In Search of Placenta and Umbilical Cord Risk Factors for Fetomaternal Hemorrhage: A Case-Control Study [18O

Abstract

INTRODUCTION: Fetomaternal hemorrhage (FMH) is an obstetric complication associated with adverse fetal and neonatal outcomes. Few reliable risk factors other than maternal trauma have been identified. Previous research has suggested an association between potentially obstructive umbilical cord abnormalities and FMH. METHODS: We conducted an IRB-approved case-control study within Kaiser Permanente Northern California between January 2008 and December 2017 to investigate whether cord abnormalities were associated with FMH. Cases were defined by adverse fetal or neonatal outcomes related to hypovolemia in the setting of a positive maternal flow cytometry for fetal hemoglobin. Controls were selected based on a negative flow result at time of delivery and available placental pathology report for review, matched to gestational age and year of delivery of cases. Delivery records and pathology reports were analyzed for 56 cases and 132 controls. RESULTS: There was at least one cord abnormality for 23.2% of cases and 25.8% of controls (P=.71). There were no significant differences between the two groups in placental weight percentile, cord length, or cord diameter. Marginal and velamentous cord insertion occurred slightly more frequently in controls compared to cases. Cord hypercoiling was found in 7.1% of cases vs 5.3% of controls (P=.74). CONCLUSION: We did not identify gross placental or cord characteristics associated with FMH. However, case numbers were too small for statistical significance and our study was limited to placentas sent to pathology, which may have biased our control group towards cord lesions. Further research is required to identify whether an association exists between cord abnormalities and FMH.