Histological chorioamnionitis on extremely-low-birth-weight infants. Incidence and perinatal outcome

Abstract

Objective: to determine the incidence of clinical and histological chorioamnionitis on extremely-low-birthweight infants and its correlation with perinatal outcome. Material and methods: a descriptive and prospective study was carried out between May 2004 and April 2005. All infants weighing between 500 to 1.000 g with histopathological study of the placenta were included. Results: a total of 52 infants fulfilled the inclusion criteria. Histological study of the placenta was done in 44 patients (84,6%). The average birth weight was 822,3 g (SD 127 g) and the mean gestational age was 26 weeks (SD 2 weeks). Preterm labor was recorded in 28 mothers (63,6%), 18 (40,9%) had preterm membrane rupture. Histological diagnosis of chorioamnionitis was done in 27 cases (61,4%), 12 (27,2%) a clinical diagnosis of chorioamnionitis had been previously done. In 13 of the 27 cases of histological chorioamnionitis no premature rupture of membranes was recorded. 75% (9) of the patients with clinical diagnosis had in the histological study chorioamnionitis with fetal response in the placenta. In 5 cases histological chorioamnionitis with fetal response was found in absence of clinical diagnosis. Early neonatal mortality was observed in 15 (34%) cases and mortality during hospitalization in 23 (52,2%). Neonatal sepsis was seen in 2 patients (4,5%); in 11 cases (25%) early clinical sepsis, all of them associated with histological chorioamnionitis (*p=0,02). In 5 cases necrotizing enterocolitis was observed (11.3%); intraventricular hemorrhage in 12 (27,2%), 7 with grades 3 to 4 (16.2%). And finally 9 had bronchopulmonary dyplasia, associated to histological chorioamnionitis with fetal response (*p=0,01). Conclusion: histological chorioamnionitis has a high incidence and in 44% of the cases it was possible to confirm that it preceded the rupture of the membranes. Corioamnionitis is usually often clinically silent and is diagnosed by the pathologist after birth. Clinical diagnosis of chorioamnionitis presents low sensitivity and high specificity in relation to histological chorioamnionitis. Clinical suspicion of ovular infection is highly suggestive of advanced infection with histological fetal response. Histological choriamnionitis is statistically associated with preterm labor and early clinical sepsis. Histological chorioamnionitis with fetal response is statistically associated with bronchopulmonary dysplasia and necrotizing enterocolitis.