Comparison of placental pathology between severe preeclampsia and HELLP syndrome

This study was performed to evaluate and compare the placental pathology in patients with severe pre-eclampsia (PE) and HELLP syndrome. Moreover, neonatal birth weight was compared between the two groups.

This cross-sectional prospective study was conducted in Alzahra and Beheshti Hospitals (Isfahan, Iran) between 2007 and 2009. Placentas from 32 patients having severe pre-eclampsia without HELLP (referred to as preeclampsia group) and 25 patients having severe preeclampsia with HELLP syndrome (referred to as HELLP group) were evaluated. The studied parameters included placental weight, chorioamnionitis (either acute or chronic), retroplacental hematoma, placental infarction, intervillous thrombosis, and decidual arteriopathy. Birth weight adjusted for gestational age was also compared between the two groups.

We found statistically more significant frequency of retroplacental hematoma in the PE group compared to the HELLP group (P value 0.00). Despite the relatively high frequency of accelerated villous maturation and decidual arteriopathy in both groups, the difference between the two groups regarding these two parameters was not statistically significant. Other placental features did not show any significant difference between the two groups either. The frequency of small for gestational age births showed no statistically significant difference between the two groups.

Retroplacental hematoma was the only placental pathology that showed statistically significant different frequencies between the two groups. Although this may suggest different underlying pathogenetic mechanisms in these two conditions, further studies are needed to confirm this hypothesis.