Role of CT KUB in Extent and Severity of Hydronephrosis with Respect to Location and Size of Calculi

Abstract

Background: Hydronephrosis is a common condition caused by obstruction of urine flow, most frequently due to urinary tract calculi. Early and accurate diagnosis is essential to prevent renal damage and guide appropriate management. Computed Tomography of Kidneys, Ureters, and Bladder (CT KUB) is considered the gold standard imaging modality for detecting urinary calculi and assessing the extent and severity of hydronephrosis. Purpose of the Study: The aim of this study was to evaluate the role of CT KUB in determining the extent and severity of hydronephrosis with respect to the location and size of urinary tract calculi in patients. Methodology: A cross-sectional study was conducted at Faisal Hospital Lahore, enrolling 116 patients with suspected urinary tract calculi and hydronephrosis. CT KUB was performed using a multidetector CT scanner to assess stone size, anatomical location, Hounsfield Units (HU), presence of obstruction, and grading of hydronephrosis. Clinical history including flank pain, hematuria, and associated symptoms was also recorded. Hydronephrosis was graded from Grade 0 to Grade 4 based on severity. Data were analyzed using SPSS version 27, and the Chi-square test was applied to determine the association between stone size and hydronephrosis grade, with p<0.05 considered statistically significant. Results: The study population included 50.9% males and 49.1% females, with the majority of patients (37.9%) aged between 41–60 years. Left flank pain was the most common presenting complaint (47.4%), followed by right flank pain (39.7%). Hematuria was the most frequent associated symptom (32.8%). Most stones had attenuation values between 400–800 HU (41.4%), followed by 800–1200 HU (34.5%). Obstructive hydronephrosis was observed in 62.9% of patients, while non-obstructive hydronephrosis was present in 37.1%. Grade 1 hydronephrosis (40.5%) was the most common, followed by Grade 2 (26.7%). Smaller stones measuring 7–12 mm (34.5%) and 0–6 mm (33.6%) were more prevalent, whereas larger stones (19–25 mm) were less common (11.2%). Larger stones were mainly located in the renal pelvis and mid ureter and were associated with higher grades of hydronephrosis. However, the Chi-square test showed no statistically significant association between stone size and hydronephrosis grade (Pearson Chi-square = 59.097, p = 0.509). Conclusion: CT KUB proved to be a highly effective non-invasive imaging modality for identifying stone size, location, density, and severity of hydronephrosis. Although stone size showed no statistically significant association with hydronephrosis grade, larger stones and proximal locations were clinically associated with more severe obstruction. CT KUB remains an essential diagnostic tool for early detection, risk stratification, and management planning in patients with obstructive uropathy.