The block should be performed bilaterally if the surgical procedure is laparoscopic, involves both sides of the abdomen, or includes a midline incision. The block should be performed unilaterally if the surgical procedure only involves one side of the abdomen. The patient should be placed in a lateral position. The transducer is placed in a transverse position between the costal margin and the iliac crest along the mid-axillary line. Initially, the 3 muscle layers of the lateral abdominal wall are identified. The transducer is then slid posteriorly to identify the muscles of the posterior abdominal wall: quadratus lumborum, psoas major, and erector spinae. Insert the needle 2 to 3 cm posterior to the transducer and advance in-plane using a posterior to anterior direction until the needle tip lies within the anterior thoracolumbar fascia between the psoas major and quadratus lumborum muscles.  Inject 3-5 incremental doses of a local anesthetic to a total of 30-40ml per side. For a more thorough review of this block and the QL2 block, use the Block Buddy Pro app.