Laparoscopic appendectomy is the most frequently performed surgery in patients who develop acute appendicitis. This surgical technique is more advantageous than an open appendectomy in terms of fewer complications, less postoperative pain, and a faster return to normal daily activities. Even though the laparoscopic technique is minimally invasive, postoperative pain is inevitable. Furthermore, it may affect the patients' mobility and cause them to stay in the hospital for a more extended period .The study aimed to compare the effectiveness and the safety of ultrasound-guided erector spinae plane block versus ultrasound-guided transversus abdominis plane block (TAP) as postoperative analgesia methods after laparoscopic appendectomy.

Acute appendicitis develops in a progressive and irreversible manner, even if the clinical course of acute appendicitis can be temporarily modified by intentional medications. Reliable and real-time diagnosis of acute appendicitis can be made based on findings of the white blood cell count and enhanced computed tomography. Emergent laparoscopic appendectomy is considered as the first therapeutic choice for Acute appendicitis .

The reported advantages of laparoscopic appendectomy compared with open appendectomy are less postoperative pain, less wound infection, and better cosmetic results. Even though the laparoscopic technique is minimally invasive, postoperative pain is inevitable. Furthermore, it may affect the patients' mobility and cause them to stay in the hospital for a more extended period .An intraperitoneal injection of local anesthetics is one of the analgesic modalities that are used to control pain in such cases but it is insufficient analgesic in most of patients and has short duration effect .

Recently Ultrasound-guided nerve blocks were effectively used for postoperative analgesia in different types of surgical procedures .Both erector spinae plane block and oblique subcostal transversus abdominis plane block have been used effectively to reduce pain after laparoscopic appendectomy.

In ultrasound-guided Transversus Abdominis Plane (TAP) Block local anesthetic (LA) is deposited in the plane between the transversus abdominis and posterior sheath of the rectus muscle in approximately midway between the iliac crest and costal margin .To anesthetize The terminal branches of the lower six thoracic and first lumbar nerve lie within, providing analgesia of the anterior and lateral abdominal wall .This block has a low risk for serious complications such as bowel or diaphragm perforation and lacerations of the liver. Abdominal wall hematoma, vascular injury, and local anesthetic toxicity are also potential but rare complications . Owing to safety of ultrasound-guided needle placement a 'real-time' visualization through dynamic scanning is used .

The ultrasound-guided Erector Spinae Plane (ESP) block is a paraspinal fascial plane block in which local anesthetic is administered between the erector spinae muscle and the thoracic transverse processes at the levels of the T7-T9 transverse processes, resulting in spread between the T6 and T12 segmental levels, blocking the dorsal and ventral rami of the abdominal spinal nerves.

This blockage of the dorsal and ventral rami of the spinal nerves helps to achieve a multi-dermatomal sensory block of the anterior, posterior, and lateral abdominal walls.

ESP block Complications such as vascular puncture, pleural puncture and pneumothorax are the primary complications .Also local anethetic toxicity, infection at needle insertion site and allergy also can occur .

Inclusion Criteria:

• Patients scheduled for laparoscopic appendectomy,
• Patients aged 18-50 years,
• American Society of Anaesthesiologists (ASA) physical status I or II.

Exclusion Criteria:

• Declined informed consent.
• Allergy to local anesthetics.
• Conversion of the laparoscopic surgery to open appendectomy.
• Coagulation disorder.
• Pregnancy,
• BMI more than 40 kg/m2,
• Respiratory disease, liver or kidney disease; and heart disease (heart block, Rheumatic heart or myocardial ischemia).
• Psychiatric problems, that results in lack of communication ability.
• Chronic alcoholism, drug abuse,
• Infection in the area where the block will be applied.

- Patients will be allocated in two groups using computer-generated table by a person who has access to the computer-generated table but is not involved in data collection or patient management perioperatively. BLock will be given by Anesthesiologist who is not involved in the study.Data collection will be carried out by a person who is completely blinded to the randomization. The person who analyzed the data statistically will not be involved in randomization or data collection.