2 The procedure
2.1.1 Congenital cystic adenomatoid malformations (CCAM) are usually benign tumours, although sacrococcygeal teratomas may be malignant. These tumours can become very large and highly vascular, causing stress on the heart of the fetus. They can lead to the development of non-immune hydrops fetalis (in utero heart failure) and may be complicated by polyhydramnios (excessive accumulation of amniotic fluid). Non-immune hydrops fetalis, placentomegaly, cardiomegaly, large tumour size and high tumour growth rate are associated with poor prognosis, and fetal mortality is high. Obstetric complications include preterm labour and dystocia.
2.1.2 The current options in managing pregnancies with these fetal tumours are: termination of the pregnancy; continuation of the pregnancy without intervention; interventional treatments such as alcohol sclerosis or cyst drainage; and early elective caesarean delivery if significant problems develop. In the latter case, the prognosis is poor even when the fetus is approaching term.
2.2.1 Percutaneous laser therapy for fetal tumours is performed under maternal local anaesthesia and light sedation. A needle is inserted through the mother's abdomen into the uterine cavity under ultrasonographic guidance. An analgesic is then injected subcutaneously or intramuscularly into the fetus, before advancing the needle to the site of the tumour. Colour Doppler imaging is used to guide placement of the needle. A laser fibre is passed through the needle lumen and laser energy is delivered in pulses, causing the blood vessels within the tumour to coagulate. If necessary, laser therapy can be repeated in a further session, usually 1 or more weeks later. Cystic components of tumours may be aspirated during the procedure.
2.3.1 The efficacy and safety of the procedure are based on reports on seven fetuses: two with CCAM and five with sacrococcygeal teratoma.
2.3.2 In a case series of 29 fetuses with sacrococcygeal teratomas, four were treated by percutaneous laser therapy; there were two intrauterine fetal deaths, one neonatal death and one live birth.
2.3.3 In a case series of 67 fetuses diagnosed with cystic lung abnormalities, one fetus with CCAM received two percutaneous laser treatments. Reductions in non-immune hydrops fetalis, mediastinal shift, ascites and blood flow within the tumour were reported following the first treatment. The neonate was delivered at 38 weeks' gestation; surgical excision of the tumour was performed after birth.
2.3.4 In one case report, a fetus with CCAM received two percutaneous laser treatments, both of which had to be terminated early because of fetal bradycardia. Reduction in tumour size was reported following the first treatment. No outcomes were reported following the second treatment.
2.3.5 In another case report, a fetus with sacrococcygeal teratoma received two percutaneous laser treatments. The neonate was delivered by elective caesarean section at 37 weeks' gestation and the tumour was surgically excised after birth. The baby was reported to be healthy and developing normally at 8 months of age. For more details, refer to the 'Sources of evidence' section.
2.3.6 The Specialist Advisers stated that there is uncertainty about the effectiveness of the procedure. Key efficacy outcomes include a decrease in the vascularity of the fetal tumour, leading to potential shrinkage of the tumour in utero, and reduction in cardiac failure in the fetus.
2.4.1 In the case series of 67 fetuses with cystic lung abnormalities, the fetus who received two percutaneous laser treatments died 4 days after birth from sepsis-related complications.
2.4.2 In the case report of a fetus with CCAM, worsening of non-immune hydrops fetalis was reported 4 days after the first treatment. Three days after the second treatment (at a scheduled visit), the fetus was found to have died.
2.4.3 In another case report of a fetus with sacrococcygeal teratoma, bleeding (possibly within the cystic area) occurred following the first treatment, requiring intrauterine blood transfusion. Drainage of blood from the cystic area and drainage of amniotic fluid were performed during the second treatment. For more details, refer to the 'Sources of evidence' section.
2.4.4 The Specialist Advisers stated that theoretical risks include haemorrhage and procedure-related fetal death. There are also uncertainties about the potentially harmful effects of the procedure on other anatomical areas. The theoretical risks to the mother include preterm labour following the procedure, and laser burn if the needle is not sited correctly.