High risk hematuria patients should be carefully investigated for any urinary tract diseases, especially malignancy or stones. The first-line imaging modality in real-world practice for patients with adequate renal function has always been intravenous urography (IVU), despite much discussion regarding the relative benefits of IVU as the first imaging test for hematuria. This study aims to investigate the diagnostic accuracy and alarm imaging features for predicting urinary tract malignancy on IVU by reviewing a database consisting of > 7000 patients.

This retrospective study was conducted in a single tertiary medical center under approval by institutional review boards at National Cheng Kung University Hospital (A-ER-114-207). We identified consecutive patients who had IVU from October 2008 to June 2023. We enrolled patients who had IVU before being diagnosed with malignancy and those who had a confirmed malignancy recurrence following IVU. It should be noted that the IVU results did not positively contribute to the diagnosis of malignancy; therefore, even though the IVU result was negative, some of these patients were later diagnosed with malignancy using other imaging modalities. The data including gender, age, symptoms, and IVU and pathological findings were analyzed. The main outcome was the diagnostic accuracy of individual alarm imaging feature.

A total of 261 malignant patients were included in the final analysis. Among all patients, 126 patients (48.3%) had a normal IVU, while the 135 patients (51.7%) had alarm features on the IVU and 102 patients (39.1%) were ultimately diagnosed with malignancy. Among 126 patients with a normal IVU, 44 patients (34.9%) were immediately found with malignancy via other imaging modalities due to a high clinical suspicion of malignancy, and the remaining 82 patients (65.1%) were later found to have malignancy unrelated to this IVU. 26 of the 135 patients with alarm features on the IVU had negative computed tomography (CT) and cystoscopic findings, while 7 patients had a positive CT result but underwent a thorough endoscopic examination to rule out malignancy. The pooled sensitivity and specificity of the alarm features were 69.9 % and 71.3%, respectively. 18 of the 103 patients had renal pelvis cancer, 38 had ureter cancer, and 46 had bladder cancer. Two of the main alarm features of bladder cancer were an irregular surface (30.4%) and a filling defect (80.4%). Additionally, 83.3% of cases of renal pelvic cancer had a filling defect. The features of ureter cancer were varied that 47.4% of cases had a filling defect, followed by obstructive hydronephrosis (21.1%) and non-enhancement (18.4%)

Although IVU was both moderate sensitive and specific, alarm features on IVU still provided predictive value for a potential malignancy; therefore, prompt endoscopy may be recommended for these patients.