Clinical Implications of Distance to the Placental Edge in Patients With Marginal Cord Insertion [ID 1710]

INTRODUCTION: Marginal cord insertion (MCI) is defined as insertion of umbilical cord vessels at or within 2 cm of the placental edge. Limited data is available comparing outcomes at varying distances to the edge. We evaluated perinatal outcomes of patients with MCI less than 1.0 cm and between 1.0 and 2.0 cm from the edge. METHODS: A retrospective cohort study of all women with MCI diagnosed on second-trimester ultrasounds from July 2018 to February 2022 was performed. We compared outcomes between patients with normal cord insertion (NCI), insertion less than 1.0 cm, and insertion 1.0–2.0 cm from the edge. The primary outcome was small for gestational age (SGA) (birth weight less than 10th percentile). Secondary outcomes included preterm birth, low birth weight (less than 2,500 g), neonatal intensive care unit admission, and cesarean delivery for non-reassuring fetal status. RESULTS: One hundred ten patients were identified who met inclusion criteria (43 with insertion less than 1.0 cm, 67 with insertion 1.0–2.0 cm). An additional 234 patients were randomly selected with NCI. The baseline demographics were the same between groups. The group with insertion less than 1.0 cm had a higher rate of SGA (13.95% versus 2.99%; odds ratio [OR] 5.27; 95% CI, 1.01–27.45) compared to the group with insertion 1.0–2.0 cm. This significance persisted when comparing insertion less than 1.0 cm to the NCI group (13.95% versus 4.68%; OR 3.39; 95% CI, 1.18–9.75). There were no statistically significant differences for secondary outcomes. CONCLUSIONS/IMPLICATIONS: Although further studies with larger cohorts are needed, the diagnosis of MCI may warrant modification to less than 1 cm from the placenta edge as these fetuses may be at increased risk for SGA.