The impact of maternal obesity on completion of fetal anomaly screening

To examine the impact of maternal obesity on completion of fetal anomaly screening.

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/m2), overweight (25.00-29.99 kg/m2), obese class I (30-34.99 kg/m2), obese class II (35.00-39.99 kg/m2) and obese class III (≥40.00 kg/m2). A fetal anomaly imaging scoring system was developed from the National Health Service (NHS) Fetal Anomaly Screening Programme standard to evaluate scans.

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 four-chamber 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.

Maternal obesity has a significant impact on completion of fetal anomaly screening.