Concerned parents have brought their 4-year old son to the ED with just over 24-hours of fever. History does not reveal a specific infectious focus. There is no vomiting, diarrhea, abdominal discomfort, or back pain. Hydration has been maintained. When asked about dysuria the patient giggles and hugs his mother instead of answering. His parents do not give any history of their child having complained of pain with urination. He is previously healthy, and uncircumcised. The nurse asks if you would like a urine sample sent to the lab. The dollar figures associated with unnecessary testing involuntary come to mind.
Urinary tract infections in children account for an estimated 5% to 15%
of pediatric emergency department visits in the United States. The diagnosis can be difficult to establish as the signs and symptoms at the time of presentation can be highly variable and nonspecific, especially in younger, non-verbal patients. While guidelines exist (NICE
) that provide physician guidance to the diagnostic process, there is often emphasis on urinary cultures as the gold standard diagnostic test. The difficulty, however, is that these culture results are usually unavailable at the time a child presents to an emergency department. Delays in the diagnosis of pediatric UTI can result in renal scarring
which can ultimately lead to hypertension and end-stage renal disease. A pragmatic approach to the diagnostic process in the emergency department that emphasizes appropriate early identification, balanced against the costs of indiscriminate testing, is required.
This JAMA Rational Clinical Examination systematically evaluated pediatric UTI diagnostic test characteristics for commonly obtained elements of the medical history, physical examination, and laboratory analysis. Based on prospective data provided by the 12 identified articles, the authors were able to calculate likelihood ratios for each step in the diagnostic process. These are mapped as suggested algorithms
to guide diagnosis while minimizing testing in situations where UTI is clinically unlikely (pre-test probability < 2%).
For infants (ages3-24 months), the following risk factors are considered:
- History of UTI
- Temperature > 39 C
- Ill appearance
- Suprapubic tenderness
- Fever >24h
- Nonblack race
In uncircumcised male infants, the baseline risk of UTI is around 6%. The presence of any of the aforementioned UTI risk factors is sufficient to raise this probability to between 10% and 25%, mandating further urinalysis and culture. In the absence of all the above factors, the risk falls to under 2%, and can be managed conservatively with reassessment in 24-hours.
In circumcised males the baseline risk is lower (around 1%) so two or more risk factors (or suprapubic tenderness alone) need to be present before further testing would be required. For female infants, the presence of any UTI risk factor is sufficient to raise the probability of UTI above the 2% threshold supporting urinalysis.
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Reprinted from Annals of Emergency Medicine, “Does This Child Have a Urinary Tract Infection?”, May 2009, Rupinder Singh Sahsi and Christopher R. Carpenter, copyright 2009, with permission from Elsevier
The algorithm is different for verbal children who present with urinary or abdominal symptoms. In circumcised males with a low baseline probability of UTI (<1%) urinalysis and culture is only recommended in the presence of multiple signs and symptoms of UTI. For females and uncircumcised males, the presence of dysuria/frequency OR the presence of abdominal pain, back pain, or new-onset incontinence is needed before diagnostic testing is mandated. In all other cases, UTI is considered highly unlikely. In this situation, alternative diagnoses should be contemplated while ensuring appropriate follow up.
While constructed in a logical and appropriate manner, this article’s Baysean approach is highly dependent upon the available evidence uncovered by their systematic search algorithm. Future prospective evaluation is needed before these recommendations can be deemed sufficiently validated to guide clinical decisions in the form of a stand-alone decision aid.
In this case, our young patient’s baseline risk of UTI as an uncircumcised male is estimated at around 8%, and would be increased by the presence of specific symptoms. In the absence of urinary frequency or dysuria, and lacking the other “higher-risk” symptoms (abdominal pain, back pain, or new-onset incontinence) the algorithm would suggest that UTI is unlikely. Since a urinalysis is unlikely to be diagnostic, you opt for symptomatic management of a likely viral illness. After ensuring appropriate follow-up is available you pat yourself on the back for achieving a small (but important and evidence-based!) fiscal victory.
Rupinder Sahsi, BSc MD is a faculty member and Technology Director of BEEM (Best Evidence in Emergency Medicine) and is an assistant clinical professor of emergency medicine at McMaster University. He practices in the emergency departments of Kitchener-Waterloo, Ontario, Canada.