Fetal echocardiography (real-time and M-mode) was used to evaluate a fetus at 20 weeks of gestation because intermittent bradycardia had been auscultated at 14 weeks of gestation. Real-time examination of the four-chamber view suggested ventricular disproportion with the left ventricle larger than the right, absence of the tricuspid valve, atrial and ventricular septal defects, and normal pulmonic and aortic outflow tracts. M-mode quantitation demonstrated a dilated left ventricle, small right ventricle, dilated mitral valve, hypertrophy of the left ventricular wall, and normal outflow tract dimensions. Following the diagnosis of tricuspid atresia (type Ic), genetic amniocentesis was performed (46,XX). Intrauterine death occurred during the 28th week of gestation. Autopsy confirmed the echocardiographic findings. Indexing Words: Fetal echocardiography * "ricuspid atresia * Ventricular disproportion * Ultrasound With the introduction of diagnostic ultrasound, it is now possible to evaluate the human fetus and diagnose anomalies of the central nervous, musculoskeletal, genitourinary, gastrointestinal, and cardiovascular systems. 1-3 Because of its complexity and the myriad anomalies that can occur, the cardiovascular system is the most difficult for the fetal sonographer to examine. However, if one uses a systematic approach for imaging the fetal heart, a number of anomalies can be diagnosed in Tricuspid atresia, which occurs in 3% of congenital heart anomalies seen in postmortem studies, is characterized by the following defects: (1) atresia of the tricuspid orifice, (2) interatrial communication, (3) dilated lefi ventricular chamber with wall hypertrophy, (4) dilated mitral valve, and (5) a small right ventricular ~h a m b e r . ~ Tricuspid atresia can be further subclassified by the presence or absence of a ventricular septal defect u t e r ~. ~~