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Placenta | Placental chorangiomas

Placental chorangiomas are growths that are benign (non-cancerous) masses of placental tissue and blood vessels. Very large chorangiomas 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, fetal heart failure may develop.

Essential Information

  • A placental chorangioma is a benign tumour located in the placenta.
  • Large placental chorangiomas may “steal” blood from the fetal blood circulation and the fetal heart may have to pump harder to allow blood to reach the fetal circulation, and fetal heart failure may develop.
  • Heart failure in the fetus may present as “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 placental chorangioma is a rare, benign tumour of the placenta, which may grow to become very large.

Placental chorangiomas are usually diagnosed on a routine ultrasound.

If they are very large (≥ 7cm), placental chorangiomas may 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 fetal heart failure may develop. This can be diagnosed by a focused ultrasound (a fetal echocardiogram). It 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.

Placental chorangiomas must be monitored closely with ultrasound to ensure that they are not enlarging rapidly and that there is normal fetal growth and wellbeing. Mothers must also be monitored closely because, rarely, the lesions 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.

Fetal Therapy

In most cases, fetal vascular tumours will be monitored with ultrasound only and no intervention will be necessary. In severe cases, fetal surgery may be necessary to interrupt the blood flow to or within the tumour, causing it to shrink. Either radio frequency ablation (RFA) or interstitial laser may be used to do this. 

Referral Information


  • Large placental chorangiomas (>5 cm diameter) or those resulting in cardiac failure and hydrops.

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. 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.