1.What should I do if I find fetal cystic adenoma?
Congenital cystic adenomatous malformation (CCAM) is an overgrowth of the fetal terminal bronchus that forms a clearly defined lesion in the lung parenchyma, often involving part of the lung lobes or the entire lung lobes, and may involve the lung parenchyma unilaterally or bilaterally, and 90% of the lung parenchyma may be mediastinally displaced. It may involve part of the lung parenchyma or the entire lung parenchyma. In general, fetal cystadenoma is a treatable benign lesion with a good prognosis in most cases. Termination of pregnancy upon detection is not recommended.
2. What is the cause of CCAM?
The exact etiology of CCAM is not fully understood.
3.What is the prenatal diagnosis of CCAM by ultrasound?
The prenatal diagnosis of CCAM by ultrasound is divided into three types.
Type I is a large cystic type, in which a cystic mass is seen in the chest cavity with a cystic cavity diameter >2?cm, without separation, and lung tissue echogenicity is seen around the cystic mass.
Type II is a microcystic type, in which cystic masses are seen in the chest cavity, manifesting as multiple small cysts with cavity diameter <50px.
Type III is a mixed type, also known as multicystic lung, which is formed by the fusion of smaller cysts with lung tissue, and is characterized by enlarged lobes in the affected thoracic cavity with enhanced and uniform echogenicity and mediastinal shift to the opposite side.
4.What is the prognosis of CCAM?
The prognosis is good for CCAM type I and type II, but type III is prone to fetal edema and poor prognosis.
CCAM is most commonly found between 18 and 26 weeks and the size of the mass, the rate of change in mass size and whether it causes fetal edema are important indicators of fetal prognosis. One of the most common methods is to calculate the cephalopulmonary ratio (CVR) by ultrasonography, which is the volume of the pulmonary mass (volume is W*H*L*0.523)/fetal head circumference, and when the CVR is ≤1.6, 86% do not have edema; for >1.6, 75% have edema. In cases without edema, the mass tended to decrease gradually after about 25-28 weeks. In contrast, the mortality rate is high in those who develop edema. Conservative treatment is still the appropriate choice when the fetus does not show edema or excessive amniotic fluid.
5.What are the prenatal diagnosis methods of CCAM?
Prenatal ultrasound is the preferred screening method for CCAM. After the first detection of CCAM by ultrasound during pregnancy, close labor and delivery examination should be performed, and the number of ultrasound examinations should be increased. The growth of the lesion and the presence of mediastinal shift, fetal edema, fluid in the chest or abdomen, and excessive amniotic fluid should be followed up regularly to determine the prognosis and the timing of pregnancy termination. If necessary, MRI can be used to detect more details of congenital structural malformations, which can help in the comprehensive assessment of the fetus before delivery and the development of treatment plan after delivery.
6. Can a fetus with CCAM be expected to deliver naturally at full term?
If fetal CCAM is detected prenatally, delivery is usually chosen after 32 weeks. If there is no symptom, natural delivery can be chosen; if there is mediastinal shift, microcystic type, or suspected airway obstruction, cesarean delivery is recommended. Emergency cesarean section should be performed after 32 weeks of gestation in case of excessive fetal edema or occupying lesions and difficulty in vaginal delivery, and emergency surgical treatment after birth.
7.What are the treatment methods of CCAM?
①Hormone therapy
Indications for hormonal treatment of CCAM: CCAM cases of high-risk microcystic type; presence of fetal edema; CVR>1.6. Hormonal treatment is an effective method in high-risk microcystic CCAM cases.
(ii) Shunt puncture
The drainage of cysts (shunt puncture) requires, first of all, a visualization system to keep track of the mass as well as the specifics of the puncture. The fetoscope is applied to place the drainage tube between the thoracic cyst and the amniotic cavity under the guidance of the visualization system for treatment purposes. Evaluation of the shunt: The visualization system is used to understand the postoperative reopening of the lung and the possible detection of previously undiagnosed cases of pulmonary isolation and to stop the continued progression of edema. The drainage fluid can be subjected to relevant laboratory tests: cytology for the presence of lymphatic fluid exudation; indicators of infection; karyotype of the fetus. Indications for treatment include the presence of edema in the fetus and the presence of signs of pulmonary dysplasia.
(iii) EXIT procedure (extra-uterine fetal surgery during delivery? ex-utero? intrapartum? therapy?, EXIT)
EXIT surgery is performed at the time of birth, when the fetus is delivered by cesarean section but the umbilical cord is not broken, and the CCAM tumor is removed first, and then the umbilical cord is broken to allow the newborn to start breathing in order to relieve the pressure of the mass on the chest and relieve respiratory distress.
Principles of EXIT surgery: presence of severe mediastinal shift; ? The EXIT procedure requires careful planning and complete teamwork, including anesthesia, cardiac circulation, neonatology, nursing, obstetrics, pediatric surgery, and extracorporeal membrane lung (ECMO) support. The risks that may arise after birth include: recurrence, airway fistula, hemorrhage, celiac disease, sepsis, gastroesophageal reflux, etc. Essential to the success of the EXIT procedure is ensuring gas exchange in the uteroplacenta and hemodynamic stability of the fetus. In addition, the family must be informed of the potential risks, including maternal hemorrhage, the need for further lung tissue removal after birth, prolonged NICU monitoring, and the corresponding increased costs. Risks to the mother include excessive amniotic fluid, preterm delivery, chorioamnionitis, and hemorrhage.The EXIT procedure allows for rapid removal of the pulmonary mass after birth, eliminating acute respiratory failure due to mediastinal shift, air trapping, and compression of normal lung tissue.
④ Open fetal surgery
The principles or goals of fetal surgery are: to restore normal anatomy; to restore normal physiology; and to allow the lungs to grow and develop before birth. There are no clear indications for performing open fetal surgery in the fetal period. For asymptomatic or non-edematous CCAM with a CVR <1.6, the changes can be observed dynamically. In contrast, a large mass with CVR >1.6 and significant compression or obvious mediastinal shift, a tendency to edema or pre-existing edema, and excessive amniotic fluid mostly require intervention in the fetal period, including open fetal surgery.
⑤ Surgical options after birth
The majority of cases can be treated surgically after birth because of the low number of other congenital malformations associated with CCAM, and early surgical resection has become a generally accepted view. However, there is also a view that no further treatment is needed after birth (18% of all prenatal diagnoses). Those with a prenatal fetal diagnosis of CCAM all require a repeat CT examination after birth to clarify the diagnosis. Those with definite symptoms after birth require emergency surgical treatment; there are no clear criteria for when to operate in asymptomatic cases. Surgery should be chosen at least 1 month after birth, because the risk of anesthesia begins to decrease gradually at 4 weeks of age. Factors associated with the need for surgical resection are the presence of significant respiratory symptoms, recurrent infections and risk of mass malignancy; other clinical manifestations such as coughing up blood, hemothorax, etc. However, there is an opinion that it is best not to wait until symptoms are present before surgery, as that has an impact on overall lung development.