Is chronic histiocytic intervillositis a severe placental disease? A case-control study

Introduction: Chronic histiocytic intervillositis (CHI) is a placental disease that has been associated with unfavorable obstetric outcomes in small, noncomparative series. The objective was to measure the excess risk of adverse obstetric outcomes associated with the discovery of CHI after birth. Methods: Retrospective single-center case-control study from 2000 through 2016. The case patients had a CHI diagnosis after a pathology analysis of the placenta. Two types of controls were defined for each case: low-risk control women were those who gave birth in our hospital immediately before each case patient, and the high-risk controls were the next women after each case for whom microscopic examination of the placenta was indicated. Results: We observed 111 cases of CHI during the study period. Compared with the 111 low-risk controls, the cases had a significantly higher frequency of late miscarriages (5.4 vs 0.0%, p < .03), small for gestational age (SGA) babies <3rd centile (70.4 vs 0.9%, p <.001, OR 140, 95% CI, 19.9-2800), and in utero deaths (35.1 vs 0.9%, p < .001, OR 59.6, 95% CI 8.5-1192), with significantly fewer children surviving to discharge (54.9 vs 99.1%, p < .001, OR 0.01, 95% CI, 0.00-0.08). All of these factors also differed significantly compared with the high-risk women (severe SGA: OR 3.7, 95% CI 1.9-7.0; in utero death: OR 4.1, 95% CI 1.9-8.7; children surviving to discharge: OR 0.27, 95% CI, 0.14-0.52). Discussion: Even compared with high-risk pregnancies, CHI is a severe placental disease associated with a substantial excess rate of late miscarriages, severe SGA and in utero death.