“…A scout scan allows one to identify the midline 34 and accurately determine the interspace for needle insertion, 3,30 which are useful in patients in whom anatomical landmarks are difficult to palpate, such as in those with obesity, 1,23 edema in the back, or abnormal anatomy (scoliosis, 23,48 postlaminectomy surgery, 45 or spinal instrumentation). 42,43,46 It also allows the operator to preview the neuraxial anatomy, 24,26,29,30,33 identify asymptomatic spinal abnormalities such as in spina bifida, 49 accurately predict the depth to the epidural space 19,20,24,26 including in the obese, 50 identify ligamentum defects, 51 and determine the optimal site and trajectory for needle insertion. 26,27 Cumulative evidence suggests that when an US examination is performed before the epidural puncture it improves the success rate of epidural access on the first attempt, 24 reduces the number of puncture attempts 23,24,26,29 or the need to puncture multiple levels, 24,26,29 and also improves patient comfort during the procedure.…”