Placental histologic criteria for diagnosis of cord accident: sensitivity and specificity.

"Cord accident" (compromised umbilical blood flow) as a cause of stillbirth is underreported, mainly due to a lack of diagnostic criteria. Based on fetal vascular pathology in the placenta, we have previously established histologic criteria for the diagnosis of cord accident. In the current study, we set out to test the sensitivity and specificity of these criteria by reviewing an independent set of stillbirth cases. Placental slides from 26 cases (in which cord accident was deemed the cause of death) and 62 controls (in which the cause of death was anything other than cord accident) were reviewed. The following histologic changes were noted: (1) dilated fetal vessels, (2) thrombosis in fetal vessels, and (3) avascular or near-avascular chorionic villi. "Minimal" criteria were defined as the presence of dilated and thrombosed fetal vessels, while the additional presence of focal or regional avascular or near-avascular villi satisfied the complete criteria. Of the 62 stillbirth controls with cause of death other than cord accident, 13 (21%) met the minimal criteria (specificity 79%) and only 4 (6%) met the complete criteria for cord accident (specificity 94%). In contrast, of the 26 cases with a cause of death related to cord accident, 16 met the minimal criteria (sensitivity 62%) and 12 met the complete criteria (sensitivity 46%). These histologic criteria identify cases of cord accident as a cause of stillbirth with very high specificity. This study confirms the utility of these criteria for diagnosis of cord accident and further stresses placental examination in evaluation of stillbirths.