Pathologic findings in pregnancies with unexplained increases in midtrimester maternal serum human chorionic gonadotropin levels

Second trimester maternal serum human chorionic gonadotropin (MShCG) levels are commonly obtained as part of cc screening protocol for chromosomal ano malies. Approximately 4% to 6% of patients have elevated hCG levels for ges tational age, and this test has been reported to identify a group at risk f or pregnancy complications. We ascertained 24 patients with unexplained ele vated MShCG levels and available placental pathology among 5,790 deliveries during a 58-week period and compared them with 48 controls with normal MSh CG levels delivering during the same period. Cases had a higher prevalence of preeclampsia, intrauterine growth retardation, and preterm delivery. Pat hology in cases included more large-for-gestational-age placentas, fewer sm all-for-gestational-age placentas, lower mean fetoplacental weight ratios, more decidual plasma cell infiltrates, and more retroplacental hematomas. O ther more frequent abnormalities that did not reach statistical significanc e included abnormal placental shape and chronic villitis. Maternal and feta l vascular abnormalities were similar in both groups. Morphometric analysis were performed on hCG-immunostained sections from placentas at 17, 21, 36 and 41 weeks' gestation. Patients with elevated MShCG showed an increased v olume of hCG-positive trophoblast per unit surface area and increased inten sity of hCG immunoreactivity within individual terminal villous units.