This study was designed to evaluate whether patient position (lateral vs. prone) has affect on the need for analgesia and onset of pain after surgery.

Percutaneous Nephrolithotomy is the preferred surgical treatment in many cases of kidney stones which is performed in different positions such as prone, lateral, and supine. However, we do not have enough evidence comparing prone and lateral positioning regarding the need for analgesia and onset of pain after surgery. This study was designed to evaluate whether patient position (lateral vs. prone) has affect on the need for analgesia and onset of pain after surgery.

Inclusion Criteria:

• Inclusion criteria were age between 18-65 years,
• having kidney stones; consent for spinal anesthesia,
• ASA classes (American Society of Anesthesiologists class) of 1 and 2 (patients without any cardiovascular or respiratory disorders)
• superior and median ureter larger than 20 mm in diameter.

Exclusion Criteria:

• those with coagulation defects,
• severe pain requiring more than one dose of fentanyl,
• considerable rise of blood pressure or heart rate during the operation.