*4.2.2. Drainage procedures*

surgery and neonatology services are prepared to care for the infant. The fetal lung maturity prior to delivery should not be assessed [43]. Up to 50% of cases require extracorporeal membrane oxygenation (ECMO); therefore, the delivery at a tertiary center with ECMO capability is recommended [43]. Cesarean delivery is performed for standard obstetrical indications [43].

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 dis-

**1.** Congenital pulmonary airway malformation volume ratio (CVR)—Obtained by calculating the volume of the lung mass using the formula for the volume of an oval and normalizing it by gestational age. To normalize by gestational age, the lung mass volume should be divided by the head circumference. CVR = height x anteroposterior diameter x transverse

**2.** Mass-to-thorax ratio (MTR)—The ratio between the transverse diameter of the mass and the transverse diameter of the thorax. It is measured on an axial image of the chest, where

**3.** Observed to expected lung-to-head ratio (o/e LHR)—Initially described as a predictor of

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

• 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

**4.2. Congenital pulmonary airway malformation**

484 Congenital Anomalies - From the Embryo to the Neonate

ease and should include the following [61]:

diameter x 0.52 (constant)/head circumference.

the four-chamber view of the heart is present.

outcome in congenital diaphragmatic hernia.

*4.2.1. Pregnancy management*

rates ≥95% [61].

• Thoracentesis—For fetuses with large pleural effusions, thoracentesis to prevent pulmonary hypoplasia is possible, but rapid reaccumulation of fluid limits its usefulness [61]. The fluid should be sent for cell count to exclude an infectious etiology [61].

• Cyst aspiration should decompress a large macrocyst and reverse the mediastinal shift. Although fluid reaccumulation is common and limits its usefulness [61].

in rare instances or, more often, cannulation for extracorporeal membrane circulation, thus creating a controlled situation for delayed removal of the CPAM. Overall fetal survival of 90%

Management of Pregnancy and Delivery in Prenatally Diagnosed Congenital Anomalies

http://dx.doi.org/10.5772/intechopen.71802

487

Bronchopulmonary sequestration (BPS) is usually a small lesion and decreases in size in late

• Assessment of additional anomalies and genetic evaluation. When a lung mass is first identified, thorough assessment for additional anomalies is necessary. Intralobar sequestration is not associated with an increased risk of additional anomalies [68]. Extralobar BPS is associated with anomalies in up to two-thirds of cases [68]. These anomalies include chest wall and vertebral anomalies hindgut duplications, diaphragmatic hernia, congenital heart disease, and renal and intracranial abnormalities [68]. The incidence of chromosomal abnormalities is not increased above baseline in fetuses with BPS alone [68]. Karyotype analy-

Parents should be counseled about the possible course of the BPS during pregnancy. At initial presentation in the early midtrimester, it is difficult to accurately predict what the outcome will be for an individual fetus, but some predictions are possible, e.g., a large BPS with

• Follow-up assessment. All patients should have serial prenatal follow-up examinations to assess change in size of the lung mass and development of hydrops [68]. The frequency depends on the size of the lesion. The larger lesions should be followed more closely. The presence of hydrops is a sign of impending fetal demise and an indication for fetal intervention [68]. This recommendation is based on results from small case series showing higher survival rates if hydrops resolves [68]. Because hydrops is uncommon, fetal intervention is rarely required and is warranted only in cases where the fetus is severely compromised and remote from term. For fetuses greater than 32–34 weeks of age, early delivery with im-

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 [69]. These interventions should only be undertaken at centers experienced in fetal surgery. Prenatal intervention requires extensive counseling to the parents on the potential

• Fetal intervention. If the BPS is solid with a large pleural effusion, thoracentesis to prevent pulmonary hypoplasia is possible, but rapid reaccumulation of fluid limits its usefulness. It can be used as a temporizing maneuver to provide prognostic information about the possible result from placement of a thoracoamniotic shunt [68]. The fluid should be sent for cell

has been reported [61].

*4.3.1. Pregnancy management*

**4.3. Bronchopulmonary sequestration**

gestation in about 75% of cases [68].

sis is recommended prior to initiating fetal therapy.

hydrops in the second trimester is likely to do poorly [68].

mediate postnatal resection is a reasonable option [68].

risks versus benefits of surgery.

• Thoracoamniotic shunt provides a therapeutic option for select fetuses with large macrocystic lung lesions or pleural effusion at risk for hydrops and/or pulmonary hypoplasia. Survival following shunting depends on gestational age at birth, reduction in mass size, and hydrops resolution [66]. Complications include displacement or malfunction of the catheter, thrombus occlusion of the catheter, fatal fetal hemorrhage, procedure-related abruptio placentae, premature rupture of membranes, and preterm labor [61].
