• High power view of an umbilical vessel at site where fetal
neutrophils are migrating through the muscularis.
• Note the fetal neutrophils lining up at the periphery of the vascular lumen and interspersed in the muscularis.
•low virulence organisms , normal flora of vagina or
•obvious pathogens such as E.Coli, Mycoplasma, Ureaplasma
• bacteria ascending from vagina, breaching cervical defenses (mucus plug
• bacterial colonization of intrauterine space through intact or ruptured
• maternal and fetal acute inflammatory response
•clinically evident in 0.5-10% of pregnancies
•associated with preterm birth
•only 8-25% of mothers have symptoms such as fever, chills
•fetus may have decreased biophysical profile score or abnormal heart rate
•can lead to congenital pneumonia, gastroenteritis, menigitis, sepsis
although most infants do not have sepsis even with umbilical cord
|General Gross Description|
•membranes and chorionic plate appear cloudy and occasionally have a
yellow or green tint
•in severe cases the umbilical cord may have small yellow round lesions on
its surface which represent foci of PMN^s (small abscesses)
|General Micro Description|
•Chorioamnionitis: membranes (amnion and chorion + parietal decidua) show
neutrophilic infiltrate. PMN^s originate from maternal vessels in parietal
decidua and migrate into chorion and then amnion.
•Chorionitis: chorionic plate shows neutrophilic infiltrate. PMN^s orginate
from maternal intervillous space and migrate into subchorionic fibrin,
chorion itself and then amnion
•Funisitis: umbilical cord shows neutrophilic infiltrate. PMN^s orginate in
the fetal vessels of the umbilical cord and migrate sequentially through the
muscular layers of the vessel and then into the Wharton^s jelly.
•Chorionic vasculitis: chorionic vessels show neutrophils in wall. PMN^s
originate in the fetal vessels of the chorionic plate and migrate through
the walls of the fetal vessels toward the amniotic fluid
•Gibbs and Sweet "Maternal and Fetal Infections" (chapter 42) in Creasy
and Resnik, Maternal Fetal Medicine: Principles and Practices 3rd edition;
Philadelphia: WB Saunders, 1994, p644-646.