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[Effect of heparin on the ratio of peak systolic to least diastolic flow velocity of umbilical artery at second-trimester pregnancies].

OBJECTIVE
To evaluate the efficiency of heparin on the ratio of peak systolic to least diastolic flow velocity (S/D) of umbilical artery flow velocity waveforms at second-trimester pregnancies.


METHODS
Sixty-seven pregnant women carrying 72 fetuses (5 twins) whose fetal umbilical artery flow S/D ratios were more than the 95(th) percentage were divided into study and control groups. In study group, 35 women carrying 38 fetuses were treated with heparin at a dose of 6250 U or 12,500 U + 5% glucose 500 ml intravenously per day for a mean of (3.7 +/- 2.1) days, ranging from 1 to 10 days. In control group, another 32 women with 34 fetuses were treated regularly with dextran-40,500 ml and 10% glucose 500 ml + rooted salvia 30 ml; and 10% glucose 500 ml + 654-II 20 mg for a mean of (6.8 +/- 2.8) days, ranging from 3 to 14 days. After treatment the S/D ratios were re-examined, and compared between two groups.


RESULTS
The mean of decreased S/D ratios per day in heparin group and control group was 0.37 (t = 3.620, P < 0.01) and 0.135 (t = 3.061, P < 0.01), respectively. There was significant deference between two groups (t = 1.998, P < 0.05). The treatment time was significantly shorter in heparin group than in the control (t = 3.435, P < 0.01). The effective rate was significantly higher in heparin group than in the control (chi(2) = 10.636, P < 0.01). In the control group, there were 10 cases with S/D ratio increasing continuously. Two of them died of S/D ratio infinity. None of the study group died.


CONCLUSIONS
Heparin can significantly decrease the high S/D ratios of umbilical artery flow velocity waveforms at second trimester of pregnancy. It is effective for improving fetal outcomes.