OBJECTIVE: Our purpose was to test the hypothesis that the HELLP (hemolysis, elevated liver enzymes, and low platelets) syndrome is the result of excessive vasoconstriction of the hepatic arterial circulation.STUDY DESIGN: Doppler ultrasonography was used to measure the pulsatility index of the common hepatic artery in 14 women with preeclampsia, 15 with preeclampsia complicated by HELLP syndrome, and 8 with HELLP syndrome but without proteinuria.