Analgesic Efficacy of Ultrasound-guided External Oblique Intercostal Plane Block Versus Posterior Transversus Abdominis Plane Block in Patients Undergoing Open Nephrectomy

Renal cell carcinoma (RCC) accounts for 2-3% of all cancers and is a common malignancy of the genitourinary tract. Open nephrectomy, performed through midline, subcostal, or flank incisions, remains a standard treatment but often results in significant postoperative pain, leading to respiratory muscle dysfunction, increased pulmonary complications, and prolonged hospital stays. Acute surgical pain arises from inflammatory responses, activation of spinal pain pathways, and muscle spasms. While postoperative pain typically improves during recovery, some patients develop chronic postsurgical pain (CPSP), lasting at least two months postoperatively. Opioids and epidural analgesia are commonly used for pain control, but their side effects and invasiveness necessitate safer, effective alternatives. Ultrasound (US)-guided peripheral nerve and field blocks have become integral to multimodal an