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Spine |Sacrococcygeal teratomas (SCT)

Fetal tumours such as sacrococcygeal teratomas (SCT) are growths that are usually benign (not-cancerous) masses of tissue and blood vessels. Very large tumours (≥7 cm diameter) may “steal” blood from the fetal circulation, resulting in the fetal heart having to work much harder to pump blood to the circulation. In these cases, heart failure may develop.

Essential Information

  • The most common fetal tumour is a sacrococcygeal teratomas (SCT), which develops before birth and grows from the coccyx (or tailbone) of a developing fetus.
  • SCTs are made up of many blood vessels, and, when they grow to be very large, may “steal” blood from the fetal blood circulation.
  • In very large SCTs (> 7 cm), the fetal heart may have to pump harder to allow blood to reach the fetal circulation, and heart failure may develop.
  • Heart failure in the fetus may present as a condition called “hydrops”, which is an accumulation of fluid under the fetal skin or in the fetal abdomen or chest. Fetuses with this condition are very sick and may not survive.


A SCT is a rare tumour, typically located at the fetal tailbone (or coccyx). Although SCTs are not cancerous, they are made up of many blood vessels and can grow to become very large. Females are four times more likely to be born with this condition than males.

SCTs are usually diagnosed on ultrasound, although the size and appearance of the masses varies significantly.

Large SCTs may “steal” or divert blood flow away from the fetus to facilitate their growth. In these cases, the fetal heart may compensate by pumping harder. Eventually, however, the heart will not be able to maintain this high output and heart failure may develop. This may be seen by studying the heart’s appearance on a focused ultrasound (a fetal echocardiogram) but may also become evident by the accumulation of fluid under the fetal skin or in the fetal abdomen or chest (a condition called “hydrops”). Fetuses with hydrops are very sick and may not survive.

Fetal vascular tumours such as SCTs must be monitored closely with ultrasound to ensure adequate fetal growth and wellbeing and to assess cardiac output. Mothers must also be monitored closely because, rarely, the tumours may cause the mother to develop a severe condition called “mirror syndrome”. In this case, mothers may develop high blood pressure, and fluid may accumulate, similar to the fetus, in their lungs.


In most cases, SCTs can be monitored with ultrasound only and no antenatal intervention will be necessary and they are removed after birth by the paediatric surgeons. Rarely, in severe cases, fetal surgery may be necessary. Intervention for fetal SCT’s include blockage of the blood supply feeding the tumor (by either radio frequency ablation (RFA) or interstitial laser) or open fetal surgery, as for fMMC repair, and debulking or excision of the SCT.  The optimal approach for each fetal SCT case will be decided in collaboration with the paediatric surgeons from SickKids hospital.


Referral Information


  • Large solid SCTs (> 5 cm) or those resulting in cardiac failure and hydrops prior to 30 weeks’ gestation.

Refer if signs of hydrops or high output cardiac failure present. The timing and type of procedure will be individualized based on patient presentation. Radio-frequency ablation (RFA) or interstitial laser procedures typically require 24 hours hospitalization, whereas open fetal surgery will require hospitalization for at least 1 week. In the presence of hydrops, monitoring for “mirror” syndrome is required. Post-operatively, out-of-province patients will be referred back to their local provider for ongoing antenatal care and delivery. Local patients will be followed and delivered at Mount Sinai Hospital.