Following approval from the Institutional Ethical Committee, informed and written consent will be taken from 120 patients undergoing elective anorectal surgeries such as hemorrhoidectomy, fistulectomy, fissurectomy, perianal abscess, pilonidal sinus excision, etc.

A thorough preanaesthetic evaluation will be done 24 hours prior to the procedure. The study will include patients posted for anorectal surgeries. Standard monitoring with electrocardiography (ECG), automated noninvasive blood pressure (NIBP), and pulse oximetry (SpO2) using multipara meter Philips Intellivue MP20/MP30 monitor will be done for baseline values and intraoperative monitoring.

The 120 patients will be randomly divided into three groups using shuffled sealed opaque envelope technique. The anaesthesiologist who will be involved in randomization also will be preparing the studied drugs. He will not be involved further in the study.

Group BF â€“ 40 patients will receive 5mg 0.5%(H) bupivacaine(1ml) with Fentanyl 15mcgs(0.3ml) intrathecally.

Group BC-  40 patients will receive 5mg 0.5%(H) bupivacaine(1ml) with Clonidine 30mcgs(0.3ml) intrathecally.

Group C - 40 patients will receive 5mg 0.5%(H) bupivacaine(1ml) with 0.3ml normal salineintrathecally.

Total volume of drug for all the groups will be 1.3ml.

Patients will be seated at the operating bed and the skin will be prepared with a povidone-iodine solution. Spinal anesthesia will be performed at either the L3-L4 or L4-L5 interspace through a midline approach using a 25-gauge Quincke needle. After verification that the cerebrospinal fluid is freely flowing from the hub, the hole of the spinal needle will be pointed downwards, and then agents will be injected for about 10 seconds following gentle aspiration. After the injection, the patients will be seated for 10 minutes and will then moved to a lithotomy position.

An anesthesiologist will record the anesthetic data and vital signs. Levels of sensory and motor blocks will be checked immediately before the lithotomy position. The sensory level will beexamined by cold perception using alcohol-soaked gauze and the motor block level by a modified Bromage scale (0, no motor block; 1, can flex knee, move foot, but cannot raise leg; 2, can move foot only; 3, cannot move foot or knee). Adverse effects due to spinal anesthesia such as hypotension, bradycardia, nausea, vomiting, and pruritus will be recorded during surgery, at the post-anesthesia care unit, and in the general wards.

The numeric rating scale (NRS) pain score and adverse effects will be checked postoperatively every 2 hours for the first 12 hours and then every 4 hours for next 36 hours. The NRS pain score ranging from 0 (no pain) to 10 (the most severe pain that the patient had ever experienced) and the primary outcome variable will be the NRS score at six hours postoperatively. We will be defining a patient to be experiencing rebound pain if the patient previously does not have any pain or NRS <4 and reports acute pain or  NRS >7 within 1 hour. Secondary outcome variables will include NRS changes between one and 48 hours postoperatively, rescue analgesic consumption, and the frequency of rebound pain. Patients will not be given any rescue analgesics till they have any pain. Rescue analgesics will be given if the patient complains of pain or has NRS pain score more than 4. The first rescue analgesic to be administered will be paracetamol (15mg/kg I.V) and second rescue analgesic will be tramadol (1mg/kg I.V). The total consumption of rescue analgesics will be counted upto 48 hours postoperatively. An NRS elevation after reaching the maximal NRS score between one and 48 hours post-surgically during a decrease in pain is defined as rebound pain.