Low molecular weight heparin in pregnancies with persistently abnormal uterine artery Doppler, does it make a difference? A prospective proof of concept study

Abstract

Introduction: Trophoblastic invasion converts the uteroplacental circulation into a low resistance, high capacitance system. Defective invasion causes hypoperfusion and pregnancy complications. Early pregnancy uterine artery Doppler demonstrates low end-diastolic velocities. Its PI and RI decrease with increasing gestation. Aim of the study: Examing the effect of adding low molecular weight heparin (LMWH) to low-dose aspirin on persistent high uterine artery Doppler indices and its impact on fetal growth and pregnancy outcome. Patients and methods: After approval of Alexandria university ethics committee, pregnant cases with positive past history of placental vascular complication including; placental abruption, preeclampsia, small-for-gestational age (SGA) pregnancies and fetal growth restriction were recruited. All selected patients were in good general health without previous history of Diabetes Mellitus or thyroid disorders or cardiac diseases. Patients with thrombocytopenia, bleeding tendencies, multiple pregnancies, and pregnancies complicated by fetal or neonatal chromosomal or structural anomalies were excluded from the study. Eligible patients were 412, all were subjected to uterine artery Doppler measurement in the first trimester. 148 cases had high uterine artery Doppler PI, they were given low dose aspirin and were re-evaluated at 22-24 weeks gestation. 58 cases had persistently high uterine artery Doppler PI, they were allocated into 2 groups each of 29 cases; Group A LMWH with aspirin. Group B only low dose aspirin. 50 pregnants with normal uterine artery Doppler PI from the start were taken as a control group. All participants were followed up at 28-30 and 34-36 weeks. Primary outcome: Normal uterine, umbilical and cerebral artery Doppler measurements after LMWH. Secondary outcome: Prevention of pregnancy complications and neonatal complications. Results: Uterine and umbilical artery Doppler and amount of liquor significantly improved. Conclusion: LMWH influenced uterine artery and umbilical Doppler measurements and amount of liquor and reduced the risk of neonatal hypoxic ischaemic encephalopathy.