The systemic vascular resistance is increased as is the left ventricular stroke work index, leading to left ventricular strain. Consequently there may be left ventricular diastolic dysfunction with poor correlation between the central venous and pulmonary capillary wedge pressures. Up to one third of patients have thrombocytopaenia, and in severe cases platelet counts may fall rapidly. In addition, there appears to be a qualitative platelet dysfunction. Pulmonary oedema occurs most frequently after delivery.
Hepatic rupture is a rare, but often lethal, complication.
The prevalence of proteinuria indicates glomerular involvement, probably on a vascular basis. Oliguria is more commonly due to hypovolaemia and decreased renal blood flow rather than primary renal pathology. However, renal outcomes are generally good. The reduced placental perfusion results in a high prevalence of intra-uterine growth retardation. There is also a high incidence of abruptio placentae and preterm labour.