ROLE OF CONTRAST AND NON-CONTRAST COMPUTED TOMOGRAPHY IN EVALUATION OF OBSTRUCTIVE KIDNEYS

Background: Kidney obstruction is a significant contributor to renal dysfunction and preventable kidney failure, requiring timely and accurate diagnosis to guide effective management. Computed tomography (CT), particularly contrast-enhanced and non-contrast techniques, has emerged as a cornerstone in evaluating urinary tract obstruction due to its high sensitivity for detecting structural and pathological abnormalities. This study, conducted across multiple hospitals in Khyber Pakhtunkhwa (KPK), Pakistan, aimed to assess and compare the diagnostic performance of contrast and non-contrast CT in identifying the underlying causes of obstructive uropathy. Objective: To compare the effectiveness of contrast-enhanced and non-contrast CT in detecting key causes of obstructive kidney disease, including kidney stones, ureteropelvic junction (UPJ) obstruction, urinary tract infections (UTIs), hydronephrosis, cystitis, and narrowed ureters. Methods: A descriptive cross-sectional study was conducted from February to June 2022 on 141 patients referred for CT KUB due to suspected kidney obstruction. The sample consisted of 73 males (51.8%) and 68 females (48.2%), aged 12–90 years. Age groups included 48 patients (34%) aged 12–31, 56 (39.7%) aged 32–50, 22 (15.6%) aged 51–69, and 15 (10.6%) aged 70–90. Among all scans performed, 73 patients (51.8%) underwent contrast CT while 68 (48.2%) underwent non-contrast CT. Data were collected through structured questionnaires and imaging reports and analyzed to determine detection patterns for each abnormality. Results: Kidney stones were identified in 85 patients (60.3%), including 40 (47%) through contrast CT and 45 (53%) through non-contrast CT. UPJ obstruction was observed in 46 patients (32.6%), with 28 (60%) detected by contrast CT and 18 (40%) by non-contrast CT. UTIs were found in 84 patients (59.6%), with contrast CT identifying 44 (52%) and non-contrast CT identifying 40 (48%). Hydronephrosis appeared in 52 patients (36.9%), with 10 (20%) detected by contrast CT and 42 (80%) by non-contrast CT. Cystitis was diagnosed in 45 patients (31.9%), with 27 (60%) shown on contrast CT and 18 (40%) on non-contrast CT. Narrowed ureters were found in 34 patients (24.1%), including 24 (70%) detected by contrast CT and 10 (30%) by non-contrast CT. Conclusion: Contrast-enhanced CT demonstrated higher detection rates for most obstructive causes—including UPJ obstruction, UTIs, cystitis, and narrowed ureters—making it a more reliable modality for comprehensive evaluation of obstructive kidney disease. Non-contrast CT remained efficient for detecting kidney stones and hydronephrosis, supporting its role where contrast use is contraindicated.