Prenatal treatment of chorioangioma by microcoil embolisation

Authors


* Dr T. K. Lau, Department of Obstetrics and Gynaecology, The Prince of Wales Hospital, Shatin, Hong Kong.

Case report

A 39 year old parous woman had a huge chorioangioma complicated by fetal anaemia. Her past obstetric history was unremarkable, with three normal vaginal deliveries at term. In her current pregnancy when she was first seen at 24 weeks of gestation, her fundal height was 28 cm. An ultrasound scan showed a placental tumour measuring 10 cm in diameter protruding into the amniotic cavity. The placenta was anterior. The tumour was predominantly solid with multiple echo-free spaces. Colour Doppler examination revealed a vascular tumour, with a large feeding vessel measured 7.4 mm in diameter supplying the tumour. The feeding vessel bifurcated soon after its entry into the tumour (Fig. 1). Fetal measurements were on the third centile, and there was cardiomegaly with a cardiothoracic ratio of 0.62 (Fig. 2). The fetal morphology was otherwise normal. The liquor volume was also diminished, with only one identifiable pocket of 3.7 cm in diameter.

Figure 1.

Ultrasonogram showing the feeding vessel of the chorioangioma bifurcating after its entry into the tumour.

Figure 2.

Ultrasonogram showing cardiomegaly and pericardial effusion (arrow).

A diagnosis of chorioangioma with possible fetal anaemia was made. Cordocentesis was performed and confirmed fetal anaemia (haemoglobin concentration: 5.7 g/dL). Intrauterine transfusion was performed with 50 ml of irradiated Rhesus-positive maternal packed cells (haematocrit of 80%), and the haemoglobin level increased to 9.6 g/dL. The fetal karyotype was normal.

To prevent the recurrence of fetal anaemia due to chronic sequestration of fetal blood through the tumour, other treatment was considered to be necessary. Ultrasound-guided transcutaneous embolisation of the chorioangioma was performed two days later under local anaesthesia. Eight pieces of microcoil, including two 2-mm/3-mm coils, two 2-mm/5-mm coils and one 2-mm/6-mm coil, were inserted into the main and intratumoural branches and at the bifurcation of the main trunk of the feeding artery through a 15-cm-long, 20-gauge spinal needle. A significant reduction of blood flow was observed (Fig. 3) but the procedure was abandoned because of increasing discomfort felt by the woman due to prolonged sustained supine posture. The procedure lasted 45 minutes.

Figure 3.

Ultrasonogram showing cessation of blood flow distal to a microcoil (arrow).

Intrauterine transfusion and embolisation were repeated under general anaesthesia one week later because of persistent cardiomegaly and fetal anaemia. The fetal haemoglobin increased to 12.8 g/dL after transfusion of 60 ml of irradiated maternal packed cells. The blood flow to the tumour was diminished after nine pieces of microcoil were inserted.

Although the blood flow into the tumour was significant reduced, cardiomegaly and fetal anaemia persisted. Further attempts at embolisation were therefore considered not to be justified. The fetal haemoglobin level decreased approximately 6 gm/dL every week, and repeated intrauterine transfusions were required at 27, 28 and 29 weeks of gestation. The size of the chorioangioma slowly increased to 18 cm in diameter over this time.

The woman went into spontaneous labour at 29 weeks and 6 days. An emergency classical caesarean section was performed for fetal malpresentation. The baby weighed 1.185 kg, with an umbilical arterial pH of 7.161. The baby died on the second day of life because of prematurity, heart failure and disseminated intravascular coagulopathy.

The placenta with the tumour weighed 2.75 kg. The tumoural mass measured 20 × 18 × 17 cm. There was extensive infarction involving over 60% of the tumour volume. Microcoils and thrombus formation were identified within the feeding artery and its branches (Fig. 4). Microscopic examination showed that the chorioangioma was composed of predominantly capillary-sized vascular channels in the fibromyxoid matrix and confirmed the presence of thrombosis of the feeding arteries and infarctions.

Figure 4.

Placenta with microcoils and thrombus formation within the feeding artery and its branches. At the centre is a microcoil (arrow) that was distorted during sectioning of the specimen.

Discussion

Small placental chorioangiomas are found in 1% of pregnancies and are often of no clinical significance1. Large chorioangiomas (diameter larger than 5 cm) are much less common, with an estimated incidence of 1 in 2000–3500 births, but are associated with high perinatal mortality of 40%2. The fetuses are at risk of severe fetal anaemia due to sequestration of fetal blood in the tumour and the presence of a large arteriovenous shunt within the tumour may also leads to high-output heart failure, hypoxia and fetal distress3,4. In general, small chorioangiomas or those not associated with fetal cardiac failure required no treatment. In the presence of fetal cardiac failure, hydrops or fetal anaemia, intrauterine therapy should be considered if the gestational age precludes early delivery. Several prenatal interventions with variable fetal outcome have been reported, including intravascular transfusion5–8, fetoscopic devascularisation9 and devascularisation with intravascular injection of absolute alcohol10. We reported a case of a huge chorioangioma treated prenatally with embolisation using microcoils.

Although intravascular transfusion is the most common treatment, it at best gives only temporary relief from anaemia and does not deal with the primary pathology. As fetal red blood cells are continuously being lost or destroyed within the tumour, repeated transfusions are expected, particularly when anaemia has already occurred in early pregnancy, as in our case. Risks of repeated transfusions, including preterm labour and iron overload, are substantial8. Therefore, some form of embolisation or devascularisation of the tumour is necessary. However, there is no consensus on which method is the best.

Quintero et al.9 have reported the treatment of a chorioangioma measuring 8.5 cm in diameter by fetoscopic ligation and bipolar electrosurgery. Unfortunately, the fetus died on the third post-operative day. In our case, major technical difficulties of fetoscopic surgery were anticipated, including an anterior placenta and the limited space for manipulation due to the huge size of tumour and oligohydramnios.

Nicolini et al.10 reported the treatment of two chorioangiomas with a maximum dimension less than 6 cm by injection of absolute alcohol into the tumoural veins, and both babies survived. The injection of absolute alcohol induces an immediate intravascular coagulation and thereby devascularises the tumour. Alcohol injection under ultrasound guidance is a technically simple procedure. However, there is at least a theoretical risk that alcohol may reach the fetal systemic circulation leading to fetal organ damage, especially when treating a large tumour when a large volume is required. Similar concerns also apply to the injection of thrombogenic material or sclerosing agents into the feeding arteries because of the potential presence of arteriovenous shunts within the tumour.

In our case, we decided to insert microcoils into the feeding arteries of the chorioangioma to induce thrombosis and devascularisation of the tumour. Microcoils are made of stainless steel wire arranged in a helical fashion forming a conical configuration. The coil contains polyester fibres protruding out perpendicularly from the wire of the coil. The coil slightly stretches the vessel and lodges within the lumen, causing mechanical blockage of the vessel, while the fibres trap the circulating platelets, resulting in thrombus formation. This method has been reported to be effective in inducing vascular thrombosis and interruption of blood flow and has been successful in treating a variety of conditions in adults in which vascular thrombosis is required11–13. The experience of using microcoils in obstetric patients, however, is limited14.

The advantages of microcoil embolisation are that it is technically simple under ultrasound guidance and that there is no risk of distal embolisation of the fetal circulation. The two attempts in our case did not result in any maternal or fetal complications. An immediate significant reduction in blood flow was observed, confirming its therapeutic value. Theoretically, for tumour embolisation, it is always better to have distal embolisation as near the tumour as possible to minimise collateral formation. Therefore, in this case, we have embolised both the main branches as well as the intratumoural branches of the feeding arteries, rather than the main feeding artery itself. However, due to the size of these microcoils, we could only occlude the larger intratumoural feeders but not the microcirculation that might subsequently be supplied by collaterals after occlusion of the feeders. This might account for the failure of total occlusion of vascular supply in our case. Therefore, after two attempts, further treatment was considered unjustified in this case. The woman went into preterm labour, which was probably related to the subsequent multiple intrauterine transfusion procedures. Pathological examination of the placenta confirmed the extensive necrosis caused by the thrombosis induced by the microcoils. The blood supply to the chorioangioma, however, could not be completely obliterated because of the multiple vascular connections and the huge size of the tumour.

Our case report suggests that microcoil embolisation for the treatment of chorioangioma of the placenta is technically feasible. It carries no risk of introducing harmful substances into the fetal circulation and is effective in inducing thrombosis and necrosis. Its failure in this case was probably due to the unusually large size of the tumour. However, this method could be one of the options of treating smaller chorioangiomas.

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