(Giannakopoulos, 2013). Testing for these other antibodies is not recommended (American College of Obstetricians and Gynecologists, 2017). However, some studies have evaluated these nonconventional antiphospholipid antibodies in women who clinically meet APS criteria but do not have the classic antibody proile. In one study, treatment of women with these nonconventional antibodies ofered some beneits, such as a lower pregnancy loss rate (Mekinian, 2016).
Clinical features shown in Table 59-5 provide indications for testing. By international consensus, APS is diagnosed based on laboratory and clinical criteria found in Table 18-5 (p. 353). First, one of two clinical criteria-which are vascular thrombosis or certain pregnancy morbidity-must be present. With laboratory criteria, elevated levels of LAC, ACA, and anti-3zglycoprotein I should be conirmed on two occasions 12 weeks apart. he diagnosis can be further stratified based on the number of these tests that are positive (Miyakis, 2006).
Tests for LAC are nonspeciic coagulation tests. he partial thromboplastin time is generally prolonged because the anticoagulant interferes with conversion of prothrombin to thrombin in vitro. Tests considered more speciic are the dilute Russell vper venom test and the platelet neutralization procedure. here is currently disagreement as to which of these two is best for screening. If either is positive, then identiication of LAC is conirmed.
Branch and Khamashta (2003) recommend conservative interpretation of results based on repeated tests from a reliable laboratory that are consistent with each clinical case. Only approximately 20 percent of patients with PS have a positive LAC assay alone. Thus, ACA enzyme-linked immunosorbent assay (ELISA) testing should also be performed. Eforts have been made to standardize ACA assays, however, these remain without international standards (Adams, 2013). For each APS test, interlaboratory variation can be large, and agreement between commercial kits is poor.
As noted, nonspecific low levels of antiphospholipid antibodies are identified in approximately 5 percent of normal adults (Branch, 2010). When Lockwood and coworkers (1989) irst studied 737 normal pregnant women, they reported that 0.3 percent had LAC and 2.2 percent had elevated concentrations of either IgM or IgG ACAs. Subsequent investigations confirmed this, and taken together, they totaled almost 4000 normal pregnancies with an average prevalence for antiphospholipid antibodies of 4.7 percent. This is similar to that for normal nonpregnant individuals (Harris, 1991 ; Yasuda, 1995).
In women with high ACA levels, and especially when AC is identiied, risks for decidual vasculopathy, placental infarction, fetal-growth restriction, early-onset preeclampsia, and recurrent fetal death are increased (Saccone, 2017). Some of these women, like those with SLE, also have a high incidence of venous and arterial thromboses, cerebral thrombosis, hemolytic anemia, thrombocytopenia, and pulmonary hypertension (American College of Obstetricians and Gynecologists, 2017; Clowse, 2008). In 191 LAC-negative women with APS, women with antibodies to cardiolipin and 32-glycoprotein I had signiicantly higher miscarriage rates than if either one alone was positive (Liu, 2013). Women with higher titers tend to have more adverse outcomes (Hadar, 2017).