(157) Accuracy of Fetal Anatomy Survey in Diagnosis of Marginal Cord Insertion: A Retrospective Case Study

Marginal cord insertion (MCI) is defined as the umbilical cord insertion within 2cm of the placental edge. Preeclampsia, placental abruption and low birth weight have historically been associated with MCI. While assessment of placental cord insertion is recommended during formal fetal anatomy survey, the accuracy of ultrasound detection in the second trimester has not been studied. This study was designed to assess the accuracy of ultrasound diagnosis of MCI at the time of midtrimester fetal anatomical survey, as compared to postnatal histological evaluation.

Study Design:

We conducted a retrospective study of all deliveries at our hospital from January 2021 to June 2024 in which MCI was diagnosed on fetal anatomy survey and examined the corresponding placental pathology reports. All anatomical surveys were performed in the second trimester. Maternal variables such as age, presence of prior Cesarean scar, and severe obesity (BMI >35) were collected, as well as fetal variables such as presence of multi-fetal gestation and placental location.

Results:

Among the 210 patients diagnosed with MCI on anatomy scan, only 45.2% were confirmed to have MCI on review of placental pathology. A false positive finding of MCI was more common in obese (BMI >35) patients and in multiple gestations.  Only placental location correlated significantly with sonographic accuracy of detection- with anterior placentation favoring correct diagnosis.

Conclusion:

MCI found at the time of midtrimester fetal anatomical survey is often not confirmed at postnatal histology.  Placental location at the time of exam modestly impacts accuracy of midtrimester MCI diagnosis.