Placental Chorioangioma

A placental chorioangioma is a benign vascular tumour of the placenta made of proliferating capillaries within chorionic villi. Small tumours cause no harm, but those above 4 to 5 cm can shunt blood, causing fetal anaemia, heart failure, hydrops, polyhydramnios, growth restriction and fetal death.

• Risk factors: multiple pregnancy, preeclampsia, maternal diabetes, female fetus, high altitude.
• Large tumours often lie near the cord insertion on the fetal surface.
• Associated with neonatal anaemia and low platelets.

Women with small tumours have no symptoms. Large tumours cause a uterus larger than dates from polyhydramnios, reduced fetal movements or signs of hydrops.

• Fundal height above dates.
• Raised maternal serum alpha fetoprotein in some.
• Differential diagnosis: placental haematoma, subamniotic haematoma, placental teratoma, placental cyst, partial mole, mesenchymal dysplasia, fibroid.
• Complications: polyhydramnios, fetal anaemia, hydrops fetalis, cardiomegaly, fetal growth restriction, preterm birth, preeclampsia, fetal death, neonatal thrombocytopenia.

The approach is ultrasound with Doppler and measurement of fetal anaemia.

• Ultrasound: well circumscribed, round, hypoechoic or mixed mass on the fetal surface of the placenta, protruding into the amniotic cavity, with internal blood flow on colour Doppler.
• Measure the diameter in three planes; amniotic fluid index; hydrops signs (ascites, pleural and pericardial effusion, skin oedema, cardiomegaly).
• Middle cerebral artery peak systolic velocity above 1.5 multiples of the median indicates moderate to severe anaemia.
• Fetal echocardiography, umbilical artery Doppler, maternal full blood count; fetal blood sampling for haemoglobin and platelets in specialist units.

The principle is observation for small tumours and fetal medicine treatment for large ones with hydrops, anaemia or polyhydramnios.

• Supportive: refer tumours above 4 cm to a fetal medicine unit; scans every 1 to 2 weeks; daily fetal movement counts; delivery in a unit with neonatal intensive care.
• Pharmacological: betamethasone 12 mg IM twice, 24 hours apart, between 24 and 34 weeks and 6 days if delivery is likely; indomethacin 25 mg oral 6-hourly for up to 48 hours before 32 weeks for symptomatic polyhydramnios, with scan of the ductus arteriosus; digoxin 0.5 mg oral 8-hourly for 3 doses then 0.25 mg oral 12-hourly for fetal heart failure; magnesium sulphate 4 g IV over 20 minutes then 1 g per hour until delivery for 24 hours at most before 32 weeks; neonatal packed red cell transfusion 10 to 20 mL/kg IV for anaemia, and platelets 10 to 15 mL/kg for platelets below 30 x 10^9/L.
• Procedures: amnioreduction of up to 2 litres, no faster than 1 litre per 20 minutes, for symptomatic polyhydramnios; intrauterine blood transfusion with O negative irradiated packed cells to a fetal haematocrit of 40 to 50 percent for anaemia; fetoscopic laser coagulation or alcohol injection of the feeding vessels in specialist units; delivery at 37 to 38 weeks, earlier for hydrops, failure of treatment or abnormal cardiotocography.
• Red flags: hydrops, polyhydramnios, middle cerebral artery peak systolic velocity above 1.5 multiples of the median, reduced fetal movements, rapid enlargement of the mass.
• Follow-up: scan with Doppler every 1 to 2 weeks; growth scans every 2 weeks; newborn haemoglobin, platelets and blood film at birth and on days 2 to 5.