Histologic features of placentas and abortion specimens from women with antiphospholipid and antiphospholipid-like syndromes

Antiphospholipid syndrome is characterized by recurrent pregnancy loss, thrombosis, and antiphospholipid antibodies. However, some women with clinical features of antiphospholipid syndrome test negative for antiphospholipid antibodies (“antiphospholipid-like syndrome”). Women with antiphospholipid and antiphospholipid-like syndromes have serum immunoglobulin G that harms murine pregnancy, suggesting that the mechanisms of fetal death may be similar in both groups. The objective of our study was to determine whether patients with antiphospholipid and antiphospholipid-like syndromes share pathophysiology by comparing the histology of gestational tissues from these groups. Placenta and abortion specimens were obtained from 44 pregnancies in 26 women with antiphospholipid syndrome and 37 pregnancies in 21 women with antiphospholipid-like syndrome. Of these, 16 pregnancies with antiphospholipid syndrome and 8 with antiphospholipid-like syndrome were treated with a variety of medications intended to improve pregnancy outcome. Placentas from 31 elective pregnancy terminations and 40 pregnancies complicated by idiopathic preterm delivery served as an additional control group. Twenty histologic parameters were systematically assessed by a single investigator who was blinded to the clinical status of the specimens. Histopathologic findings were compared among groups using multivariate logistic regression analysis. Antiphospholipid syndrome pregnancies included 15 spontaneous abortions, 13 fetal deaths, and 16 live births. Pregnancies in the antiphospholipid-like syndrome group resulted in 5 spontaneous abortions, 30 fetal deaths, and one live birth. Gestational tissues from antiphospholipid and antiphospholipid-like syndrome pregnancies were similar for every histologic feature tested. Decidua from women with both antiphospholipid and antiphospholipid-like syndromes had more necrosis, acute and chronic inflammation, and vascular thrombus compared to controls. Placental tissue from antiphospholipid and antiphospholipid-like syndrome pregnancies showed more infarction, intravascular fibrin deposition, syncytial knot formation, and fibrosis than controls. Histologic features were variable within groups. There were no histologic differences in tissues from live births and pregnancy losses, or in treated and untreated pregnancies. Placental histopathology is similar in antiphospholipid and antiphospholipid-like syndrome pregnancies, suggesting that these disorders may share pathophysiology. Histologic findings in women with APS are non-specific and may not differentiate between women with APS and APS-like syndromes.