Ultrasound-guided Quadratus Lumborum Block Versus Erector Spinae Plane Block for Postoperative Analgesia in Children Undergoing Elective Open Lower Abdominal Surgeries

• ultrasound guided anterior oudratus lumborum block (Procedure): A high-frequency linear probe will be used to visualize the structures and a 22G, 80-mm echogenic needle will be inserted to deposit the drug. The probe will be placed above the iliac crest, and Petit's triangle will be identified. The three abdominal muscles (i.e., the external oblique, internal oblique, and transversus abdominus muscles) will be identified and will follow posteriorly until the layers of the Thoracolumbar Fascia (TLF) appeared as a bright hyper-echogenic line. The needle will be inserted in-plane along the posterior edge of the probe in anteromedial direction targeting the plane between the quadratus lumborum and psoas major muscle. After confirming the correct needle tip position and negative aspiration for blood, 0.5 mL/kg of 0.25% bupivacaine will be injected incrementally under real-time ultrasound guidance. The procedure will be repeated on the contralateral side.
• Ultrasound guided erector spinae plane block (Procedure): The patient will be placed in the prone or lateral decubitus position. The ultrasound probe will be positioned para-sagittally approximately 2-3 cm lateral to the midline at the T10-T12 vertebral level. The T11 transverse process will be identified deep to the erector spinae muscle complex. Using an in-plane caudal-to-cranial approach, a 22-gauge echogenic needle will be advanced until the tip contacts the transverse process. Following confirmation of correct plane by injection of 0.5-1 mL saline creating hydrodissection between the erector spinae and transverse process, 0.5 mL/kg of 0.25% bupivacaine will be injected incrementally. The procedure will be repeated contralaterally \].

Primary outcomes

• Time of first analgesic request [in the first 24 hours]

Secondary outcomes

• total opioid (fentanyl equivalent) consumption /ug [the first 24 hours postoperatively]
• postoperative pain intensity using the FLACC Scale (Face, Legs, Activity, Cry, Consolability) this scale range from 0to10 where 0 means no pain while 10 means worest untolerable pain [0, 30 minutes, 1, 2, 4, 6, 12, and 24 hours postoperatively.]: Interpreting the Score * 0: Relaxed and comfortable * 1-3: Mild discomfort * 4-6: Moderate pain * 7-10: Severe pain or discomfort

Sex: All, ages: 2 Years to 7 Years

Inclusion Criteria:

* Age: 2 to 7 years.
* ASA Physical Status Classification I or II .
* Scheduled for elective minor open lower abdominal surgery (bilateral inguinal hernia repair, orchiopexy, circumcision, bilateral hydrocele repair), pyeloplasty and ureteric reimplantation.
* Weight between 10 and 25 kg.

Exclusion Criteria

* Known allergy or hypersensitivity to local anesthetics (amide class).
* Contraindications to regional anesthesia: coagulopathy (INR > 1.5, platelets < 80,000/mm³), local infection at the injection site, or raised intracranial pressure.
* Pre-existing neurological, neuromuscular, or spinal disorders.
* Significant hepatic dysfunction (Child-Pugh Class B or C) or severe renal impairment (eGFR < 30 mL/min/1.73 m²).
* Previous abdominal or retroperitoneal surgery which likely to distort fascial planes at the injection site.
* Emergency or redo surgical procedures.
* Inability to assess postoperative pain due to pre-existing developmental or cognitive impairment preventing validated pain scale use.
* Intraoperative conversion from open to laparoscopic approach (post-randomization exclusion criterion).