Renal ultrasound is an appropriate modality for upper tract imaging in the initial evaluation of patients with asymptomatic microscopic hematuria (AMH), according to a new study.
In a study of 2138 patients with AMH who met inclusion criteria, renal ultrasound exhibited 100% sensitivity for detecting upper tract urothelial carcinoma (UTUC) and renal cell carcinoma (RCC), Matthew R. Smith, MD, PhD, of the Gundersen Medical Foundation in La Cross, Wisconsin, and colleagues reported in Urology.
The study population included patients who underwent renal ultrasound examinations for hematuria in the Gundersen health system from January 1, 1997 to July 1, 2015. The investigators defined microscopic hematuria as 2 urinalyses with 3 or more red blood cells per high-power field.
Of the 2138 patients in the study, 12 (0.6%) were diagnosed with upper tract malignancy (3 UTUC and 9 RCC) during their initial evaluation. All had an initial ultrasound examination positive for malignancy. Four additional upper tract cancers 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, according to Dr Smith and his colleagues.
“In conclusion, this work adds to the growing body of literature that supports renal ultrasound as an appropriate and effective method to evaluate for upper tract malignancy in patients with AMH,” the authors wrote.
Dr Smith’s team pointed out that the most recent (published in 2012) American Urological Association recommendations for managing patients with AMH states that computed tomography urography (CTU) with and without intravenous contrast is the imaging procedure of choice for evaluating upper urinary tracts in patients with AMH. “Given the low prevalence of malignancy in patients with AMH and high sensitivity of renal ultrasound support by the current study, the diagnostic benefit of CTU in this low-risk group is controversial.”
They also observed: “As the sensitivity of ultrasound approaches 100%, as measured by our study, CTU has diminishing benefit in detection of upper tract malignancies.”
Dr Smith and his coauthors pointed out that ultrasonography is widely available, noninvasive, and less expensive than CTU, and it spares patients ionizing radiation or IV contrast.
Smith MR, Read KC, Stegman M, et al. Evaluation of asymptomatic microscopic hematuria by renal ultrasound to detect upper tract malignancy: a 20-year experience in a community hospital. Urology. 2019; doi: 10.1016/j.urology.2019.07.009