At present, there is no specific surgical management that allows survival in cases of tracheal agenesis. Normally, a newborn with tracheal agenesis presents with immediate respiratory distress and an absent or very weak cry. This rare congenital anomaly might confound the attending doctor in the delivery room or operating theatre.
The embryopathology resulting in this abnormality occurs during the first eight weeks of gestation. The tracheo-pulmonary complex develops from the respiratory diverticulum at the ventral aspect of the primitive foregut. A compromised vascular supply to the developing trachea during this stage may cause tracheal agenesis or tracheal stenosis with complete tracheal ring . According to Merei et al , the point of bifurcation between the developing trachea at ventral and developing esophagus at dorsal foregut remains fixed in relation to the cervical vertebra. Caudally, the respiratory diverticulum will develop into the carina and broncho-pulmonary tree. The cephalic aspect of the respiratory diverticulum will be elongated to form the trachea and the infra-glottic structure. Tracheal agenesis results when this normal elongation process fails to take place . This anomaly is associated with relatively normal supra-glottic structures and pulmonary development, as seen in this case. The congenital abnormality is only limited to the region of the developing trachea. The severity of tracheal agenesis was described in detail by Floyd and colleagues and classified into three types . In Type I, a short segment of the trachea fails to elongate to fuse with the larynx. In Type II, the respiratory diverticulum fuses in midline to form the carina but tracheal elongation does not take place. And in type III, the respiratory diverticula does not fuse in the midline, resulting in two fistula opening at the lower part of esophagus. The present case is compatible with a type III abnormality. Type II remains the most common abnormality (61%), followed by type III (23%) and type I (11%) .
Tracheal agenesis is commonly associated with other congenital anomalies such as vertebral defects, anal atresia, tracheoesophageal fistula, esophageal atresia, cardiovascular defects, limb defects, duodenal atresia and renal defects. Tracheal agenesis can be a manifestation of several syndromes such as VATER (vertebrae, anus, trachea, esophagus, and renal), also known as VACTERL, and TARCD (total alkaloids from rhizoma corydalis decumbeutis).
A high index of suspicion is required to diagnose tracheal atresia. Antepartum features that would corroborate such suspicion are the presence of polyhydramnios with multiple fetal anomalies. During birth, the baby may not cry or may have a weak cry. An acute severe respiratory distress develops and multiple attempts at intubations fail. Laryngoscopy will reveal immobile vocal cords lying in the midline position. Other findings are a cleft between the arytenoids, as well as associated congenital anomalies. Good oxygenation may be maintained with bag-mask ventilation or esophageal intubation. The diagnosis is made through neck exploration during emergency tracheostomy and an endoscopic evaluation of the larynx and esophagus. A pre-delivery procedure with three-dimensional ultrasound or fetal magnetic resonance imaging allows a complete evaluation of this upper airway abnormality. The ex-utero intrapartum treatment (EXIT) procedure can be planned based on the imaging results. EXIT procedure can reduce the risk of respiratory distress immediately after birth .