Combining kidney ultrasound with a visual examination of the bladder and urethra appears to be the most cost–effective way to screen for cancers of the genitourinary tract in people with microscopic amounts of blood in their urine, according to a study from Weill Cornell Medicine and NewYork–Presbyterian researchers.

The findings, published April 17 in JAMA Internal Medicine journal, challenge the current diagnostic recommendations, which call for computed tomography (CT) scan and cystoscopy.

Asymptomatic microscopic hematuria is a common condition in which patients have an invisible amount of blood in their urine that is detected only through a routine urinalysis. Up to 40 percent of Americans may test positive for the condition, and the vast majority of those cases are benign. But blood in the urine can point to something more serious in up to 10 percent of cases.

“The thing we are most concerned about with microscopic blood in the urine is the possibility of having cancer anywhere in the urinary tract, from the kidneys to the ureter to the bladder,” said lead author Dr. Joshua Halpern, a urology resident at Weill Cornell Medicine and NewYork–Presbyterian/Weill Cornell Medical Center.

The American Urological Association recommends that physicians further examine patients with the condition through a CT scan of the kidneys and ureters along with a cystoscopy, a procedure in which a small camera is inserted into the urethra and bladder to enable an evaluation of both for abnormalities. “The combination of CT scan and cystoscopy is effective but carries risks such as radiation exposure and urinary tract infections,” said study co–author Dr. Bilal Chughtai, an assistant professor of urology at Weill Cornell Medicine and a urologist at NewYork–Presbyterian/Weill Cornell. And, it’s costly. “The combination of possible health risks and the high costs create a barrier to appropriate evaluation,” Dr. Chughtai said.

In the study, Drs. Halpern and Chughtai, as well as senior author and former Weill Cornell Medicine researcher Dr. Hassan Ghomrawi, now associate professor of surgery and pediatrics at Northwestern University, sought to find out if other cancer screening methods for patients with microscopic blood in the urine were equally effective as the combination of CT scan and cystoscopy, without the potential side effects and expense. The study examined both the effectiveness and the costs of four different methods of screening for genitourinary cancer in patients who tested positive for blood in their urine: CT scan alone; cystoscopy alone; CT scan and cystoscopy combined; and renal ultrasound and cystoscopy combined.

They found that when both effectiveness and expense were considered, renal ultrasound combined with cystoscopy was the most cost–effective approach for evaluating patients with the condition, at an incremental cost of $53,810 per cancer detected compared with no evaluation at all. It was also effective at detecting cancer: this method identified 245 cancers in every 10,000 patients evaluated. CT scan and cystoscopy, the current gold standard, identified only one additional cancer, but at a much higher incremental cost of $6,480,484 per cancer detected.

He cautions that one size does not fit all when diagnosing cancer, however, and some CT scans will still be appropriate for some patients.