Continuous-wave Doppler ultrasound and decreased amniotic fluid volume in pregnant women with intact or ruptured membranes. 
The cause(s) of decreased amniotic fluid in the absence of fetal anomalies and intrauterine growth retardation is not clear.  A prospective study was performed to evaluate umbilical and uterine artery Doppler velocimetric results in pregnancies complicated by decreased amniotic fluid.  Three medically high-risk groups were studied: women with (1) normal fluid and intact membranes, (2) decreased fluid and intact membranes, and (3) decreased fluid and ruptured membranes.  The decreased fluid/intact membranes group had a significantly increased incidence of abnormal uterine artery waveforms (diastolic notching or absence of end-diastolic velocity); however, uterine systolic/diastolic ratios were not significantly different.  The umbilical systolic/diastolic ratios were marginally higher in the intact membranes/decreased fluid group when compared with the ruptured membranes group.  This study suggests that problems with maternal blood supply to the placenta may be related to decreased amniotic fluid when membranes are intact.