Intraobserver and interobserver variability for the histologic diagnosis of chorioamnionitis

Objectives The interobserver and intraobserver variability for the histopathologic diagnosis of chorioamnionitis was examined. Study design Two examiners independently reviewed archived slides from 250 placentas. They were blinded to the original diagnosis and details of the pregnancy. Definitions for two important diagnoses were made and a protocol for recording information trialed before the study. Slides were examined under conditions reflecting normal working practice. Results A high level of agreement for the diagnosis of chorioamnionitis and umbilical vessel vasculitis (κ range 0.78-0.81) between the examiners was found. Comparison of the agreement between each examiner and their original diagnosis was also excellent (κ range 0.90-0.91). Conclusion This study has audited the reliability of the diagnosis of chorioamnionitis, a common and important placental finding. The reproducible and reliable degree of agreement demonstrated permits further research to be undertaken relating this diagnosis to adverse postnatal outcomes.