Laparoscopic cholecystectomy although a minimally invasive procedure, may be accompanied by considerable pain after surgery. More recently transversus abdominis plane (TAP) block was extensively studied as a potential analgesic maneuver after laparoscopic cholecystectomy. The subcostal approach (OSTAP block) is a variation on the TAP block that produces reliable supraumbilical analgesia.

Laparoscopic cholecystectomy is a minimally invasive widespread surgical procedure, with postoperative lower pain scores and quick recovery of the patient. However some of patients may complain of considerable pain after surgery . There are several approaches to postoperative pain management after laparoscopic cholecystectomy such as patient-controlled analgesia with opioids (IV-PCA), neuraxial blocks, intraperitoneal injection of local anesthetics, wound infiltration, each being more or less effective, with specific side effects.

The transversus abdominis plane block (TAP-Block) is a regional analgesia technique that comes as an alternative to "classical" procedures of postoperative analgesia. Described by Rafi and McDonnell et al. this technique has undergone some changes over times, which increased its efficiency. Thus, Hebbard et al. described ultrasound subcostal oblique approach (OSTAP) of the block allowing analgesia in both the upper and lower abdomen, with a lower rate of complications due to the direct ultrasound visualization. Different studies confirmed the analgesic efficacy of this technique and the postoperative opioid sparing effect after laparoscopic cholecystectomy .

Traditionally, the transversus abdominis plane block is achieved with classical amino-amides local anesthetics, bupivacaine, levobupivacaine and ropivacaine being the most commonly used .

Based on the local anesthetic properties of pethidine, a synthetic opioid, our study aimed to evaluate prospectively the analgesic efficacy of pethidine in achieving transversus abdominis plane block by ultrasound oblique subcostal approach in patients scheduled for elective laparoscopic cholecystectomy.

Inclusion Criteria:

• American Society of Anaesthesiologists (ASA) I-II
• Age over 18years old
• patients scheduled elective laparoscopic cholecystectomy

Exclusion Criteria:

• Open cholecystectomy - excluded due to increased levels of pain in open procedures
• Renal dysfunction (Serum Cr > 1.2) - excluded due to potential altered metabolism of anesthetic and pain medications
• Coagulopathy or anticoagulation - increased risk of bleeding from nerve block injection
• Allergy or contraindication to any of the study medications or anesthetic agents
• Chronic opioid analgesic use at home - excluded due to potential difficulty in assessing pain caused by the procedure alone
• Patient inability to properly describe postoperative pain to investigators (language barrier, dementia, delirium, psychiatric disorder)
• Pregnancy
• Prisoners
• Patient or surgeon refusal