Doppler ultrasound of blood vessels in the placenta and uterus of pregnant women as a way of improving outcome for babies and their mothers

One of the main aims of routine antenatal care is to identify mothers or babies at risk of adverse outcomes. Doppler ultrasound uses sound waves to detect the movement of blood in blood vessels. It is used in pregnancy to study blood circulation in the baby, the mother's uterus and the placenta. If abnormal blood circulation is identified, then it is possible that medical interventions might improve outcomes. We set out to assess the value of using Doppler ultrasound of the mother's uterus or placenta (utero-placental Doppler ultrasound) as a screening tool. Other reviews have looked at the use of Doppler ultrasound on the babies' vessels (fetal and umbilical Doppler ultrasound). We also choose to look at women with low-risk and high-risk pregnancies, and in their first or second trimesters. This screening offers a potential for benefit, but also a possibility of unnecessary interventions and adverse effects. The review of randomised controlled trials of routine Doppler ultrasound of the uterus or placenta identified two studies involving 4993 women. All the women were in the second trimester of pregnancy and at low risk for hypertensive disorders. The studies were of good quality but small in size. We identified no improvements for the baby or the mother. However, more data would be needed to show whether maternal Doppler is effective, or not, for improving outcomes. We did not find any studies in the first trimester of pregnancy or in women at risk of high blood pressure disorders. More research is needed on this important aspect of care.

Authors' conclusions: 

Present evidence failed to show any benefit to either the baby or the mother when utero-placental Doppler ultrasound was used in the second trimester of pregnancy in women at low risk for hypertensive disorders. Nevertheless, this evidence cannot be considered conclusive with only two studies included. There were no randomised studies in the first trimester, or in women at high risk. More research is needed to investigate whether the use of utero-placental Doppler ultrasound may improve pregnancy outcome.

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Background: 

Impaired placentation can cause some of the most important obstetrical complications such as pre-eclampsia and intrauterine growth restriction and has been linked to increased fetal morbidity and mortality. The failure to undergo physiological trophoblastic vascular changes is reflected by the high impedance to the blood flow at the level of the uterine arteries. Doppler ultrasound study of utero-placental blood vessels, using waveform indices or notching, may help to identify the 'at-risk' women in the first and second trimester of pregnancy, such that interventions might be used to reduce maternal and fetal morbidity and/or mortality.

Objectives: 

To assess the effects on pregnancy outcome, and obstetric practice, of routine utero-placental Doppler ultrasound in first and second trimester of pregnancy in pregnant women at high and low risk of hypertensive complications.

Search strategy: 

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (June 2010) and the reference lists of identified studies.

Selection criteria: 

Randomised and quasi-randomised controlled trials of Doppler ultrasound for the investigation of utero-placental vessel waveforms in first and second trimester compared with no Doppler ultrasound. We have excluded studies where uterine vessels have been assessed together with fetal and umbilical vessels.

Data collection and analysis: 

Two authors independently assessed the studies for inclusion, assessed risk of bias and carried out data extraction. We checked data entry.

Main results: 

We found two studies involving 4993 participants. The methodological quality of the trials was good. Both studies included women at low risk for hypertensive disorders, with Doppler ultrasound of the uterine arteries performed in the second trimester of pregnancy. In both studies, pathological finding of uterine arteries was followed by low-dose aspirin administration.

We identified no difference in short-term maternal and fetal clinical outcomes.

We identified no randomised studies assessing the utero-placental vessels in the first trimester or in women at high risk for hypertensive disorders.

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