OLV is often performed for thoracic surgery, especially video assisted thoracoscopic surgery (VATS), which is a widely used surgical modality. Although DLT is the most common device for lung isolation, bronchial blockade technology is increasing. The use of BB is advantageous over the DLT in difficult intubation situations, in small adults or children, and eliminates the need for a tube exchange when postoperative mechanical ventilation is essential [
2]. However, in cases with an undiagnosed TB, there are several reported cases that are unable to isolate the right lung with BB [
3,
4]. Using a left-sided DLT made it possible to perform complete OLV in our cases after failing to collapse the right lung, using BB. Typically, patients with TB can be well managed with a left DLT [
3,
4]. If a left DLT is not adequate, other potential solutions, including the use a Fogarty catheter to block the TB in addition to a Univent tube [
5], only a Univent tube or one BB blocking of a TB [
6-
8] or the use a Fogarty catheter in the TB with BB located in the right main bronchus [
8]. The normal RUL bronchus arises from 1-3 cm, distal to the carina; otherwise, TB is usually 2 cm above the carina [
1]. TB may be displaced or supernumerary (
Fig. 2). A displaced TB is defined when the normal RUL bronchus or segment is transposed from the right main bronchus to the trachea. There is no actual RUL bronchus coming from the right main bronchus. Supernumerary TB is the accessory segments or bronchi when there is a normal trifurcation of the RUL bronchus [
9]. This congenital anomaly is frequently regarded as an incidental finding during bronchoscopy or radiologic examination, but it is occasionally contributing to the respiratory disease, such as pneumonia [
1,
9]. According to previous reports, although, most of the tracheobronchial tree anomalies are well diagnosed on a conventional chest CT [
10], there are inherent limitations of conventional CT for displaying airways anatomy [
11]. Multidetector CT scanner and computerized reconstruction methods can help to overcome these limitations, but higher quality 2D and 3D reformation images are not conventionally done [
11]. A coronal CT scan identified a TB only in the third case; thus, fiberoptic bronchoscopy played a crucial role in the detection of TB [
12]. We reported that the incidence of TB is 0.45% at bronchoscopy. This figure agrees with the previously reported incidence, which ranges between 0.1 and 5% [
1]. Even though the incidence of TB is low, careful bronchoscopic examination is highly recommended before right the insertion of BB to detect any tracheobroncheal anomaly when left-sided OLV using BB is planned. Further, when a TB is found, DLT insertion is recommended than that of blocker insertion to achieve OLV completely.