Ultrasound During Active Labor Aids C-Section Prediction

A new study describes a model to predict vaginal or cesarean delivery based on maternal characteristics and the results of intrapartum ultrasound.

Researchers at St. Olavs Hospital (Trondheim, Norway), Addenbrooke’s Hospital (Cambridge, United Kingdom), and other institutions conducted a prospective observational study involving 122 nulliparous women in the first stage of labor, with the intent of developing a model to predict vaginal delivery using ultrasound. The model includes information on maternal age, body mass index (BMI), length of pregnancy, head-perineum distance, occiput posterior position, fetus rotation in the birth canal, and caput succedaneum (the swelling of the fetus' scalp).

Fetal head position was assessed with transabdominal ultrasound and cervical dilatation was assessed by digital examination; transperineal ultrasound was used to determine head-perineum distance and the presence of caput succedaneum. The women were divided into equal study and validation cohorts. A risk score for vaginal birth was developed, which was dichotomized into no (cesarean delivery) and yes (vaginal birth). The results showed that women with a derived dichotomized score above the median had greater than 10 times the odds of undergoing vaginal delivery. The study was published in the September 2015 issue of the American Journal of Obstetrics and Gynecology.

“Among first-time mothers, about 30% of deliveries go slowly. Labor can stop or slow down if the contractions are too bad, if the baby is big, if the birth canal is too narrow, or if the fetus is in the wrong position. It is important to determine the main reason,” said lead author Torbjorn Moe Eggebo, MD, chief physician at the National Center for Fetal Medicine at St. Olavs Hospital. “Some fetuses are called stargazers because they're lying face up in relation to the mother's womb when they come out. These births often take a long time, and more often end up as C-section deliveries.”

“Many women find it unpleasant to have a vaginal examination using fingers. Using ultrasound in the delivery room can reduce the number of vaginal examinations, and probably also the risk of infection during birth; and errors occur in at least 20% of clinical assessments compared to only 2% using ultrasound,” added Dr. Eggebo. “The women also get information on how the delivery is going, and they're able see images on the screen that show how the fetus is moving during contractions. It's easy to teach midwives and physicians to use these small ultrasound devices.”

The number of caesarean sections performed in different parts of the world varies greatly. In Brazil, for example, over 50% of all children are delivered by caesarean section, often without a thorough reason. In the United States, the frequency is 33%, while in Norway the frequency is 17%-18%. In outlying areas of many African countries, on the other hand, only one percent of babies come into the world through caesarean section, leading to maternal mortality. In Sierra Leone, a woman's lifetime risk of dying during pregnancy and childbirth is 15%.

Related Links:
St. Olavs Hospital
Addenbrooke’s Hospital