To establish a method of prenatal ultrasound diagnosis of fetal unroofed coronary sinus (UCS).

A method for observing sections of the coronary sinus was established by using a fetal cardiac anatomy database of persistent left superior vena cava (PLSVC) with coronary sinus dilation. For fetuses with suspected UCS in Peking University People's Hospital from January 2018 to March 2025, the established method of displaying coronary sinus sections was utilized for diagnosis, and the efficacy of the prenatal ultrasound diagnosis method for UCS was analyzed.

The classical coronary sinus sections included: (1) long-axis view: the heart transverse section along the coronary sinus long axis could view its full length; (2) four-chamber view: the short axis of the coronary sinus is displayed at the left atrioventricular groove; (3) parasagittal view: the short axis of the coronary sinus is visualized through the left atrioventricular groove; and (4) trans-biatrial coronal view: the long axis of the coronary sinus is demonstrated. A diagnosis of UCS can be made by the presence of discontinuity of coronary sinus sinus wall on any of the above sections, and abnormal blood flow on color Doppler flow imaging can further support the diagnosis. Using this standardized prenatal ultrasound approach, 10 fetuses with UCS were successfully diagnosed.

By reconstructing the existing anatomical data, sections of the fetal coronary sinus were established, which were used to guide prenatal ultrasound doctor for the screening of UCS, thereby improving the accuracy and efficiency of prenatal diagnosis of UCS.