The kidneys and ureters are the most prevalent sites for stones. The swelling of the kidneys due to renal stones, most often ureteric stones, is known as hydronephrosis. For detecting the position of stones, CT-KUB has a high sensitivity. Objective: To determine the frequency of obstructive and non-obstructive hydronephrosis due to calculi in CT-KUB. Methods: A cross-sectional study was conducted from January, 2022 to May, 2022 at Tertiary Hospital in Lahore, Pakistan. A sample size of 166 patients was obtained using a non-probability convenient sampling technique based on the previously published articles. All patients with renal calculi were included. 64 Slices Aquilian CT Machine was used. SPSS ver. 22 was used for data entry and analysis. Results: 166 Patients were in the age ranges of (15-25), (26-35), (36-45), (46-55), (56-65), and (66-75) were 27(16.3%), 39(16.3%), 32(19.3%), 37(22.3%), 22(13.3%), 9(5.4%) respectively. There were 126(75.9%) males and 40 (24.1%) females. Flank pain was present in 154(94%) and hematuria in 68(41%) patients. Stones were noted in kidneys 102(46.6%), proximal ureter 35(16%), mid ureter 21(9.6%), distal ureter 51(23.3%), urinary bladder 10(4.6%). 96 patients were diagnosed with obstructing hydronephrosis (57.8%). Conclusion: Urinary tract stones are most commonly seen in the kidneys and ureters. Obstructive and non-obstructive hydronephrosis is mostly caused by kidney stones. Obstructive hydronephrosis accounted for 57.8% of the total, whereas non-obstructive hydronephrosis accounted for 42.2%. CT-KUB plays a vital role in the diagnosis of hydronephrosis.
