Sampling the Placental Insertion Site Improves Funisitis Sensitivity: Implications for Maternofetal Cross-Talk
AM VanSandt, TK Morgan. OHSU, Portland, OR
Background: Acute chorioamnionitis is a sensitive sign of intra-amnionic infection. Maternal neutrophils infiltrate the placental chorionic plate and membranes. In contrast, funisitis is a specific sign of infection, mediated by fetal neutrophils. We hypothesize that if maternal cytokine signaling plays a role in stimulating funisitis, the distal placental insertion site may be the most sensitive section to detect this fetal inflammatory response.
Design: We performed a prospective study of placentas collected at OHSU from October 2008 to October 2009 (n=509). The proximal fetal and distal placental insertion sections of the umbilical cord were sampled for histologic examination. Only singleton placentas were included and cases were excluded if the cord was not adequately sampled, the cord was detached, short (less than 10 cm), or abnormally inserted (eg, velamentous). Sections of the cord were scored for funisitis and arteritis. Sections of the placentas were scored for signs of infection, which required at least acute chorionitis (reported negative predictive value of 97%). All slides were reviewed by a placental pathologist (tkm) and pathology resident (avs). Their diagnoses were compared by kappa statistic to test agreement between pathologists and between the fetal and placental sections of the cord.
Results: The frequency of intra-amnionic infection in our cohort was approximately 35% (acute chorionitis 13% [n=67], chorioamnionitis 21% [n=109], necrotizing chorioamnionitis 1% [n=5]). Funisitis was seen in 14% of our cohort. We observed excellent diagnostic agreement between pathologists (kappa 0.63, p<0.0001), but only moderate agreement between the fetal and placental sides of the cord (kappa 0.46; TABLE). Using acute chorionitis as the gold standard for infection, the sensitivity of detecting funisitis at the placental side of the cord was 97% (95% CI, 90-99) and 65% at the fetal side (52-75).
|Proximal Funisitis (n=24)||Proximal Arteritis (n=23)||Proximal Negative (n=26)*|
|Distal Funisitis (n=38)||16||5||17|
|Distal Arteritis (n=33)||6||18||9|
|Distal Negative (n=2)||2||0||0|