Congenital Pulmonary Airway Malformation: APSA Prenatal Counseling Series

American Pediatric Surgical Association Prenatal Counseling Series Congenital Pulmonary Airway Malformation from the Fetal Diagnosis and Treatment Committee of the American Pediatric Surgical Association Editor-in-Chief: Ahmed I. Marwan, MD ©2018, American Pediatric Surgical Association TM American Pediatric Surgical Association Prenatal Counseling Series Congenital Pulmonary Airway Malformation Differential Diagnosis Differential diagnosis of a prenatally diagnosed cystic lung lesion includes: congenital pulmonary airway malformation (CPAM), bronchopulmonary sequestration (BPS), hybrid lesions, bronchial atresia, congenital diaphragmatic hernia and bronchopulmonary foregut malformations. Courtesy of Mariana Meyers, MD, Colorado Fetal Care Center American Pediatric Surgical Association Prenatal Counseling Series Congenital Pulmonary Airway Malformation How to Measure CVR The CPAM volume is estimated using the formula for prolate ellipse CPAM volume = (length x height x width x 0.52) CPAM volume ratio = CPAM volume/head circumference American Pediatric Surgical Association Prenatal Counseling Series Congenital Pulmonary Airway Malformation Initial Evaluation Obstetrical Ultrasound Fetal echocardiography Fetal magnetic resonance imaging Obstetrical Ultrasound • For anatomy, growth and fluid • Document whether the lesion is microcystic (multiple cysts, solid <5mm) or macrocystic (>5mm) • Search for a systemic feeding vessel: BPS/hybrid lesion • Measure the CPAM Volume Ratio (CVR) • Mediastinal shift • Signs of hydrops: pleural fluid, ascites, pericardial fluid, skin edema, placentamegaly Echo • Cardiac structure and function • Vascular supply of the lesion • Pulmonary veins • Signs of hydrops Fetal MRI • Delineate anatomy • Vascular supply American Pediatric Surgical Association Prenatal Counseling Series Congenital Pulmonary Airway Malformation Prenatal Counseling Low-risk lesions (CVR < 1.6) • Weekly CVR and growth Ultrasounds every four weeks • Expectant management in low-risk cases without a dominant cyst • In the presence of a dominant cyst (> 2cm), consider an MRI at 34 weeks GA to evaluate for hyperinflation/mediastinal shift and need for delivery at a tertiary center with ECMO capability High-risk lesions (CVR > 1.6) Referral to a fetal center • Weekly or twice weekly ultrasounds depending on severity • Betamethasone 12mg IM to be repeated in 24-48 hours • Consider fetal MRI at 34 weeks • Hydrops < 32 weeks GA o Macrocystic lesion: thoracoamniotic shunt o Microcystic lesion: open fetal resection • Hydrops > 32 weeks GA o EXIT-to-fetal CPAM resection • Emergent Cesarean section with ECMO standby and postnatal resection American Pediatric Surgical Association Prenatal Counseling Series Congenital Pulmonary Airway Malformation Prenatal Considerations • Usually diagnosed on a prenatal screening ultrasound • Prenatal natural history characterized by progressive growth until 26-28 weeks GA • May regress in up to 50-60% of cases • CVR at first presentation is prognostic. CVR < 1.6 = good prognosis. • Pulmonary hypoplasia may occur secondary to mass effect • Polyhydramnios may occur secondary to esophageal obstruction • Lesions with a CVR > 1.6 have a 75% risk of hydrops Postnatal Considerations • Perinatal air trapping within the cysts may occur, resulting in respiratory distress • Communication with the airways may result in recurrent infections • Malignant degeneration to pleuro-pulmonary blastoma (PPB) is reported