Booking ultrasound examinations performed by obstetric senior house officers--time to reevaluate?

We evaluated the proficiency of obstetrics senior house officers, not formally trained in ultrasonography, in assessing fetal viability, the number of fetuses and gestational age. Of 366 women who had an ultrasound examination at the first antenatal visit, 7 (2.1%) had nonviable pregnancies and 7 pairs of twins were correctly identified. Of these women, 329 had a detailed anomaly scan at 18-20 weeks. No anomalies were detected at either scan. Of the booking scans performed by the senior house officers, 89.4% correctly assessed the gestational age of the pregnancy when compared to the anomaly scan (+/- 1 week). One in 10 of the scans performed by the senior house officers was inaccurate. This is important particularly when being used for risk assessment in serum screening for Down syndrome. At present the early ultrasound scan should be performed by more formally trained personnel.