Fetal inflammatory response is often present at early stages of intra-amniotic infection, and its distribution along cord is variable.

This study investigates the hypotheses that (1) the fetal inflammatory response to intra-amniotic infection can occur in early stages of maternal inflammatory response and (2) a difference in early cord inflammation exists at different sites in the cord. Placentas accessioned in our department over a 4-year period with a differential in umbilical vessel inflammation between proximal and distal sections were evaluated for cord inflammation using a 0 to 4 graded scale. Cases were also evaluated for acute chorionic vasculitis and extent of maternal inflammatory response. Of 5566 placentas, 1004 (18%) had some degree of cord inflammation; 120 (12%) had a differential in inflammation between the 2 cord sites. Greater cord inflammation was divided almost equally between proximal (59) and distal (61) sections. Twenty-two cases had 1 or both arteries involved in 1 cord section only. The proximal section had the greater degree of inflammation in 21 (95%) of these cases. Early or no maternal inflammatory response was seen in 63 of 120 cases (52%). Acute chorionic vasculitis was identified in 57 of 106 cases (54%) with at least 2 chorionic vessels present. Fetal inflammatory response can be seen in early amniotic infection, occasionally without finding maternal inflammatory response. The absence of differences in cord vein inflammation depending on cord site and the finding that arteritis occurs close to the placental cord insertion site suggest that cord vessel blood flow dynamics play a role in neutrophil margination. At least 2 cord sections representing proximal and distal sites are recommended to exclude fetal inflammatory response.