Background and Objectives: Obesity presents signifcant challenges in neuraxial  anesthesia due to diffcult surface anatomical landmarks, leading to increased  failure rates and complications. Since Bier frst described spinal anesthesia in 1899, the traditional method for identifying the subarachnoid space has been through
anatomical landmarks. Conventional palpation techniques often prove unreliable  in these patients. Neuraxial ultrasound aims to enhance accuracy by visualizing  sonoanatomy, potentially improving success rates and patient outcomes. This  study was done to evaluate the effectiveness of preprocedural ultrasound-assisted
midline approach compared to the traditional landmark-guided technique in obese patients undergoing lumbar subarachnoid block.  Methods: A prospective observational study was conducted in 90 obese patients
(BMI > 25 kg/m²) aged between 18 and 80 years scheduled for elective surgery under spinal anesthesia at Travancore Medical College, Kollam. Patients were  divided into two groups: ultrasound-assisted (USG) and surface landmarkguided (SLG). Detailed history, physical examination, and informed consent were obtained. A portable USG machine with curved array probe was utilised for pre  procedure marking. Key variables measured included frst-attempt success rate, number of needle passes, time for space identifcation, and total procedure time. Data was analysed using statistical package for social sciences version 25.  Results: The frst-attempt success rate was signifcantly higher in the USG group (51.1%) compared to the SLG group (15.6%). The mean time for space identifcation was longer in the USG group (119.64 ± 48.69 seconds) than in the SLG group (28.56 ± 15.65 seconds), but the total procedure time was shorter in the USG group (281  ±85.657 seconds) compared to the SLG group (414.44 ± 218.835 seconds). Patient  satisfaction and reduced number of needle passes were also better in the USG  group. Conclusion: This study demonstrates that the ultrasound-guided technique   signifcantly improves the frst attempt success rate of spinal anesthesia and  enhances patient satisfaction in obese patients. Despite the longer time required  for space identifcation, the overall procedure time is reduced with ultrasound   guidance. These fndings suggest that incorporating ultrasound guidance into  clinical practice could enhance the effcacy of spinal anesthesia in obese patients,
highlighting its potential as a valuable tool in modern anesthetic practice.