Prevalence of developmental and inflammatory lesions in nonmolar first-trimester spontaneous abortions.

The management of patients with first-trimester spontaneous abortions is handicapped by two problems: difficulty in recognizing conceptions that abort because of abnormal karyotypes and an incomplete understanding of what causes abortions with normal karyotypes. Our goals in this study were to define features useful in distinguishing normal from abnormal karyotype and to identify pathological processes contributing to abortions with a normal karyotype. The study population consisted of 668 well-characterized first-trimester spontaneous abortions derived from a larger study of 1,054 consecutively karyotyped spontaneous abortions. Clinical factors increased in specimens with normal karyotype were maternal age younger than 20 years (P=.0003) and autoimmune markers (P=.0474). Developmental features associated with abnormal karyotype were developmental stage less than 6 weeks (P=.0017), hydropic villi greater than 1 mm (P=.0004), and villi with two or more dysmorphic features (P=.0001). Developmental stage greater than 11.5 weeks was increased with normal karyotype (P=.0001). Histological features increased in specimens with a normal karyotype were chronic intervillositis (P=.0003), increased perivillous fibrin deposition with intermediate trophoblast (P=.0006), decidual plasma cells (P=.0040), deciduitis without plasma cells (P=.0660), and chronic villitis (P=.1581). Overall, 19% of samples with a normal karyotype versus 8% with abnormal karyotype had one or more of these findings (P < .0001). Autoimmune markers, chronic intervillositis, and increased perivillous fibrin with intermediate trophoblast all had positive predictive values greater than 85% for normal karyotype, whereas dysmorphic villi had a positive predictive value of 90% for abnormal karyotype. Patients with recurrent spontaneous abortion and normal karyotype were more likely to have one or more of the histological features listed above (31%) than patients with normal karyotype and no prior abortions (13%) and patients with recurrent abortion and abnormal karyotype (11%).