Diagnostic Accuracy of Non-Contrast Computed Tomography in Identification of Renal Calculi in Suspected Patients with Negative Intravenous Pyelogram

Background: Renal calculi, commonly known as kidney stones, are mineral deposits found in the renal calyces and pelvis, either free or attached to the renal papillae. These stones can cause significant pain and health complications, making accurate diagnosis crucial. While intravenous pyelogram (IVP) has been a traditional diagnostic method, non-contrast computed tomography (NCCT) has emerged as a potentially superior alternative due to its higher sensitivity and specificity. Objective: To determine the accuracy of non-contrast computed tomography (NCCT) in identifying renal calculi in symptomatic patients with negative intravenous pyelogram (IVP) results. Methods: This cross-sectional study was conducted at the University of Lahore Teaching Hospital from August 7, 2023, to March 20, 2024. A total of 416 symptomatic patients, aged 19 to 49 years, with negative IVP results were included. Patients previously diagnosed with urolithiasis/nephrolithiasis by other imaging modalities, those who were uncooperative, pregnant, severely ill, or with congenital urinary tract abnormalities, were excluded. Demographic and clinical data were collected through interviews. Each patient underwent an NCCT scan, which was interpreted by an experienced radiologist. Data analysis was performed using SPSS version 25, with continuous variables summarized as means and standard deviations, and categorical variables as frequencies and percentages. Chi-square tests were used to assess associations, with a significance level set at p<0.05. Results: Of the 416 patients, 250 (60.09%) were diagnosed with urolithiasis/nephrolithiasis on NCCT, while 166 (39.90%) were negative. The majority of positive cases were male (n=156, 70.90%), with the most common age group being 19-29 years (n=91, 58.33%). The most frequent anatomical site for calculi was the ureter (n=151, 36.30%), followed by the kidneys (n=60, 14.42%) and the urinary bladder (n=39, 9.37%). The size of the single calculi varied, with the most common sizes being 0.4-0.5 cm (27.81%). Conclusion: NCCT demonstrated a significantly higher diagnostic accuracy for urolithiasis/nephrolithiasis compared to IVP. Given its superior sensitivity and specificity, NCCT should be considered the preferred diagnostic modality for patients presenting with acute renal colic and negative IVP results. These findings can improve patient outcomes through timely and accurate diagnosis, reducing the need for unnecessary diagnostic procedures.