Up to 25 percent of women who have two or more spontaneous miscarriages have antiphospholipid syndrome (APS), according to the web site of the APS Foundation of America (APSFA).
Other names for this condition are antiphospholipid antibody syndrome and Hughes syndrome. It is an autoimmune condition that affects women more often than men. APSFA reports estimates that 75 to 90 percent of APS cases are women.
“Because APS patients can present very differently with a diverse range of clinical symptoms, it remains a challenge for clinicians to recognize the underlying disease,” wrote Katrien Devreese of Ghent University Hospital in Belgium and her colleague Marc F. Hoylaerts in a review article published in the journal Clinical Chemistry.
The characteristic features of APS are vascular thrombosis (blood clots) and complications of pregnancy, including severe preeclampsia and fetal loss. The blood clots can cause stroke, heart attack, gangrene, and other organ damage.
Historically, APS was first recognized in the 1950s. In 1999, a set of diagnostic criteria called the Sapporo criteria was published. This standard made a distinction between primary and secondary APS.
Many patients with APS also have systemic lupus erythematosus or another autoimmune disease, and these patients were diagnosed with secondary APS. Primary APS was the term for the diagnosis in the absence of other autoimmune conditions.
The Sydney criteria published in 2006 omitted the distinction between primary and secondary APS. Devreese explained that when the patient has both APS and lupus, for example, it is not clear whether lupus is the primary disease and APS is secondary, or the two conditions have a different relationship.
Blood tests for clotting and for autoantibodies are important for the diagnosis. The antiphospholipid antibodies are also found in patients with other autoimmune diseases, in those receiving drugs such as procainamide and chlorpromazine, in children and adults with infections, in cancer patients, and sometimes in healthy individuals. Thus, both the Sapporo criteria and the Sydney criteria require multiple positive tests for the diagnosis of APS.