LAS VEGAS — Although renal cortical scintigraphy remains the accepted standard for diagnosing pyelonephritis—with a sensitivity of 92% and a specificity of 100%—it's far from perfect, Dr. Melvin O. Senac Jr., said at a meeting sponsored by the American Academy of Pediatrics' California Chapters 1, 2, 3, and 4 and the AAP.
First, it's difficult to tell scars from pyelonephritis on renal cortical scintigraphy using dimercaptosuccinic acid (DMSA).
It's also expensive, around $700 per scan.
Finally, because renal damage is already done, the scan may not change the approach to managing these patients.
“The jury's still out on DMSA [scans],” said Dr. Senac, medical director and chief of radiology at Children's Hospital San Diego. “I wouldn't recommend it routinely.”
He went on to note that ultrasounds in children with clinical evidence of pyelonephritis are usually normal, and vesicoureteral reflux occurs 35%–40% of the time.
One episode of pyelonephritis produces a 10% chance of renal scarring, while four episodes result in a 58% chance of renal scarring.
In a study of 111 children with clinical findings of pyelonephritis, DMSA scans detected positive renal changes indicative of pyelonephritis in 67% of patients. The rest (33%) were normal (J. Pediatr. 1994;124:17–20). In addition, 64% of the patients had scarring at 1-year follow-up, and 39% had vesicoureteral reflux.
In light of the findings, the researchers recommended that all children with clinical signs of pyelonephritis undergo DMSA scans. However, Dr. Senac said that current medical evidence does not warrant such a practice.
“If I had data to support it, maybe I could recommend following this protocol, but as of 2006, I just can't,” Dr. Senac commented.
An “overlooked” way to diagnose pyelonephritis is by CT scan. “It's just as good as a DMSA renal scan,” he said. “I'm not advocating that, but it's easy when we have a child with right abdominal pain.”
He acknowledged that many questions exist about the best way to diagnose pyelonephritis and other urinary tract infections in infants.
“Is ultrasound necessary in the imaging workup? That really needs to be addressed once and for all,” said Dr. Senac, also of the department of radiology at the University of California, San Diego.
“Even more important, is there evidence-based value of prophylaxis in reducing reinfections and preventing renal scarring?” he asked. “That is a critical question. It needs to be a well-designed study with placebo control to see if prophylaxis is truly helping. We think it does, but there is not good evidence-based medicine on that.”