Patients will be allocated into two groups using computer generated numbers. Each group will be comprised of 40 patients. The primary investigator of the study will be blinded to the treatment.

 Group 1- Lateral Quadratus lumborum block.

 Group 2-Posterior Transversus Abdominis Plane block.

Routine pre-anaesthetic evaluation will be done and the patients will be kept nil per oral for 6 hours prior to surgery. On arrival at operation theatre standard anesthesia monitors including non-invasive blood pressure (NIBP) , electrocardiogram (ECG) and pulse oximetry will be attached and baseline hemodynamic parameters will be noted.

For the ultrasound guided QLB group, the patient will be placed in supine position, and skin sterilizations will be performed with antiseptic solution and draped. A high-frequency linear probe will then be placed above the iliac crest in the area of triangle of petit, to identify three layers- 3 abdomen barrier muscles. First, transverse abdominis will be outlined posteriorly till the transverse aponeurosis appears.  Next, QL will be recognized medial to the aponeurosis of transverse abdominal muscles. The 20G needle will then be injected from superofrontal to posteroinferior and progressive via the inplane method till the needle tip touches the anterolateral edge of the QL at its junction with the transversalis fascia. After negative aspirations (to reject intravascular injections), 1 mL of normal saline will be injected to confirm the position of the needle. After confirming the position of the needle, a bolus dose of 0.125% bupivacaine 0.5ml/kg will be injected. The same method will be performed on the other side also. On ultrasound, the distribution of local anaesthetic agent will be observed as a hypo-echoic enlargement beneath transversus abdominis aponeurosis.

For posterior approach TAP block, patients will be placed in supine position, the anterolateral abdominal wall on both sides will be prepared with antiseptic solution and draped. Ultrasound probe will be placed in flank region between anterior superior iliac spine and costal margin. The External Oblique, Internal Oblique and Transversus abdominis identified.  The 20 gauge intravenous cannula will be advanced in the plane in anterior direction. After placement of the cannula between Internal Oblique and Transversus abdominus, 1ml of normal saline will be injected to confirm the placement of needle. After confirming the position of the needle, a bolus dose of Inj 0.125% bupivacaine 0.5ml/kg will be injected on both sides. On ultrasound, the distribution of local anaesthetic agent will be observed as a hypo-echoic enlargement between the fascial planes as a real time image.

 After performing the respective blocks, inhalational agent will be discontinued. Extubation will be done after complete recovery assessed by clinical observation and neuromuscular monitoring. Reversal of neuromuscular blocking agent will be done with Inj.Neostigmine 0.5mg/kg and  Inj.Glycopyrrolate 10 mcg/kg.

 Haemodynamic parameters like heart rate, systolic blood pressure, diastolic blood pressure, mean arterial pressure, SPO2 will be recorded in fifteen minutes, thirty minutes, sixty minutes, two hours, four hours, eight hours, twelve hours, twenty four hours post operatively. Pain will be assessed using MOPS scale, with zero representing no pain and ten representing worst pain. Patients receive Inj. Tramadol 1mg/kg IV as rescue analgesic.

 Patients will be assessed for time to first rescue analgesia as the time interval between the end of block performance and first demand by patient for rescue analgesia. The total amount of rescue analgesia is described as total dose of Tramadol (1mg/kg) required in 24 hours since the end of block performance. Side effects if any will be recorded.