Epidural anesthesia/analgesia can be performed under various positions. In this study, the investigators aimed to compare the intervertebral and skin-epidural distances in "the sitting" and "rider" positions with the help of ultrasonography

Complication rates in epidural intervention, which can be used for both intraoperative and postoperative analgesia are higher than peripheral blocks, especially in open abdominal surgeries. In epidural intervention, correct determination of patient position, puncture site and the distance from the skin to the epidural area (skin - epidural distance) is very important in terms of preventing complications. The location of the point where the epidural intervention will be made is aimed to be determined using the anatomical surface markings in the blind technique. However, anatomical surface markings are unreliable in pregnant or obese patients and patients with anatomical variants. The use of pre-procedure ultrasonography allows obtaining information such as midline and baseline determination, skin-epidural distance measurement, increasing the success of the intervention.

The most preferred positions for epidural interventions are sitting and lateral decubitus positions. Many modifications of these positions also exist. The rider position is used in a few centers in and out of Turkey, but there is only one clinical study related to the position.

Inclusion Criteria:

• ASA (American Society of Anesthesiologists) classification I-III

Exclusion Criteria:

• Prior spinal surgery
• Spinal deformity
• Recent spinal and head trauma
• Infection in the area to be measured
• Severe hypovolemia
• Severe edema
• severe abdominal distention
• Severe pain
• Difficulty in cooperation

The study is carried out in patients over 18 years of age who will undergo abdominal surgery, with ASA (American Society of Anesthesiologists) classification I-III.

We will share information about gender, age, height, body weight, ASA class, diagnosis, surgery, thoracic and lumbar intervertebral and skin-epidural distances measured in the rider and sitting positions