Chorionic villous vascularization related to phenotype and genotype in first trimester miscarriages in a recurrent pregnancy loss cohort.

STUDY QUESTION Is there an association between chorionic villous vascularization, ultrasound findings and corresponding chromosome results in early miscarriage specimens from a cohort of recurrent pregnancy loss patients? SUMMARY ANSWER We did not find a significant difference in vascularization scores of chorionic villi between embryonic, yolk sac or empty sac miscarriages, or between euploid and noneuploid miscarriages. WHAT IS KNOWN ALREADY At least half of first trimester miscarriages are due to embryopathogenesis associated with chromosome errors and/or major congenital anomalies, resulting in an empty sac, a yolk sac or an embryonic miscarriage. Absent and decreased chorionic villous vascularization is usually present in these pregnancies. STUDY DESIGN, SIZE, DURATION For this retrospective study, 60 hematoxylin and eosin slides of miscarriage tissue of less than 10 weeks gestational age were collected from an academic institution. All patients were seen in consultation between July 2004 and October 2009. PARTICIPANTS, SETTING, METHODS Chorionic villous vascularization was determined using a previously published classification. The results were validated and compared with the ultrasound findings and corresponding chromosome results. MAIN RESULTS AND THE ROLE OF CHANCE There were 53 embryonic miscarriages, 5 yolk sac miscarriages and 2 empty sac miscarriages. Chromosome results were obtained in 59 of the 60 miscarriages; 37.3% were euploid and 62.7% were noneuploid. Validation of the vascularization score between observers was reasonable to good (Kappa 0.47-0.76), and 59% of the cases were classified as avascular. The vascularization score did not differ between euploid or noneuploid miscarriages, or between embryonic, yolk sac or empty sac miscarriages. Avascular villi were seen more frequently in miscarriages trisomic for chromosome 16, when compared with miscarriages with other trisomies (6 out of 7 versus 8 out of 22, P = 0.04). LIMITATIONS, REASONS FOR CAUTION Unfortunately, the number of samples in the study was limited. WIDER IMPLICATIONS OF THE FINDINGS Avascular villi may indicate abnormal early placentation as a part of embryopathogenesis. Further study is warranted to determine whether a genetic cause can be found to explain these results.