Tracheal agenesis

Tracheal agenesis (also known as tracheal atresia) is a rare birth defect with a prevalence of less than 1 in 50,000 in which the trachea fails to develop, resulting in an impaired communication between the larynx and the alveoli of the lungs. Although the defect is normally fatal, occasional cases have been reported of long-term survival following surgical intervention. Tracheal agenesis (also known as tracheal atresia) is a rare birth defect with a prevalence of less than 1 in 50,000 in which the trachea fails to develop, resulting in an impaired communication between the larynx and the alveoli of the lungs. Although the defect is normally fatal, occasional cases have been reported of long-term survival following surgical intervention. The disease was first described in 1900 by Payne. To this date, it is estimated that about 200 cases have been reported and published worldwide. Several types of the disease have been described and the slight anatomical variations have resulted in the establishment of different classification systems. There are three main types of tracheal agenesis, designated Types I, II and III. In 2013, a case was reported of a South Korean child with tracheal agenesis who had been successfully treated after having been kept alive in an intensive care unit for the first two and a half years of her life. She then had an artificially created trachea implanted that had been created by tissue engineering using her own stem cells. The patient however later died from complications. The disease has been more frequently observed in males than in females, at a ratio of 2:1. Observable signs and symptoms of the disease differ depending on whether the observation in done in utero or after parturition. Only the signs and symptoms of the embryo are described, due to the lack of research in maternal symptoms. The classic in-utero symptoms of tracheal agenesis are an absence of the trachea leading to congenital high airway obstruction syndrome, lung distention, polyhydramnios, heart malformations, heart displacement and hydrops fetalis. Other congenital malformations such as genitourinary, gastrointestinal and musculoskeletal anomalies are common and occur in 80% of the reported cases. Tracheal agenesis may lead to a distention of the foetus’ lung due to a build-up of pulmonary fluid within them. In this case, ultrasound scans show bilaterally enlarged and homogeneously echogenic lungs as well as the inversion of both hemidiaphragms . Although lung distention has been described as a classic symptom, hypoplasia or complete aplasia of the lungs can also occur, in an estimated 26% of cases. In some cases, normal lung development was also reported in neonates with tracheal agenesis. The abnormal development of the foetus’ lungs leads to cardiovascular abnormalities. Distention of the lungs results in a compressed and displaced heart, hindering the normal growth and development of the organ. Depending on the severity of the compression of the heart, normal venous return to the organ would correspondingly be hindered, resulting in a condition known as hydrops fetalis (also known as fetalis ascites) , in which oedema form in the developing foetus. Hydrops fetalis can be observed in utero via ultrasound scan. Polyhydramnios occurs in embryos presenting with a tracheoesophageal fistula as the liquid produced by the lungs supposedly pass to the stomach, in the amniotic fluid.