Prenatal Echocardiographic Diagnosis of Transposition of the Great Arteries: Challenges and Pitfalls

Abstract

Transposition of the great arteries (TGA) is one of the most common cyanotic congenital heart defects and is a leading cause of neonatal mortality when unrecognized before birth. Despite improvements in obstetric ultrasound screening, prenatal detection rates for TGA remain lower than for many other major congenital heart defects, largely because the four-chamber cardiac view is typically normal in this lesion. We report the case of a 23 years old primi-gravida, referred for a routine second-trimester anomaly scan. She has no significant history of any previous diseases. Her routine ante-natal investigation reports were normal. She was in regular follow up with her obstetrician. The Ultrasonogram revealed about 25 weeks of single live intrauterine pregnancy, which corresponded with her 1st day of last menstrual report. Fetal cardiac activity was regular with active fetal movements. Placenta was poster-fundal with adequate amniotic fluid. There was no gross anomaly. However, detailed examination of the fetal heart revealed an abnormal three vessel-trachea view with no ‘V’ shaped crossing of great arteries. The pulmonary trunk was seen arising from left ventricle and the aorta from the right ventricle. Thus, ultrasound imaging led to a prenatal diagnosis of transposition of the great arteries (TGA). This case illustrates the key sonographic markers that allow diagnosis of TGA in utero. Prenatal recognition of TGA allows for planned, specialized perinatal management and is associated with reduced neonatal morbidity and mortality. BJusg. vol. 27, no. 1, June 2026, Page: 43-49