2 | MATERIALS AND METHODS
This retrospective study analysed two-dimensional ultrasound, colour Doppler and STIC images of CAT diagnosed using prenatal ultrasound at the Gansu Maternal and Child Health Hospital from June 2017 to June 2022. The age of the pregnant women was 17–37 years (average 27.34 ± 4.76 years) and the first detected gestational week was 13–37 weeks (average 23.92 ± 3.38 weeks). The exclusion criteria were incomplete ultrasound or clinical data and lost to follow-up.
The Voluson E8, E10 colour Doppler ultrasound diagnostic instrument (General Electric Co., Boston, MA, USA) and an abdominal volume probe at a frequency of 2.0–5.0 MHz were used for the ultrasound. Pregnant women were placed in the supine position, the main structures of the foetuses were examined, and related growth and development assessments were performed. Visceral locations were determined, beginning with the transverse section of the abdomen. The foetal heart mode was selected, and reserved sections were checked according to cardiac standards, including two-dimensional ultrasonography, colour Doppler and STIC volume images. The ventricular outflow tract section and the three-vessel tracheal section were mainly observed. A CAT was considered if the ventricular outflow tract view showed only one set of semilunar valves, only one thick arterial trunk emerged from the left or right ventricles, the normal order of the great arteries disappeared on the three-vessel tracheal view, or only a single arterial trunk and the superior vena cava were displayed. The woman was instructed to hold her breath, and the STIC condition was selected for volume data acquisition when the foetus was in a quiet state, and the connection between the left and right pulmonary arteries and the common arterial trunk was determined on the stereoscopic STIC images. The diagnosis was confirmed by two deputy chief physicians with prenatal diagnosis qualifications. The pregnancy outcomes were followed up in all cases.
The common arterial trunk was divided into 4 types using the Van Praagh classification based on the origin of the pulmonary artery:4 A1 type: the common pulmonary artery originated from the left wall of the PTA (Figures 1a, 1b); A2 type: the left and right pulmonary arteries originated from the posterior or both lateral walls of the PTA, respectively (Figures 2a, 2b); A3 type: pulmonary artery originated from a single trunk and the ductus arteriosus, or collaterals supplied the other lung (Figures 3a, 3b); type A4: persistent trunk with severed interrupted aortic arch (IAA).
SPSS 25.0 statistical software (SPSS Inc., Chicago, IL, USA) was used to analyse the data. Maternal age and the detected gestational age were normally distributed and expressed as mean ± standard deviation. The count data are expressed as frequencies and percentages, and the chi-square or Fisher’s exact test was used to compare the groups. All results are two-tailed, and P <0.05 was considered significant.