CT density – Is it a predictor in renal calculus clearance with extracorporeal shock wave lithotripsy

Background: Computed tomography of the kidneys, ureters and bladder (CT-KUB) is increasingly used for urinary lithiasis. Its higher sensitivity in detecting small, radiolucent calculi with the avoidance of intravenous contrast media is very beneficial and replacing the traditional intravenous urography. Materials and methods: A Prospective study at Gandhi Hospital, Hyderabed was conducted from August 2013 to January 2016. Study Group I: calculus CT density less than 900 HU and study Group II: calculus CT density more than 900 HU. Results: Most of the stones were located in lower calix, followed by renal pelvis in both the groups. Hematuria persisted more than 24 hours among 6 (6%) patients in group 1 while18 (22.5%) in group 2. Steinstrasse was seen in 8 patients among group 1 which was managed medically in 6 patients where as ureteric stenting required in 2 patients .Where it was 3 patients in group 2 among them 1 required ureteric stenting, which appears to be significantly low but it was not when calculated among successful fragmentation as it is secondary complication to fragmented caliculi drainage. Conclusion: In patients with CT density <900 HU the ESWL was successful in 88%, with 58% of the patients required only one session and two or three ESWL sessions in remaining; with mean no 1.58 ESWL sessions are required. In patients CT density >900 HU, ESWL was successful in fewer than half of the patients (44%), only13% of them in a single session, and 76% requiring three sessions with failure rate of 80% in that group.