Measurements in First-Trimester Abortion Products: A Pathologic Study.

CONTEXT.— Related to the advances in prenatal diagnosis and the emergence of medically challenging situations, there has been an increased interest in conducting a pathologic study of first-trimester abortion products. OBJECTIVE.— To evaluate measurements across a large group of first-trimester spontaneous abortion specimens. Potential goals include a validation of prenatal embryo and gestational-sac measurements as a function of gestational age (GA). DESIGN.— A retrospective case study of first-trimester spontaneous abortions between June 2015 and April 2017 in Centro de Genética Clínica Embryo-Fetal Pathology Laboratory, Porto, Portugal. Considering the inclusion criteria, 585 complete gestational sacs, 182 embryos, and 116 umbilical cords were selected. We recorded the weight of the gestational sacs and embryos and measurements of gestational sacs, umbilical cords, and embryo crown-rump length. Models were computed using regression techniques. RESULTS.— Gestational-sac diameter percentiles 5, 25, 50, 75 and 95 were calculated according to GA, and at each 1-week interval the diameter increased an average of 3 mm. Umbilical cord length percentiles 5, 25, 50, 75 and 95 were calculated according to GA, and at each 1-week interval, the length increased an average of 1.35 mm. Embryo crown-rump length estimated mean ± SD values were GA 6 weeks, 5.3 ± 2.3 mm; GA 7 weeks, 9.4 ± 4.8 mm; GA 8 weeks, 13.7 ± 8.2 mm; GA 9 weeks, 20.8 ± 9.1 mm; GA 10 weeks, 22.6 ± 13.4 mm; GA 11 weeks, 29.4 ± 12.9 mm; and GA 12 weeks, 52 mm. CONCLUSIONS.— Pathologic measurements obtained should be compared to expected measurements and correlated with ultrasound findings, clinical information, and microscopic findings. Deviations from expected values could lead to an understanding of early pregnancy loss.