To report the feasibility of identifying the foetal anatomy during the routine 11 to 13 + 6 weeks scan in the Ultrasound Unit at the Gutenberg Centre in Malaga, Spain.
We examined 990 patients who attended our Unit to carry out the ultrasound screening for chromosomal abnormalities and risk assessment for trisomy 21, and 652 were included for the analysis. We measured the nuchal translucency thickness and additional ultrasound markers during the 20 minutes allocated. In addition, we tried to visualise the main foetal anatomic structures, including the heart. The scans were done abdominally or by transvaginal approach, according to the preference of the operator.
The mean maternal body mass index was 23.9 and the mean gestation was 12 weeks; the mean crown rump length was 62.6 mm and the nuchal translucency thickness was above the 95th centile for gestation in 8.6%of the foetuses. Visualisation of the foetal anatomy was successful in 90%of cases, classified as normal or abnormal, in most of the structures. However, the heart and kidneys were more difficult to identify with confidence and success was achieved in 76%and 67%, respectively. The large majority (93%) of the scans were performed abdominally.
It is feasible to visualise the foetal anatomy in more than 90%of the cases during the routine first trimester scan. The heart and the kidneys remained the most difficult. We would like to stress the importance of the anatomical survey in the 11 to 13 + 6 weeks scan, in addition to the ultrasound markers assessment for the screening of chromosomal defects.