Percutaneous nephrolithotomy (PCNL) is a safe and effective procedure that is considered the standard treatment for large and complex renal stones. Although it has lower complication and morbidity rates than open surgery, the pain and discomfort related to a nephrostomy tube can cause distress for patients.

Managing this pain with opioids can lead to sedation, nausea, vomiting, and constipation, which defeat the purpose of this minimally invasive procedure.

Skin infiltration with bupivacaine around the nephrostomy tube is not effective. Infiltration of renal capsule has shown to facilitate painless insertion of nephrostomy tube, suggesting the role of renal capsule in pain management.

Peritubal infiltration of bupivacaine from renal capsule to the skin along the nephrostomy tract may alleviate postoperative pain. A unilateral Low thoracic paravertebral (PVB) block offers the option of providing extendable perioperative pain relief without the above side effects or the physiologic derangement associated with local anesthetics in the central neuraxial space.

The aim of this study is to determine whether ultrasound guided low thoracic paravertebral block effective post-operative analgesia as compared to peritubal infiltration analgesia in patients undergoing percutaneous nephrolithotomy.

Main outcome measures: The primary endpoint is postoperative opioid consumption. Secondary endpoints are visual analogue pain scores, opioid related side effects.

Inclusion Criteria:

• American Society of Anesthesiologist's physiologic state I-III patients undergoing percutaneous nephrolithotomy

Exclusion Criteria:

• chronic pain
• bleeding disorders
• renal or hepatic insufficiency
• patients on chronic non-steroidal anti-inflammatory medications
• emergency cases