TABLE 1.

Placental Diagnostic Categories and Corresponding Reported Diagnoses ^*

Placental categories	Reported diagnoses**
Histologic chorioamnionitis	Acute chorioamnionitis; acute subchorionitis; acute funisitis; acute villitis***; acute intervillositis***; acute intervillositis***
Chronic villitis	Chronic villitis; lymphoplasmacytic villitis
Maternal vascular malperfusion	Acute atherosis; decidual vasculopathy; decidual vascular thrombosis; fibrinoid changes/necrosis in decidual vessels; retroplacental hematoma; hypermature chorionic villi; intervillous thrombus; increased perivillous fibrin; accelerated villous maturation; infarction
Marginal (venous) abruption	Circummarginate/circumvallate placenta; marginal hematoma; marginal abruption with membranous hemosiderin; subchorionic hematoma
Umbilical cord (UC) obstruction	UC knot; UC thrombosis
Fetal vascular malperfusion	Avascular villi; stem villus thrombus; hemorrhagic endovasculitis; villous sclerosis; fetal vascular thrombosis; chorionic plate vascular thrombosis
Villous stromal-vascular abnormalities	Chorangioma/chorangiosis; hypomature villi (delayed maturation); increased Hofbauer cells
Miscellaneous findings	Meconium-laden macrophages; maternal floor infarction; unusual placental shape; UC insertion abnormalities

^*Framework for categories and diagnoses adapted from [15] Redline, RW. Am J Obstet Gynecol 2015 and [23] Redline, RW. Semin Perinatol 2015.

^**Both gross and microscopic diagnoses are included.

^***Most cases accompanied by some fetal membrane inflammation