Fetal cerebral Doppler in the recognition of fetal compromise.
OBJECTIVE
To establish reference ranges for the human fetal middle cerebral artery pulsatility index (MCA PI) for the local obstetric population, and to compare computerised antenatal fetal heart rate (FHR) analysis with the MCA PI as indicators of fetal compromise.


METHODS
Prospective data collection for selected patients.


METHODS
High risk pregnancy unit of a teaching hospital.


METHODS
Group 1 consisted of 18 healthy women with uncomplicated singleton pregnancies. Group 2 consisted of 27 women admitted to the high risk pregnancy unit over a 9 month period with intrauterine growth retardation and other related problems; all these women were delivered by prelabour caesarean section.


METHODS
Serial Duplex sonography to determine fetal MCA PI in Groups 1 and 2. Serial FHR analysis using computerised numerical techniques in Group 2 only.


METHODS
Serial MCA PI values from 24 to 39 completed weeks of gestation in Group 1. Comparison of serial MCA PI values with FHR analysis in relation to fetal outcome in Group 2.


RESULTS
In Group 1 the MCA PI diminished significantly as gestation advanced from 1.73 (SD 0.25) at 24 weeks to 1.38 (SD 0.26) at 39 weeks (P < 0.01). In Group 2 eleven babies were hypoxaemic at delivery: all had low MCA PI values while only nine had an abnormal FHR prior to delivery.


CONCLUSIONS
In normal pregnancy, there is a fall in the fetal MCA PI with advancing gestation which probably reflects a decreasing vascular resistance to fetal cerebral blood flow. Hypoxaemia at delivery appeared to be better recognised by the fetal MCA flow velocity waveform than the FHR analysis. This increased sensitivity, however, was achieved at the expense of a reduced specificity. Larger studies are needed to confirm the findings of this preliminary investigation.
Chandran
R
R
Dept of Obstetrics & Gynaecology, Medical Faculty, Universiti Kebangsaan Malaysia, Kuala Lumpur.
Serra-Serra
V
V
Sellers
S M
SM
Redman
C W
CW
D000328:Adult; D002536:Cerebral Arteries / Q000000981:diagnostic imaging*; D005260:Female; D005315:Fetal Diseases / Q000000981:diagnostic imaging*; D005317:Fetal Growth Retardation / Q000000981:diagnostic imaging; D005865:Gestational Age; D006340:Heart Rate, Fetal / Q000502:physiology*; D006801:Humans; D015588:Observer Variation; D011247:Pregnancy; D011446:Prospective Studies; D011674:Pulse; D012016:Reference Values; D012307:Risk Factors; D016216:Ultrasonography, Prenatal