Clinical Characteristics and Outcomes of Patients Diagnosed With Chronic Histiocytic Intervillositis [ID 1443]

INTRODUCTION: Chronic histiocytic intervillositis (CHI) is a placental lesion associated with an aberrant, noninfectious activation of the maternal immune response. This can result in an accumulation of macrophages within the intervillous space of the placenta and is associated with adverse outcomes. This study aimed to describe clinical characteristics and outcomes of patients diagnosed with CHI in pregnancy. METHODS: This retrospective study utilized data abstracted from electronic medical records at a single institution. Patients with at least one pregnancy diagnosed with CHI or related intervillositis disorder confirmed by placental histopathology reports were included. Patients with intervillositis with infectious origin were excluded. This study was IRB approved. RESULTS: Nineteen patients were included, with the majority being White (89.5%, n=17), with a median age of 27 years at the time of delivery. Ten (52.6%) patients had autoimmune disease, and 11 (57.9%) had hypertension. Among the 19 patients, there were 61 pregnancies. Nineteen (31.1%) were pregnancies with a CHI diagnosis (index pregnancy), and 47.5% (29/61) of pregnancies occurred after the CHI diagnosis. Of the subsequent pregnancies, 70% (7/10) were diagnosed with CHI based on placental pathology. Fifty-one (83.6%) pregnancies reported complications, in which 63.2% (12/19) were in index pregnancies, and 28.6% (6/21) were in subsequent pregnancies ( P =.021). Pregnancy loss occurred in 55% (11/20) of index pregnancies, and 40% (10/25) post-index pregnancies. CONCLUSIONS/IMPLICATIONS: There may be a potential connection between CHI and autoimmune-related diseases. There is a significant association between pregnancy complications and CHI diagnosis. Risk of pregnancy loss after CHI diagnosis is approximately 40%.