TB was described by Sandifort in 1785 as a right upper bronchus originating in the trachea. In the recent literature, the term TB encompasses a variety of bronchial anomalies originating from the trachea or main bronchus and directed to the upper lobe territory. These may be displaced or supernumerary (accessory) . A classification of aberrant bronchi directed to the upper lung lobes is displayed as line-diagram (Fig. 4). By this classification, our patient had displaced right TB. Other authors have described similar anomaly as tracheal trifurcation. Displaced right TB is incidentally the commonest type of bronchial anomaly reported in literature [8,9].
Figure 4: Schematic representation of aberrant bronchi to the upper lobes: prearterial (true right tracheal) (1), preeparterial (right “tracheal”) (2), posteparterial (3), eparterial (true left tracheal) (4), eparterial (left “tracheal”) (more ...)
The prevalence of TB in normal population is 2% or less. It is 7 times more common on the right side. Almost all the TB reported in association with EA previously have been reported on right side [6,8,10].
Our patient also had a tracheal diverticulum that could either be a blindly-ending supernumerary bronchus or proximal remnant of an aborted distal TEF .
Patients with TB are usually asymptomatic. However, TB have been known to cause persistent or recurrent upper-lobe pneumonia, atelectasis or air trapping, and chronic bronchitis, bronchiectasis, focal emphysema, and cystic lung malformations. When associated with VACTERL anomalies, TB has been known to coexist with other tracheo-bronchial anomalies such as tracheo-bronchial stenosis or tracheo-bronchomalacia, further adding to the respiratory complications. Associated rib anomalies have also been reported [5-7,8,10].
Traditional diagnostic radiological modality of TB, the bronchography, has been replaced by virtual bronchoscopy and MRI. TB could be directly visualized on bronchoscopy. A few centers routinely do pre-operative bronchoscopy for all EA patients, when a TB may be incidentally diagnosed by experienced anesthesiologist or neonatal surgeon [1,2]. Rarely, the diagnosis is made in an incidental surgery as in our case. Had we not performed a thoracotomy, and straightaway headed to perform the cervical and abdominal esophagostomies, the diagnosis could have been missed, may be forever.
Different centers have different policies about anesthesia for EA with TEF patients. While most of the anesthetists plan placing an endotracheal tube just above or below the TEF, few prefer doing left bronchus intubation, or using double-lumen tube. Endotracheal intubation in a patient with a TB can cause obstruction of the TB leading to shunting and hypoxemia. Intubation of the TB may result in hypoxia, atelectasis, or both during anesthesia. Similar complications may be encountered postoperatively when EA patient having undergone primary anastomosis is electively ventilated. Recognition of a TB before induction of intubation can be helpful for determining optimal positioning of the endotracheal tube .
Most patients with TB can be treated conservatively; however, in symptomatic patients surgical excision of the involved segment is necessary. Though rare, lung cancer arising from TB has been reported [11,13].
It is proposed that precise tracheo-bronchial anatomy should be known in all the patients of EA. It is suggested that in those centers where a preoperative bronchoscopy is not performed for patients of EA, a flexible bronchoscopy may be performed in infancy to rule out associated tracheomalacia and TB.