What is involved in the evaluation of sacrococcygeal teratoma (SCT), and how is it treated?
SCTs are relatively rare tumors that arise at the base of the coccyx. The majority (≈75%) are benign. For US, the imaging is directed to determine:
- • The characteristics of the teratoma: cystic, solid, or mixed.
- • The size and volume of the mass. The volume to HC ratio can also be computed for follow-up purposes.
- • The type of the mass (the American Academy of Pediatrics classification):
- • Type I—external; may be pedunculated or have a small presacral component.
- • Type II—mostly external with a significant intrapelvic component.
- • Type III—mostly intrapelvic with abdominal extension, usually with a small external component.
- • Type IV—entirely internal with abdominal extension.
- • The vascular supply and venous drainage.
- • Displacement of pelvic structures.
- • Extension into the spinal canal.
- • Presence of associated hydronephrosis.
- • Proximity to the anus.
- • Presence of cardiac overload or hydrops.
These findings are important for postnatal surgical treatment, but early evidence of hydrops or other evidence of high output failure could prompt an open surgical approach unless the fetus is mature enough for early delivery. Development of maternal mirror syndrome, other fetal anomalies, multiple gestation, and placentomegaly (placental thickness at cord insertion is >3.5 to 4.0 cm) are all contraindications to open fetal surgery. US can help to plan delivery before high output failure ensues and to assist in postnatal surgical planning