Estimation of Time of Fetal Death in the Second Trimester by Placental Histopathological Examination

Abstract

It has been suggested that certain placental histopathological changes may be useful in predicting the time of death in stillborn fetuses. We retrospectively evaluated 36 placentas from therapeutic terminations in which the time interval between fetal death and delivery was relatively short and well-documented to determine the earliest stillbirth-associated changes and the utility of placental examination in timing death in the second trimester. In each case, termination had been initiated by creating fetal asystole with intracardiac KCl injections. The gestational age ranged from 18–23 wk. The time from asystole to placental delivery range was 2.8–52.0 h. Placental groups were categorized by time intervals from asystole to delivery: I,<12h[ n = 4(11%)]; II, 12–24 h [ n = 15 (42%)]; III, 24–36 h [ n = 14 (39%)]; IV, > 36 h [ n = 3 (8%)]. Among eight histopathologic changes involving the umbilical cord or chorionic villi evaluated, only three were present in a significant number of cases and also appeared to be the result of stillbirth. Degeneration of cord vascular smooth muscle was present in 33% of umbilical cords in group I, but was seen in 100% of cords in groups II–IV; the extent of these changes increased significantly with increasing time intervals. Intravascular karyorrhexis was present in villous blood vessels in 75, 73, 64, and 100%, respectively, for groups I–IV. Villous blood vessel luminal abnormalities were seen in 25, 7, 21, and 67%, respectively, for groups I–IV. These findings indicate that these are the earliest morphological changes in stillbirth in second trimester placentas, but they cannot be used to accurately predict time of death in the relatively short time intervals evaluated in this study.