Basal Chronic Villitis and Disorders of the Placental Basal Plate: A Possible Immunological Link Between Hypertensive Disorders of Pregnancy and Morbidly Adherent Placenta.

Background: Hypertensive disorders of pregnancy (HDP) are a common cause for preterm delivery. Prior studies showed that chronic villitis (CV) is associated with intrauterine growth restriction, preeclampsia, intrauterine fetal death, and morbidly adherent placenta (MAP). The authors hypothesize that disorders of the placental basal plate, especially basal chronic villitis (BCV), are associated with HDP.

Methods: The laboratory information system was queried over 12 years to identify placentas with or without the clinical history of HDP and with or without multifocal/focal CV or BCV. As a control for tissue sampling, a similar search was performed over 5 years for placentas evaluated for MAP.

Results: Of 19,683 placentas identified, 14.8% had CV which was in 18.5% and 14.2% of placentas associated with or without HDP, respectively, a significant difference (P < .0001). BCV was present in 6.0% and 3.9% of placentas with or without HDP, respectively, also a significant difference (P < .0001). BCV was more likely than multifocal/focal CV to occur in HDP (32.4% vs 27.4%) when all cases of CV were analyzed (P = .025). Of 221 placentas with MAP, 64% had multifocal/focal CV and 36% had BCV.

Conclusions: BCV and CV are more common in placentas with HDP than in normotensive pregnancies. They are also seen in MAP, as supported by another recent study.