A tumor that develops from the tailbone of a fetus is known as sacrococcygeal teratoma.

What is sacrococcygeal teratoma?

Sacrococcygeal teratoma (SCT) occurs when a tumor forms from the tailbone (coccyx) of a baby before birth. Though rare, it is the most common congenital (present at birth) tumor, occurring in 1 in every 35,000 babies. It is more common in female babies than in male babies. Most cases of SCT are not cancerous at birth; however, cases of very large growths can be life-threatening if the condition is not treated.

Types of Sacrococcygeal Teratoma

The type of tumor that develops will vary depending on its location.

• Type 1: The tumor is almost completely outside of the body but attached to the tailbone.
• Type 2: The tumor is mostly outside of the body, but a small part of the tumor is growing inside the body.
• Type 3: The tumor is still partly external, but it is growing from the pelvis and expanding into the abdomen.
• Type 4: The tumor is completely inside the body.

These tumors may also vary in their appearance.

• Cystic: Appear as clusters of fluid-filled areas with only a few blood vessels present.
• Solid: Appear as dense tumors that contain many blood vessels.
• Mixed: Includes both cystic and solid tumors.

Sacrococcygeal Teratoma Causes

The causes of sacrococcygeal teratoma are not yet known. 

Sacrococcygeal Teratoma Symptoms

Symptoms in the fetus

Rarely, SCTs can lead to issues in the fetus’ kidneys or bladder by pressing on them, leading to enlargement or blockage.

A more dangerous symptom is the presence of hydrops, which is the accumulation of fluid in two or more compartments of the fetus’ body. When this happens, the fetus’ heart begins to work harder to support the rest of the body and the tumor. This process can lead to swelling and possible heart failure. Hydrops can be life-threatening to the fetus, especially in those under 30 weeks gestation.

Hydrops is more common in large solid SCTs.

Symptoms in the mother

Rarer cases of these complications can affect the mother. Mothers may develop symptoms similar to that of the fetus with hydrops, which is known as maternal mirror syndrome. The mother may also develop preeclampsia, protein in the urine, vomiting, fluid retention and swelling of the feet and hands. 

Additionally, the presence of hydrops in the fetus can lead to an enlarged uterus, due to the fetus’ increased fluid levels, which may lead to discomfort, breathing problems and early contractions.

Sacrococcygeal Teratoma Diagnosis

Early diagnosis of sacrococcygeal teratoma is important. SCT may be detected if the mother’s blood test shows high amounts of alpha fetoprotein or when a sonogram shows increased uterus size. Most SCTs are now discovered during a routine ultrasound. 

If SCT is suspected, the mother may require additional testing, such as:

• Anatomy ultrasound to confirm and evaluate the tumor
• Doppler ultrasound to measure blood flow to the tumor or other parts of the body
• MRI or low-dose CT for a more detailed image of the tumor and fetal anatomy
• Fetal echocardiogram to measure the fetus’ heart function
• Amniocentesis and chromosomal analysis to look for related genetic issues

Sacrococcygeal Teratoma Treatment

After a diagnosis of SCT, both mother and baby will be monitored for the duration of pregnancy through ultrasounds and echocardiograms to assess their condition and monitor for complications. SCT is usually treated by surgery once the baby is born. However, fetal treatment with medications and/or surgery may be recommended if hydrops is present. 

Surgery Before Birth

If the tumors lead to life-threatening issues such as fetal hydrops, a fetal surgery may be recommended. These options include:

Open-Fetal Surgery

During this surgery, the mother’s abdomen and uterus is opened to access the fetus and remove all or most of the SCT. The wound in the baby is closed, as well as the uterus, which is placed back in the abdomen with the incision in the mother repaired. The mother will recover in a few days from the procedure, and the pregnancy will continue to be monitored closely.

Laser ablation

During this surgery, a needle is inserted into the mother’s abdomen and uterus, as well as the fetus. A laser fiber is moved through the needle and directly into the tumor, where it removes the active blood vessels. This helps reduce the tumor’s blood flow and reduces stress on the fetus’ heart.

EXIT (ex utero intrapartum treatment)

During this procedure, the baby’s head is delivered while the upper part of the body remains attached to the placenta. This method allows the surgeon to remove the tumor before the delivery is complete.

Surgery After Birth

In most instances, surgery for the child can occur very shortly after birth. After delivery, the baby will be taken to the neonatal intensive care unit for a short time before undergoing surgery. During this procedure, the tailbone and the tumor growing from it are removed. For very large SCTs, pediatric plastic surgeons assist with closing the surgical wound to improve the cosmetic result.
Following surgery, the child is placed on their stomach for up to seven days to let the incision wounds heal. The child will also receive any needed pain medication through IV or by mouth.

Postnatal Care

Children with SCT will be closely monitored by their care team for the first several years of their lives in order to watch for potential regrowth of the tumor. 

Delivery Options with Sacrococcygeal Teratoma

Babies who have small tumors can usually be delivered vaginally.

If the tumor is large, a cesarean section may be recommended in order to prevent the tumor from bleeding out or bursting.

Outlook for Babies with Sacrococcygeal Teratoma

The outlook for babies with SCT varies depending on the size, location and type of tumor. The survival rate for babies with the condition remains high when there is no hydrops. Most babies usually develop normally, but they need to be monitored for tumor recurrence and any issues related to potty training between 3 and 5 years of age.