Subclinical chorioamnionitis as an etiologic factor in preterm deliveries

This study was performed to determine the possible relationship between histologic chorioamnionitis and genital tract cultures and their contribution to preterm delivery.

The study group consisted of 45 preterm and 37 term pregnancies. Cervico-vaginal cultures were obtained from all patients at admission and placentas were histopathologically evaluated and graded for inflammation of the chorial plate, amniochorionic membrane, umbilical cord and villi. Inflammation scores and presence of pathogenic bacteria were compared between the preterm and term patients.

Severe chorionic plate inflammation was present in 35.5% of 45 preterm deliveries as compared to 5.4% of 37 term deliveries. Amniochorionic-decidual inflammation was not present in 14 of the term deliveries (38%), mild (Grade 1--2) in 20 (54%) and severe (Grade 3--4) in 3 (8%) as compared to 14 (31%), 17 (38%), and 14 (31%) in the preterm group, respectively (P<0.05). Pathogenic bacteria were isolated from the lower genital tracts of all patients who had severe chorionic plate (CP) and/or chorioamnionic (CA) inflammation while this was true only in 37.5% of the patients with no or only mild chorionic plate inflammation (P<0.001 for CP, P<0.01 for CA).

Our results show that pathogenic bacterial colonisation of the cervicovaginal region is closely associated with placental inflammation, preterm labor and cervico-vaginal cultures which may be useful in determining the pregnancies at risk for preterm labor.