Obstetric antiphospholipid syndrome: current uncertainties should guide our way.

The subject of obstetric antiphospholipid syndrome (APS) has been reviewed dozens of times, and there is little doubt that the international APS community has done well in bringing APS to the attention of clinicians around the world. However, the evolution of clinical practice, at least in the US, also has convinced us that our field would benefit from further clinical study. For example, the number of women diagnosed with 'APS', but who do not meet the revised Sapporo criteria, seems to have increased. It is now common practice for women with recurrent miscarriage or prior fetal death to be treated with heparin, even in the presence of indeterminate or low titer antiphospholipid antibody (aPL) levels and even after only one positive test. In part, this common practice derives from confusion on the part of many clinicians and patients regarding the diagnosis of APS as well as the clinical and laboratory criteria for the syndrome. In part, this derives from the common practice of so-called 'empiric treatment' in US reproductive medicine, often driven as much by patients as by clinicians. This brief commentary focuses on areas of uncertainty that we see as deserving of new or renewed study for the sake of improving our understanding of APS and best patient care.