ORLANDO, FL USA (UroToday.com) - In the emergency setting, the use of urinalysis (UA) for patients with nephrolithiasis produces potentially confusing results.

In particular, the authors note that the presence of leukocyte esterase is non-specific for infection, because it likely represents ureteral inflammation from nephrolithiasis. In contrast, previous analyses have shown that UA findings of positive nitrites and > 5 white blood cells (WBCs) per high power field (hpf) on microscopy are more suggestive of pyuria in the setting of nephrolithiasis, and warrant treatment. In order to evaluate physicians’ treatment responses to these potentially conflicting lab findings, the authors attempted to evaluate the use of antibiotics in patients with nephrolithiasis.

auaThe authors performed a retrospective analysis of all ED visits within the Cleveland Clinic Northeastern Ohio health system by patients who received a CT scan-confirmed ICD-9 diagnosis of nephrolithiasis between 12/2010 and 4/2013 (a total of approximately 5 000 visits). The study data included assessment of urinalysis and the use of IV and PO antibiotics during the ED visit and at discharge. In accordance with previously established criteria, the authors defined appropriate criteria for antibiotic use as the presence of > 5 WBCs per hpf or positive nitrates. Serum WBC levels were also assessed in order to establish the presence of a systemic inflammatory response.

Urinalysis results were reported for 3 518 patients, which represented 70% of all ED patients with a diagnosis of nephrolithiasis during the study time period. Of these, 237 patients had positive nitrates (6.7%), and 864 had > 5 WBCs per hpf (24.6%). Only 158 patients (4.5%) had both findings. 314 patients (33.2%) received intravenous antibiotics; these patients had either positive nitrates or > 5 WBCs/hpf. Oral antibiotics were given to 731 patients (77.5%) with positive UA findings. Although 132/2 575 patients with a normal UA had elevated serum WBC, a significant proportion of the remaining 2 443 received IV (86, 3.6%) and PO (533, 21.8%) antibiotics at ED discharge.

Interpretation of the urinalysis in patients with nephrolithiasis lacks a clear standard, yet is vital to the correct implementation of antibiotic therapy in the ED. Although empiric IV antibiotics are commonly used, physicians should ensure that antibiotics are only administered when warranted. In this analysis, undertreatment (did not receive antibiotics when indicated) and overtreatment (received antibiotics when not indicated) were significant. Establishing a standard of care and improving education will improve this practice; further analyses are planned to determine how the role of the urologist (ED consultations, follow-up referrals) could improve this practice.

Presented by Benjamin Larson at the American Urological Association (AUA) Annual Meeting - May 16 - 21, 2014 - Orlando, Florida USA

Glickman Urological and Kidney Institute, Cleveland Clinics, Cleveland, OH USA

Written by Eric Ballon-Landa, BA , University of California (Irvine), and medical writer for UroToday.com


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