A 28-year-old primigravida was referred at 25 weeks' gestation for fetal cardiac evaluation. The four-chamber view showed significant ventricular disproportion due to right heart dilatation and a dilated coronary sinus (Figure 1a). The post-left atrial (LA) space index was 0.43 and the LA posterior-space-to-diagonal ratio was 0.18, of which both were below their respective cut-offs Figure 1 Imaging in fetus with coronary sinus (CS) total anomalous pulmonary venous connection at 25 weeks' gestation. (a) Grayscale ultrasound image in four-chamber view, showing significant ventricular disproportion due to right heart dilatation and dilated CS. (b-d) Color Doppler (b,c) and four-dimensional spatiotemporal image correlation with HD-live color silhouette selective-volume rendering (d) of three-vessel-and-trachea view (b) and transverse plane at level of left brachiocephalic vein (LBCV) (c,d) were normal. (e,f) Grayscale (e) and color Doppler (f) examination of four-chamber view, showing anomalous direct drainage of all pulmonary veins (PV) into dilated CS without a connecting vein, resembling whale's tail. (g) Spectral Doppler waveform of PV showing normal triphasic pattern.