Pulmonary agenesis is a condition characterized by the underdevelopment, incomplete development, or complete absence of one or both lungs. When only one lung is affected (unilateral agenesis), the condition is not always fatal. When both lungs are affected (bilateral agenesis), the condition is considered uniformly fatal. Bilateral agenesis is exceptionally rare, with only 14 cases reported since 1885. Unilateral agenesis is 25 times more common than bilateral, and it may be considered compatible with life.
Pulmonary agenesis may be an isolated diagnosis, or it may be associated with other malformations. Pulmonary agenesis can be associated with anomalies in the gastrointestinal, genitourinary, ocular, and central nervous systems. It may also be associated with spinal and craniofacial defects. Cardiac malformations like atrial septal defect (ASD) and ventricular septal defect (VSD) can occur with pulmonary agenesis. Polyhydramnios, oligohydramnios, and hydrops fetalis have been reported in cases of pulmonary agenesis. Due to the high incidence of associated anomalies, a detailed ultrasound, MRI, or CT scan should be conducted to scan for additional abnormalities in other systems and structures.
The exact incidence rate of pulmonary agenesis is unknown, but it has been estimated as having a prenatal incidence of 1 in 15,000. Females are slightly more likely to be affected than males. In cases of unilateral pulmonary agenesis, agenesis of the right side is associated with worse outcomes as 50% of right-sided cases have associated anomalies including severe cardiac malformations.
The prognosis for pulmonary agenesis varies based on whether the condition is unilateral or bilateral and whether or not there are any other associated anomalies. An estimated 50% of children with pulmonary agenesis are either stillborn or die within the first few years of life.
Pulmonary agenesis is not associated with chromosomal abnormalities, and the recurrence risk is non-existent.