Prediction of pre-eclampsia by abnormal uterine Doppler ultrasound and modification by aspirin.

OBJECTIVE: To assess the effect of low dose aspirin on severe pre-eclampsia when given to women identified as high risk by abnormal uterine artery Doppler ultrasound. DESIGN: Women with abnormal uterine artery flow velocity waveforms were recruited to the CLASP trial at 24 weeks. Abnormal uterine artery waveforms, with a high resistance index or an early diastolic notch, were identified at the 18-22 week anomaly scan and confirmed at 24 weeks. Of those women with persistently abnormal waveforms, 63 agreed to enter the CLASP trial. Three women were lost to follow up and five did not comply. Thus, 60 were randomised: 29 to placebo and 31 to low dose aspirin (60 mg daily) and analysis by intention to treat is reported. RESULTS: There were nine cases (29%) of pre-eclampsia in the aspirin group and twelve (41%) in the placebo group (odds ratio (OR) 0-58, confidence interval (CI) 0.2-1.69, P = 0.32). Severe pre-eclampsia developed in four women in the aspirin group and eleven women in the placebo group (OR 0.24, CI 0.07-0.88, P = 0.03) and intrauterine growth retardation occurred in eight cases in the aspirin group and twelve in the placebo group (OR 0.49, CI 0.17-1.47). The mean birthweight and gestation at delivery were 2.69 kg and 38.5 weeks in the aspirin group and 2.38 kg and 37.4 weeks in the placebo group, neither of which were statistically significant using the unpaired t test; P = 0.09 and P = 0.23, respectively. CONCLUSION: In high risk pregnancy low dose aspirin commenced at 24 weeks may reduce the incidence of severe pre-eclampsia.

Uterine artery blood flow response to correction of amniotic fluid volume.

OBJECTIVE: Our purpose was to investigate whether acute alterations of amniotic fluid volume affect uteroplacental perfusion. STUDY DESIGN: Three groups of patients of comparable gestational age were studied in a fetal medicine referral unit: (1) eight pregnancies with severe polyhydramnios because of twin-twin transfusion syndrome undergoing therapeutic amnioreduction, (2) seven with severe oligohydramnios undergoing diagnostic amnioinfusion, and (3) six control women having invasive procedures of similar duration without manipulation of amniotic fluid volume. Color Doppler imaging was used to measure uterine artery impedance index values and quantitative blood flow before and within 15 minutes of the end of the procedure. RESULTS: Quantitative flow measurements increased after amnioreduction (74% median increase of volume flow, range 22% to 329%, p < 0.01) and decreased after amnioinfusion (33% median decrease of volume flow, range 17% to 51%, p < 0.05). Impedance index values increased after amnioinfusion (25% median increase in pulsatility index, range 4% to 71%, p < 0.05) and did not alter with amnioreduction. There were no significant changes in the control group. CONCLUSION: Acute changes in amniotic fluid volume alter uteroplacental perfusion. In twin-twin transfusion syndrome amelioration in uterine flow may improve fetal condition and explain in part the success of serial amnioreduction therapy.