Doppler ultrasound of the fetomaternal circulation: a preliminary study on differences between ethnic groups

The aim of this study was to investigate whether the same reference values might be used for the pulsatility index obtained by Doppler examinations of the fetal umbilical and middle cerebral artery and the maternal uterine arteries in autochthonous Belgian, Turkish and Moroccan women in Belgium. Notching of the uterine artery was also studied in the three ethnic groups.

Doppler measurements were performed in 206 autochthonous Belgian, 36 Moroccan and 36 Turkish pregnant women between 20 and 24 weeks gestational age for the umbilical artery, middle cerebral artery and uterine arteries. The mean uterine artery pulsatility index and the placentocerebral index were calculated. Intra-observer variation was calculated by repeat measurements on 20 videotaped examinations and intrapatient variation was determined by repeat examination in 60 patients.

Maternal length was higher and body mass index lower in Belgian women; more of these admitted smoking during pregnancy. There were no statistically significant inter-ethnic differences for the pulsatility index of the umbilical artery, middle cerebral artery, placental-site uterine artery and the placentocerebral index. The pulsatility index in the non-placental-site uterine artery and the mean uterine artery was lower in the Moroccan group. Intra-patient variation expressed as intra-patient standard deviation of the umbilical and middle cerebral artery pulsatility index was relatively large compared to inter-patient variation, being 57% to 88% of the inter-patient standard deviation. This was not the case for the uterine artery. Notching of the uterine artery was not contributive for the prediction of intrauterine growth restriction or preeclampsia in these ethnic groups.

Only small statistically significant differences were demonstrated. For clinical practice, the use of different reference charts for fetomaternal Doppler measurement in Belgian, Turkish and Moroccan women is not warranted.