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Is Renal Ultrasound Enough? Risk for Abnormal DMSA Despite Normal Renal Ultrasonography After One Febrile UTI

Sunday, October 21, 2012: 9:59 AM
Grand Ballroom B (Hilton Riverside)
Nicol Corbin Bush, M.D.1, William A. Smith1, Janelle Traylor2, Karen Pritzker2, Anjana Shah2, Carlos A. Villanueva, MD1 and Warren T. Snodgrass, M.D.1, (1)Pediatric Urology, Children's Medical Center, Dallas, TX, (2)Pediatric Urology, Children's Medical Center Dallas, Dallas, TX

Purpose:

The American Academy of Pediatrics released new guidelines suggesting renal ultrasound (RUS) as the only evaluation after initial febrile UTI in infants aged 2-24 months, which will delay the diagnosis of vesicoureteral reflux (VUR). However, VUR is associated with a higher risk for renal scarring, and some patients with a normal RUS may have renal damage that can be detected with DMSA. We evaluated the risk for DMSA-detected abnormalities (diminished function +/- scar) in patients aged 2-24 months with normal RUS after a febrile UTI, as well as those >24 months anticipating that pediatricians may extend the guidelines to older patients.

Methods:

Consecutive patients referred with a history of a single febrile UTI underwent DMSA >3 months after the infection in addition to their baseline RUS. Data including gender, age, #UTIs, and RUS and DMSA results were prospectively recorded. Patients with solitary kidney, neurogenic bladder, valves, exstrophy, UPJ, UVJ, ureterocele, and/or ectopic ureter were excluded. Abnormal RUS was defined as any hydroureteronephrosis, renal cortical defects, or size asymmetry >1cm. Abnormal DMSA was defined as presence of ipsilateral diminished function <45% and/or any focal cortical uptake defects. VCUG was recommended in patients with abnormal DMSA.

Results:

Of 344 consecutive patients with a single febrile UTI (77.9% female, median age 18.5 months), 268 had normal RUS. Of these, 13.4% had diminished function +/- scar on DMSA.

Age ≤24 months: Of 146 patients with normal RUS, 12 (8.2%) had abnormal DMSA, of whom 11/12 (91.7%) had VUR, ranging from grades 1-5 in 1, 2, 4, 3, and 1, respectively.

Age >24 months: Of 122 patients with normal RUS, 24 (19.7%) had abnormal DMSA, of whom 18/22 (81.8%) who underwent VCUG had VUR, ranging from grades 1-4 in 1, 7, 6, and 4, respectively.

Conclusion:

Renal damage (diminished function +/- scar) after one febrile UTI was detected by DMSA in 13.4% of patients despite normal renal ultrasound. VUR was present in 85% of these children. By the current AAP guidelines for 2-24 month-olds with febrile UTI, 1 out of every 12 patients with an abnormal DMSA, potentially at risk for further renal damage, will be missed by RUS alone. If primary care providers expand the current guidelines to patients older than 2 years, 1 in 5 patients could be missed by RUS alone. In addition to RUS after febrile UTI, we recommend non-acute DMSA (and VCUG when abnormal) in order to identify patients at risk for additional renal damage who might benefit from earlier diagnosis and therapy when VUR is identified.