Combined Immature Platelet Fraction and Schistocyte Count to Differentiate Pregnancy-Associated Thrombotic Thrombocytopenic Purpura from Severe Preeclampsia/Haemolysis, Elevated Liver Enzymes, and Low Platelet Syndrome (SPE/HELLP).

Abstract

The occurrence of thrombotic microangiopathy (TMA) in pregnancy is an unfortunate emergency condition. Proper diagnosis is mandatory which requires the consideration of two overlapping diagnoses: severe preeclampsia/haemolysis, elevated liver enzymes, and low platelet syndrome (SPE/HELLP) and thrombotic thrombocytopenic purpura (TTP). The long turn-around times of ADAMTS13 testing precludes the timely distinction between the two conditions. We aimed at evaluating schistocyte counts and immature platelet fraction (IPF%), as both increase in TMAs, to discriminate between TTP and SPE/HELLP of pregnancy. IPF% was measured using Sysmex XE-2100 automated hematology analyzer, and schistocyte counts were estimated microscopically as per the International Council for Standardization in Hematology-Schistocyte Working Group guidelines. The study included 30 pregnant patients with SPE/HELLP, 13 pregnant patients with TTP, and 30 women with normal pregnancy. The discrimination between the two patient categories was based on clinical judgment and TTP cases were identified using the PLASMIC score. TTP patients had higher values of IPF% than SPE/HELLP [19.5% (16.9-27.1) vs 13% (9.5-23.25); p < 0.001]; similar results were revealed regarding schistocyte counts [6.5% (3.9-8.6) vs 2.1% (1.6-3.5); p < 0.001]. IPF% and schistocyte counts were able to discriminate between TMA patients and normal pregnant women, and between and SPE/HELLP and TTP patients. Moreover, the discriminatory function of each was improved when the two parameters were used in combination. IPF% analysis should be used in conjunction with manual schistocyte counting in TMA cases to distinguish TTP pregnant patients from patientshaving SPE/HELLP.