Funisitis and chorionic vasculitis: relation to chorioamnionitis, timing and scoring.

Five hundred consecutive cases with histologic chorioamnionitis and umbilical cord inflammation were analyzed to develop a staging system for funisitis and to correlate stage of funisitis with stage of chorioamnionitis in order to estimate the timing of various stages of funisitis. Funisitis progresses through venous involvement (with or without Wharton's jelly inflammation) to arterial involvement without Wharton's jelly and then full involvement of all three vessels and surrounding Wharton's jelly. Arterial involvement and full funisitis are strongly associated with stage III/IV chorioamnionitis, and imply a significant time interval following the onset of amniotic cavity inflammation.