Nawaz Rashid, Zia-ur Rehman, Iqbal Hussain Dogar, Kamran Sajjad Hashmi, Fareeha Nawaz.
Predictability of Computerized Tomography as Compared to Ureteroscopy in Detection of Ureteric Stone in patients with Indwelling Stents.
Ann King Edward Med Uni Jan ;28(2):175-9.

Objective: The current gold standard for the diagnosis of ureteric stones in patients with a stent in situ is ureteroscopy but this study is planned to determine the positive predictive value of computerized tomography (CT) scan among such patients. Methods: This study involved patients who had ureteral stent in situ and were referred for re-evaluation of residual stones after extracorporeal shock wave lithotripsy. These patients underwent CT-scan for detection of ureteric stone. Later on, ureteroscopy was performed and ureteric stone was confirmed on direct visualization. Results: The mean age of the patients was 32.2+-8.9 years. Male to female ratio of 1.7:1. CT scan shows a stone in 252 patients (70.2%) out of which 165 (46.0%) were confirmed on ureteroscopy. This yielded a sensitivity of 88.7 %, specificity of 49.7 %, positive predictive value of 65.5%, negative predictive value of 80.4% and diagnostic accuracy of 69.9% of CT for detecting ureteric calculi in patients with ureteric stents (p value < 0.0001). Conclusion: CT scan owing to its limited diagnostic accuracy cannot replace ureteroscopy for detection of ureteric stones in patients with ureteric stents.

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