Objectives: The objective of this study is to assess the quality of the views in the detailed anomaly ultrasound scan and examine the parameters that influence it.
Methods: Prospective study on singleton pregnancies examined at 20-24 weeks. Detailed views of all fetal organs were classified by the examiner as optimal/suboptimal. The duration of the examination was observed. Maternal characteristics, Fat Index (FI) (distance between the skin and the surface of the uterus), and fetal position were recorded.
Results: The study population consisted of 940 singleton pregnancies. Optimal visualization of all fetal structures was achieved in 66% of cases. Significant predictors were BMI, FI, and fetal position. None of the women with BMI ≥ 44 and none of the women with FI ≥ 60 mm had optimal visualization of all fetal structures. Median duration of the examination was 23 min. In 75% of cases, it was completed in the first attempt. Maternal weight, FI, and fetal position were the significant independent predictors of total examination time.
Conclusions: Optimal visualization of the fetal anatomy is restricted by maternal parameters and fetal position. The main limitation is accumulation of abdominal fat, usually but not always related to maternal obesity. The FI may be recorded as a measure of technical difficulty. The anomaly scan should be allocated at least 30 min scanning time.
Keywords: Anomaly ultrasound scan; fetal anatomy; quality assessment.