Obstetric antiphospholipid syndrome: an update on pathophysiology and management

Antiphospholipid antibodies (aPLs) are acquired antibodies directed against negatively charged phospholipids, a group of inner and outer cell membrane antigens found in mammals. Obstetric antiphospholipid antibody syndrome (APS) is diagnosed in the presence of certain clinical features in conjunction with positive laboratory findings. Although obstetric APS was originally reported in association with slow progressive thrombosis and infarction in the placenta, it is most often associated with a poor obstetric outcome. In fact, obstetric APS is one of the most commonly identified causes of recurrent pregnancy loss (RPL). Thus obstetric APS is distinguished from APS in other organ systems where the most common manifestation is thrombosis. Several pathophysiological mechanisms of action of aPLs have been described. The most common histopathological finding in early pregnancy loss has been defective endovascular decidual trophoblastic invasion. Treatment with heparin and aspirin is emerging as the therapy of choice, with ∼75% of treated women with RPL and aPLs having a successful delivery compared with <50% without treatment. This review highlights the diagnostic challenges of obstetric APS, the obstetric complications associated with APS, proposed pathophysiological mechanisms of APS during pregnancy, and the management of women during and after pregnancy.