Figure 5b. Sacrococcygeal teratoma with developing cardiovascular failure. (a) US image of a fetal lower spine (Sp) shows a large complex mass with a substantial soft-tissue component (arrows). (b) Color Doppler US image demonstrates prominent feeding vessels (curved arrow) supplying the mass (straight arrow). (c) On a coronal US image of the fetal abdomen, the inferior vena cava (white arrow), compared with the aorta (black arrow, Ao), appears greatly dilated, a finding indicative of impending cardiovascular compromise. (d) Autopsy photograph shows obvious intratumoral hemorrhage within the teratoma.