The impact of maternal obesity on completion of fetal anomaly screening

Objective: To examine the impact of maternal obesity on completion of fetal anomaly screening. Methods: A retrospective analysis of 500 anomaly scans (19 + 0-21 + 6 weeks) was included. Women were categorised according to the World Health Organisation (WHO) body mass index (BMI) classification: normal weight (18.50-24.99 kg/m(2)), overweight (25.00-29.99 kg/m(2)), obese class I (30-34.99 kg/m(2)), obese class II (35.00-39.99 kg/m(2)) and obese class III (>= 40.00 kg/m(2)). A fetal anomaly imaging scoring system was developed from the National Health Service (NHS) Fetal Anomaly Screening Programme standard to evaluate scans. Results: Image quality deteriorated as BMI increased and was significantly different across the BMI categories (P < 0.001). Performance was poorest in imaging of the fetal chest and was significantly different across BMI categories (P < 0.001). In obese class III, 33% of fourchamber cardiac views and 38% of outflow tract views were not obtained. In total, 119 women (23.6%) had an incomplete scan. In obese class III, 44.1% of scans were incomplete compared with 10.2% in the normal BMI category (P < 0.001). Of 117 women attending for repeat scans, 78.6% were complete, 11.1% were incomplete, 6.8% were advised to re-attend and 3.4% were referred to Fetal Medicine. Conclusion: Maternal obesity has a significant impact on completion of fetal anomaly screening.