(373) Impact of Maternal Obesity on Ultrasound Clearance Rates of Fetal Cardiac and Spine Anatomy

Objective:
Rates of maternal obesity has risen substantially, presenting diagnostic challenges and increased risks of fetal anomalies. Cardiac and neural tube defects are frequently limited by poor acoustic windows in patients with elevated body mass index (BMI). This study aimed to evaluate the impact of maternal obesity (BMI >30) on completion rates of key cardiac and spine views before the implementation of the AIUM first-trimester detailed protocol.

Study Design:
This IRB-approved retrospective cohort study included singleton pregnancies with maternal BMI >30 undergoing anatomy ultrasound between 18 to 22+6 weeks at Albany Medical Center and two affiliated sites from 06/01/23 to 12/01/23. Patients were stratified by BMI into 3 groups: 30.0–39.9, 40.0–49.9, and ≥50.0. Exclusion criteria were multifetal gestation, known fetal anomalies, BMI < 30.0, or no follow-up imaging. Ultrasounds were performed by registered sonographers supervised by five board-certified maternal-fetal medicine faculty. Cardiac views were considered complete if four-chamber and both outflow tracts were visualized. Craniospinal anatomy was complete if the cranium, ventricles, cerebellum, cisterna magna, and full spine were seen.

Results:
Multivariable logistic regression showed patients BMI >40 had significantly lower cardiac anatomy visualization rates, ranging from 38–70%, with the four-chamber and outflow tract views most frequently incomplete (Figure 1). Spine visualization was also limited, with lumbar and sacral segments most commonly affected. Patients with BMI 30–39.9 served as the reference group, and those with BMI ≥40 had up to a 5.17-fold increased odds of incomplete spine imaging (Figure 2). Among those with BMI ≥50, complete visualization occurred in only 28% of cases initially improving to 76% with multiple scans.

Conclusion:
Maternal obesity limits cardiac and spine visualization on ultrasound, particularly BMI ≥40. Early and repeat imaging improve overall clearance rates, but limitations persist. These findings support the integration of standardized protocols and early detailed ultrasound in high-BMI patients