Removal of the coccyx may include additional complications. In one review of 25 patients, however, the most frequent complication was an unsatisfactory appearance of the surgical scar. Late effects
Late effects are of two kinds:  consequences of the tumor itself, and consequences of surgery and other treatments for the tumor.Complications of not removing the coccyx may include both recurrence of the teratoma and metastatic cancer. Late malignancies usually involve incomplete excision of the coccyx and are adenocarcinoma.Although functional disability in survivors is common, a small comparative study found a nonsignificant difference between SCT survivors and a matched control group. In rare cases, pelvic scarring may necessitate that a pregnant woman who is a SCT survivor deliver her baby by Cesarean section. Cause
SCT is seen in 1 in every 35,000 live births, and is the most common tumor presenting in newborn humans. Most SCTs are found in babies and children, but SCTs have been reported in adults and the increasingly routine use of prenatal ultrasound exams has dramatically increased the number of diagnosed SCTs presenting in fetuses. Like other teratomas, an SCT can grow very large. Unlike other teratomas, an SCT sometimes grows larger than the rest of the fetus. Sacrococcygeal teratomas are the most common type of germ cell tumors (both benign and malignant) diagnosed in neonates, infants, and children younger than 4 years.
Other tumors can occur in the sacrococcygeal and/or presacral regions and hence must be ruled out to obtain a differential diagnosis. These include extraspinal ependymoma, ependymoblastoma, neuroblastoma and rhabdomyosarcoma. Smaller SCTs with an external component, seen in prenatal ultrasounds or at birth, often are mistaken for spina bifida. Cystic SCT and terminal myelocystocele are especially difficult to distinguish;  for more accurate diagnosis, MRI has been recommended. Treatment
The preferred first treatment for SCT is complete surgical removal (i.e., complete resection). The preferred approach to a small SCT is through the perineum; a large SCT may require an additional approach through the abdomen. Resection should include the coccyx and may also include portions of the sacrum. The surgery should include reattachment of the small muscles and ligaments formerly attached to the coccyx, in effect reconstructing the posterior perineum. If not, there is an increased risk of perineal hernia later in life. SCTs are classified morphologically according to their relative extent outside and inside the body:

Altman type I — entirely outside, sometimes attached to the body only by a narrow stalk
Altman type II — mostly outside
Altman type III — mostly inside
Altman type IV — entirely inside;  this is also known as a presacral teratoma or retrorectal teratomaThe Altman type is significant in the contexts of management of labor and delivery, surgical approach, and complications of SCT. Serial ultrasound and MRI monitoring of SCTs in fetuses in utero has demonstrated that the Altman type can change over time.