Intra-abdominal sacrococcygeal mature teratoma or fetus in fetu in a third-trimester fetus.

This case report describes a fetus with a large intra-abdominal, complex, vascular mass, displacing the normal intra-abdominal organs due to its large size. Extension to the presacral area was also identified, facilitating the diagnosis of a sacrococcygeal teratoma. Because of its highly mature nature, this was considered a fetus in fetu which was totally intra-abdominal.