Postoperative pain following abdominal hysterectomy is a challenging concern as some patients suffer acute pain that could let to chronic pain over time following the surgery. Epidural analgesia which is the gold standard for postoperative pain management in abdominal surgeries including abdominal hysterectomy has side effects such as hypotension, hematoma, motor weakness of lower limbs, paresthesia, intrathecal placement of the epidural catheter and urinary retention that could prolong hospital stay. Since high frequency ultrasound machines' usage has increased in postoperative analgesia management, ultrasound guided fascial plane blocks has been performed by clinicians with high success rate. To avoid possible complications of epidural catheter placement and epidural analgesia, various techniques has been applying for an analgesic effect close to the effectiveness of epidural analgesia. These techniques include transversus abdominis plane block, rectus sheath block, wound infiltration of local anesthetics, erector spinae plane block and quadratus lumborum plane block. However, each of the plane blocks has limitations individually which prevent them to be the unique analgesic technique for postoperative analgesia following abdominal surgery. As far as the authors knowledge, there's no reported study which compares ultrasound guided erector spinae plane block versus ultrasound guided quadratus lumborum type III block (anterior quadratus lumborum block) as a preemptive analgesia technique in patients undergoing abdominal hysterectomy.

Hysterectomy is one of the most frequently performed surgical procedures in the United States. The management of postoperative pain in gynecologic surgery is challenging.

Due to side effects of opioids such as nausea and vomiting, titration of opioid dosage for postoperative pain is difficult and effective postoperative analgesic regimes is needed. Ultrasound guided regional anesthesia techniques such as erector spinae plane block and quadratus lumborum block for postoperative pain management has an acceleration in usage as ultrasound guidance makes the interventions safer and easier to perform, and they contribute to better pain control and pain experience. Ultrasound guided quadratus lumborum block for postoperative pain management after abdominal surgery was firstly conceived by Blanco in 26th European Society of Regional Anesthesia Congress in 2007 as a variant of transversus abdominis plane (TAP) block. Later on he reported posterior quadratus lumborum block (QLB) in 2013 which is known as QLB II. Børglum et. al described the transmuscular quadratus lumborum block (TQL or QLB III) in 2013 which is frequently performed in abdominal wall surgeries. QLB III, transmuscular quadratus lumborum block (TQL) and anterior quadratus lumborum block; these are all synonyms and refers to injection of local anesthetic into the anterior thoracolumbar fascia (TLF) which lays between quadratus lumborum muscle and psoas major muscle. Erector spinae plane block has being performed by clinicians for abdominal and thoracic surgeries since it was firstly described by Forero et al. in 2016 for analgesia in thoracic neuropathic pain. In this ultrasound guided technique local anesthetic is applied between the transverse process of the relevant thoracic or lumbar vertebrae and the erector spinae muscle which leads to the spread of the local anesthetic cephalad, caudally and through the paravertebral space. The investigators hypothesize that performing ultrasound-guided quadratus lumborum block will be more superior or equal to erector spinae plane block in providing postoperative analgesia for patients undergoing abdominal hysterectomy under general anesthesia.

Inclusion Criteria:

• Patients who accepted to participate and signed written consent
• Aged between 18 and 75
• American Society of Anesthesiologists (ASA) physical score I or II
• Elective abdominal hysterectomy operation

Exclusion Criteria:

• Patients who declined to participate
• BMI > 35 kg/m2
• Uncontrolled systemic disease
• <18 age and >75 age
• Unable to cooperate (mental retardation)
• Low cardiac capacity
• Hypersensitivity history to the agents to be used
• Coagulopathy
• Local infections
• Opioid addiction history

Participant eligibility is based on self-representation of gender identity who will undergo abdominal hysterectomy operation.