The original SeTB requires two injections with separate skin puncture points [5]. The first injection is performed at the interscalene groove and the second at the supraclavicular fossa to block the superior/middle trunks and the inferior trunk, respectively. We suggest a technical modification to the original SeTB. We often get a corner pocket image of the brachial plexus when performing the supraclavicular approach, as we keep the lateral part of the linear probe (HFL50xp: 15–6 MHz, X-Porte, FUJIFILM SonoSite, Inc., USA) away from the clavicle (Fig. 1A). This imaging technique has several advantages including improved cross-sectional visualization of the plexus and avoiding interference of the trapezius muscle during needle manipulation. Furthermore, it provides a clear image of the suprascapular nerve before it branches out from the superior trunk. A corner pocket injection, the second injection of the original SeTB, can be done using this image. In our institution, 10 ml of local anesthetics (1 : 1 mixture of 0.75% ropivacaine and 1% lidocaine) is usually used at the corner pocket injection. Then, without withdrawing the needle completely out of the skin, the medial part of the probe is rotated in the cephalic direction. Using this rotatory movement, the image for the first injection of the original SeTB can be acquired. Subsequently, the needle can be realigned with the probe (Fig. 1B). At this interscalene level, an additional 10 ml to 15 ml of local anesthetics is administered. Thus, the two-stage blockade can be performed with single skin penetration.

Since the blockade is often performed while a patient is awake, a single skin penetration can significantly reduce the patient’s discomfort. The SeTB presented by the original authors is a more advanced BPB technique. Indeed, it is one of the monumental achievements in ultrasound-guided BPB.