help physicians predict which women would be at low risk for uterine rupture and may safely try to have a vaginal delivery, according to a new study by Canadian researchers.
"The thicker the scar is, the stronger the scar is, and the smaller the chance of rupture," said Dr. Emmanuel Bujold, associate professor of obstetrics and gynecology at the University of Laval in Quebec, Canada. Bujold is the lead author of the study, which was expected to be presented Jan. 30 at the Society for Maternal-Fetal Medicine's annual meeting in San Diego.
The issue of repeat cesarean deliveries is of concern, because delivery of a baby by C-section has been linked to higher rates of complications for both mother and infant, Bujold said.
C-section rates have been climbing in the United States and elsewhere. In 2006, about a third of births were by cesarean, with 1.3 million cesarean births and almost 3 million vaginal deliveries, according to the U.S. National Center for Health Statistics.
In deciding which women can safely try a vaginal birth after a C-section, doctors must decide if a vaginal delivery would be safe or if risks -- such as uterine rupture -- would make it unwise.
Bujold's study involved 236 pregnant women who had delivered previously by C-section but who planned a vaginal delivery. They used ultrasound to measure the lower part of the uterus, which correlates with scar thickness from the previous C-section, and then followed the women through their deliveries.
During labor and delivery, three of the women had a complete uterine rupture. In six, the scar reopened. Women who had uterine rupture had a very thin scar, Bujold said.
"We found the cutoff is probably 2.3 millimeters" in terms of scar thickness, he said. The average risk of rupture is about 1 percent, Bujold said, but in the study, "if you had a scar smaller than 2 mm, your risk of rupture [was] about 10 percent."
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