The Use of a High Frequency Linear Transducer in the Assessment of Fetal Anatomy at the Routine 11 to 13 + 6-Week Scan among Chinese Population

Abstract

Objectives: To determine if the use of high frequency linear transducer (HFLT) in addition to conventional curvilinear transducer (CCT) aids assessment of fetal cardiac and non-cardiac anatomy in the first trimester. Methods: Transabdominal CCT (4 -8 MHz) followed by HFLT (9 MHz) was used to study prospectively the visualization rate of basic and optional anatomical structures according to international guidelines. McNemar and Chi-square test were used to compare correlated and independent proportions respectively. Postnatal outcomes were traced. Results: Comparing with CCT alone, additional use of HFLT did not improve the completion rate of basic anomaly screen (95.0% vs. 97.0%, p = 0.5) in the 101 women studied, but it improved the visualization rate of some optional structures including lens (57.4% vs. 73.3%), three-vessel view (3 VV) (17.8% vs. 48.5%), left ventricular outflow tract (17.8% vs. 51.5%), kidneys (8.9% vs. 47.5%), and umbilical artery (86.1% vs. 93.1%) (all p < 0.05). Favourable fetal position was associated with a better visualisation of four-chamber view and 3VV (p < 0.05). Conclusions: Our findings supported that the use of HFLT in addition to CCT does not improve the completion of basic anomaly screen, nor does it achieve a high visualisation rate of different cardiac views in the first trimester.