Renal colic is a common problem and significant number of patients presenting to ER, ED are suffering from acute or chronic renal colic. The conventional methods of investigating patients with renal colic are urine routine examination, plain radiograph for KUB (kidneys, ureters and bladder) and ultrasound followed by intravenous urography. Now a days non contrast enhanced computed tomography of kidneys, ureters and bladder is the first line investigation in suspected upper urinary tract obstruction. Radiation dose is one of the major limitations of CT KUB. Other limitations are cost and availability. The sensitivity and specificity of CT KUB is extremely high in the diagnosis of stones.