Comparison of paramedian and transverse ultrasound techniques in assessing the skin epidural distance

Background: Epidural anesthesia relies on accurate epidural space localization, but palpation-based methods can be unreliable due to anatomical variations or spinal changes. Pre-procedural ultrasound, via paramedian or transverse approaches, improves accuracy, though the superior technique remains unclear. Objectives: To measure the skin-to-epidural distance (SED) with ultrasonography (USG) using the paramedian sagittal oblique (PSO) approach and the transverse median (TM) approach, and to assess the complications related to both techniques. Materials and Methods: This randomized comparative study was conducted at a tertiary care hospital from June to December 2023. Sixty patients aged 18–60 years were enrolled and randomized into two groups: Group P (PSO approach, n = 30) and Group T (TM approach, n = 30). Pre-procedural USG was performed to measure SED. Epidural blocks were subsequently performed using the landmark technique. Outcome measures included SED, number of attempts, need to change intervertebral space, and complications. Results: Demographic characteristics were comparable between groups. Mean SED was 3.75 ± 0.39 cm in Group P and 3.83 ± 0.47 cm in Group T ( P = 0.662). Most patients achieved successful epidural placement on the first attempt (96.7% in Group P, 90.0% in Group T; P = 0.612). Only one patient in Group P and two in Group T required a change of intervertebral space ( P = 1.000). No dural punctures occurred, and a single case of bloody tap was observed in each group. Conclusion: Both paramedian and transverse USG approaches provide comparable and reliable measurements of SED. They are equally effective in facilitating first-attempt epidural placement, with minimal complications, supporting their safe and interchangeable use in clinical practice.