Evaluation of Asymptomatic Microscopic Hematuria by Renal Ultrasound to Detect Upper Tract Malignancy: A 20-Year Experience in a Community Hospital

Abstract

Objective: To evaluate the sensitivity of ultrasound imaging in detecting upper urinary tract malignancy in patients with asymptomatic microscopic hematuria (AMH) in an outpatient community setting.

Materials and methods: A list of all patients who received renal ultrasound for hematuria in our health care system between January 1, 1997 and July 1, 2015 was obtained, and electronic health records were retrospectively reviewed. Patients were excluded for age (<18 years), <3 years follow-up, prior upper tract malignancy, recent urinary tract catheterization, inpatient status, pregnancy, insufficient data, or gross hematuria. The initial ultrasound was considered positive if suspicious findings led to a subsequent diagnosis of an upper tract malignancy. False negatives were determined by electronic medical record follow-up for at least 3 years.

Results: Of the 2138 patients with AMH who met inclusion criteria, ultrasound imaging detected suspicious findings in 9 of 9 patients with renal cell carcinoma and 3 of 3 patients with upper tract urothelial cancer, indicating a sensitivity of 100% and 100%, respectively. Four additional malignancies were diagnosed more than 3 years after the initial evaluation for an incidence rate of 1.6 cases of upper tract malignancy per 10,000 person-years.

Conclusion: The prevalence of upper urinary tract malignancy was low in patients with AMH. Ultrasonography is an appropriate modality for upper tract imaging in the initial evaluation of patients with AMH. Practice guidelines should be updated to reflect the high sensitivity of ultrasound and low risk of upper tract malignancy in patients with AMH.