*4.2.1. Pregnancy management*

Prenatal diagnosis of congenital pulmonary airway malformation (CPAM) has increased with widespread use of prenatal ultrasonography and magnetic resonance (MR) imaging. When CPAM is diagnosed, the quantitative evaluation helps predict the prenatal course of the disease and should include the following [61]:


The prenatal course depends on the gestational age, size of the mass, amount of mediastinal shift, fetal hemodynamics, and associated anomalies, more than the type of lesion [61]. About 50% of masses persist to delivery [62]. Fifteen percent of these masses decrease in size during the late second and the third trimesters; the majority have a relative decrease in size due to normal fetal thoracic growth, but a few increase in size [61]. It is difficult to predict at the time of the initial ultrasound whether lesions will regress, stabilize, or continue to grow and lead to significant problems, including hydrops, need for surgical intervention or postnatal respiratory assistance, or death. The use of CVR, MTR, and, to a lesser degree, o/e LHR helps better identify patients at risk [61, 63]. A CVR >1.6 is predictive of risk for hydrops, respiratory distress at birth, and probable need for early surgery [61], whereas a CVR <0.91 at presentation predicts a favorable outcome so follow-up examinations can be less frequent [61, 63]. A MTR <0.51 suggests the fetus is at low risk for developing complications [61, 63]. In the absence of hydrops, the prognosis is good with reported live birth rates ≥95% [61].

• Assessment for associated anomalies. A comprehensive fetal survey, including fetal echocardiography, should be performed as 10–20% of fetuses with CPAM have associated congenital abnormalities, such as esophageal atresia with tracheoesophageal fistula, bilateral renal agenesis or dysgenesis, intestinal atresia, other pulmonary malformations, and diaphragmatic, cardiac, central nervous system, and bony anomalies [61]. Fetal echocardiography is recommended in all patients at time of diagnosis to rule out congenital cardiac anomalies.

• Follow-up assessment. All patients should have serial prenatal follow-up examinations every 1 to 4 weeks to assess change in size of the lung mass, change in CVR, and development of polyhydramnios and hydrops [61]. The frequency depends on the gestational age and CVR. Closer follow-up should be performed in those patients at high risk of developing hydrops (CVR ≥1.6, age < 26 weeks), whereas the interval between examinations can be lengthened if the CPAM is very small, CVR is <0.91 [63]. The presence of hydrops is a sign for impending fetal demise and thus it is an indication for fetal intervention [61]. The recommendation of proceeding with fetal intervention is based on results from small case series showing good survival (>90%) if hydrops resolves [61].

For fetuses greater than 32–34 weeks of age, early delivery with immediate postnatal resection is a reasonable option [61]. Ex utero intrapartum therapy (EXIT) has been used to stabilize fetuses with large lesions expected to have difficulty breathing at delivery [64].

For gestations between 20 and 32 weeks, several interventions with the goal of improving fetal hemodynamics and preventing lung hypoplasia have been described and appear to improve survival [61]. Drainage procedures are used for CPAMS with dominant cysts, while solid masses are treated by resection or ablation. Karyotype analysis is recommended prior to initiating fetal therapy [61]. All of the following interventions should be considered investigational.

Antenatal corticosteroids are the only medical treatment of CPAM. They are used primarily for treatment of microcystic CPAM, since these masses cannot be managed by minimally invasive procedures, but have been used for macrocystic disease, as well [61]. In uncontrolled studies, maternal steroid administration appeared to reverse hydrops and improve outcome [61]. Multiple courses of antenatal betamethasone for high-risk fetal CPAMs often result in favorable short-term outcomes without the need for open fetal resection. The fetuses who did not respond to a first course of steroids stabilized or improved (e.g., reduction in lesion size, resolving hydrops) after receiving two to four courses of therapy [65]. The median interval between the first and second courses of steroids was about 2 weeks (range 1–6 weeks) [61].

• Fetal intervention. Successful fetal surgery depends on surgical experience, optimal maternal anesthesia, uterine relaxation, hysterotomy, fetal exposure, and intraoperative fetal monitoring.
