Percutaneous nephrostomy (PCN) is one of the interventions in the radiology department in which pain control is necessary. Quadratus Lumborum (QL) block will be tried to limit the use of systemic analgesics and its accompanying untoward effects in those frail patients requiring PCN that is performed in the prone position.

Quadratus Lumborum block is a novel technique in which extension into the thoracic paravertebral space may occur. QL block would seem to be able to alleviate both somatic and visceral pain so it's expected to decrease the need for systemic sedation\analgesia to a minimum.

Inclusion Criteria:

1. ASA grade III and IV patients,
2. Ureteral obstruction due to malignancy or secondary to urinary diversion after cystectomy

Exclusion Criteria:

1. Bleeding diathesis; INR more than than 1.5 and platelet count less than 100,000/mm3.
2. Untreated urinary tract infection;
3. Pre-operative haemoglobin <10 gm/dl,
4. Severely co morbid patients
5. Non-dilated renal collecting system
6. Patient refusal to consent for the procedure.