Sacrococcygeal Teratoma

Sacrococcygeal teratoma (SCT) is an unusual tumor, occurring in about 1 in 40,000 live births. The tumor is located at the base of the tailbone, called the coccyx. This birth defect is more common in girls than in males. Although the tumors can grow very large, they are usually not malignant (cancerous). They can usually be cured with surgery after birth, but occasionally cause trouble before birth.

SCT is typically discovered when a prenatal blood test at week 16 of pregnancy shows a high alpha fetoprotein (AFP) level, or when an ultrasound is performed because the uterus is abnormally large. The increased size of the uterus is often caused by extra amniotic fluid, called polyhydramnios.

Most newborns with SCT survive and do well with surgical removal of the tumor after birth. Malignant tumors are unusual. Rarely, fetuses with very large SCTs develop heart failure. These babies may be candidates for fetal intervention.

Sacrococcygeal teratomas are generally not cancerous, and most babies do well with surgical treatment after birth. Babies with small tumors that can be removed along with the coccyx bone after birth can be expected to live normal lives. However, they will need to be delivered in a hospital with pediatric surgeons and a specialized nursery.

Fetuses with larger tumors or tumors that go up inside the baby's abdomen will require more complex surgery after birth, but generally do well. Very large tumors, which can reach the size of the fetus, can pose a difficult problem both before and after birth.

We have found that SCTs that are largely cystic — meaning filled with fluid — generally don't cause a problem. However, SCTs that are made up of mostly solid tissue and have a lot of blood flow can have adverse effects. This is because the fetus's heart has to pump blood to circulate not only to its body, but also to all the blood vessels of the tumor, which can be as big as the fetus. In essence, the heart is performing twice its normal amount of work.

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SCT can be diagnosed with an ultrasound examination.

The severity of a sacrococcygeal teratoma is directly related to the size of the tumor and the amount of blood flow to it. Both the size and the blood flow can be accurately assessed with ultrasound and echocardiography.

Pregnancy Care and Planning Delivery

Because all sacrococcygeal teratomas must be surgically removed after birth, arrangements should be made for the infant to be born in a specialized hospital with pediatric surgery expertise.

Small or medium-sized tumors without excessive blood flow should be followed with regular ultrasounds to make sure the tumor doesn't grow and its blood flow doesn't increase.

Fetuses with large, mostly solid tumors need to be monitored frequently between 18 and 28 weeks of pregnancy for rapid growth of the tumor, the development of excessive blood flow to the tumor, and heart failure. A small number of these fetuses develop heart failure due to extremely high blood flow through the tumor. These fetuses may be candidates for fetal intervention.

Fetal Intervention

Fetal intervention is offered only if there is evidence of heart failure in the fetus. Heart failure is usually diagnosed by ultrasound.

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Reviewed by health care specialists at UCSF Benioff Children's Hospital.

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