Severe preeclampsia with and without HELLP differ with regard to placental pathology

The aim of the present study was to evaluate the histopathology in placentas from patients with severe preeclampsia with and without hemolysis, elevated liver enzymes, and low platelets (HELLP) syndrome. An additional aim was to compare the prevalence of infants born small for gestational age in the 2 groups. The study is retrospective and includes 178 women who have been diagnosed at the Karolinska University Hospital Huddinge or at the Free University Medical Center between 2000 and 2005 with severe preeclampsia. A total of 96 women had severe preeclampsia without signs of HELLP (preeclampsia group), whereas 82 fulfilled the criteria for having HELLP syndrome (HELLP group). Infarction (P=0.014), intervillous thrombosis (P<0.001), and abruption (P=0.002) were more common in the preeclampsia group than in the HELLP group. There was no statistically significant difference in the frequency of accelerated villous maturation (P=0.61), decidual arteriopathy (P=0.27), or chorioamnionitis (P=0.61). Furthermore, there was a higher mean placental weight, adjusted for gestational age, in the Swedish HELLP material than in the preeclampsia group (P<0.001). Finally, mothers in the preeclampsia group gave birth significantly more often to small for gestational age babies than mothers suffering from HELLP syndrome (P<0.001). The histopathologic profile and the range of placental lesions were partly different in the preeclampsia and HELLP patients. Considering the central role that placenta seems to have in preeclampsia, the present result might suggest that different underlying pathogenetic mechanisms and courses can be in play in patients with preeclampsia and HELLP syndrome.