Doppler ultrasound in obstetrics

Intrauterine fetal growth restriction

Rhesus disease

Twin-to-twin transfusion syndrome

Gestational diabetes

Fetal macrosomia

Abnormal UA doppler directly correlates with a lower number of placental arteries per high power field

Abnormal UA doppler predicts fetal compromise with a lead time of 3 days after diagnosis

Diagnosis of abnormal UA doppler ultrasound affords time for useful interventions to be instituted to prolong pregnancy

Serial UA dopplers should be used from 32 weeks in high risk pregnancies

Absent end-diastolic flow in the umbilical artery is a trigger for delivery in a fetus <32 weeks

MCA doppler assessment is of similar efficacy in both IUGR-affected pregnancies and the prediction of fetal anaemia in Rhesus isoimmunisation

In IUGR there is 'brain sparing' effect, leading to an increased diastolic flow, hence reduction in PI.

The MCA PI/ UA PI ratio (cerebro-placental ratio) is more sensitive than either measurement in isolation

MCA doppler is equally useful in both early and late-onset IUGR

DV doppler acts as a marker of cardiovascular deterioration

Absence or reversal of A-wave in early IUGR is a strong predictor of fetal acidaemia

There are clear RCT data and consensus around use of DV and timing of delivery of the IUGR fetus

Aortic isthmus doppler abnormalities may precede DV changes, often by one week

Umbilical vein doppler abnormalities may predict right heart failure and myocardial hypoxia

MCA PSV can predict the existance of moderate to severe fetal anaemia with a sensitivity of 100% and false positive rate of 12%