Study: Doppler ultrasound in pregnancy reduces threat in high-risk groups

Current evidence suggests that using Doppler ultrasound in high-risk pregnancies to monitor a fetus' health may reduce Caesarean sections and the number of babies who die, according to research published today in the Cochrane Systematic Review.

Doppler ultrasound is a well-established technique used to diagnose problems during pregnancy, according to the authors. Doppler ultrasound can monitor how fast blood is moving in the umbilical blood flow and can be used to evaluate whether the blood flow is normal--indicating that the fetus is healthy--or abnormal, which indicates that the fetus is under stress.

The purpose of using Doppler is to reduce risk to the baby. However, according to the researchers, some experts argue that it may prompt some unnecessary early interventions.

Zarco Alfirevic, MD, professor of fetal and maternal medicine at the University of Liverpool in England, and colleagues included 18 studies which together included 10,000 women in high-risk groups, including those who had previously lost babies during pregnancy, those carrying growth restricted babies and women with hypertension or diabetes.

Women who were examined with Doppler ultrasound were compared with those who had no Doppler or with those who had cardiotocography, which monitors the baby's heartbeat.

The researchers found that Doppler reduced infant deaths, possibly through better timing of caesarean sections, as well as reducing the number of Caesarean sections themselves and inductions of labor. However, the researchers wrote that the studies included were of “questionable quality.”

"A case could certainly be made for a higher quality, multi-center trial of Doppler ultrasound than we have so far seen," said Alfirevic. "It is quite possible that for some so-called high risk groups fetal Doppler offers little or no benefit. Women with diabetes are one such group where fetal Doppler may, in fact, give false reassurance.

"It is important to point out, of course, that it is the clinical decision that follows a Doppler ultrasound examination that changes the outcome for the baby, and currently there is little agreement on what intervention should follow an abnormal Doppler finding," Alfirevic concluded.