Pediatric patients between the ages of 2 and 24 months who present with fever without a known source present a particular challenge because of the exceedingly nonspecific clinical presentation.¹ Asymptomatic bacteriuria and true urinary tract infections (UTIs) are often difficult to distinguish, which has led to overtesting, overdiagnosis, and overtreatment in otherwise healthy children.² In this column, I’d like to dispel some common myths and misperceptions about pediatric UTI that will better arm you to tackle this challenging problem. I’ll outline a standardized approach to pediatric UTI so that you know who to screen, how to screen, and what to do with the screen results, thereby reducing the risk of harm caused by excessive antibiotic use.

While observational data reveal that 7 percent of children 2 to 24 months of age presenting to the emergency department with isolated fever without an obvious source have a UTI, the prevalence of urosepsis in otherwise healthy, immunocompetent children has been estimated to be only 1 in 25,000.^3,4

The most important clinical predictors of UTI in the 2– to 24-month age group include temperature >40°C, fever >24 hours, suprapubic tenderness, jaundice, and, in males, lack of circumcision.¹ While “history of prior UTI” was shown to be predictive of UTI, it is important to recognize that prior false positives can be misleading, as earlier diagnoses may have been made speculatively without cultures or the culture results themselves may have been false positives. Placing patients in a high-risk category for UTI when they present with fever without a source based on a “history of UTI” is therefore a common pitfall that leads to overdiagnosis and overtreatment.

Negative predictors of pediatric UTI include an alternate obvious source of infection. A question that frequently arises is, does a febrile bronchiolitis presentation rule out UTI? A recent meta-analysis found the incidence of UTI in patients with bronchiolitis to be 0.8 percent, far lower than in previous studies suggesting testing for UTI in febrile bronchiolitis patients.⁵ It appears that most positive urine cultures in infants >2 months of age with bronchiolitis result from contamination or asymptomatic bacteriuria.

Urine specimen interpretation can lead to misdiagnosis. No single element of a urinalysis is sensitive enough to rule a UTI in or out; while nitrites are highly specific but not sensitive, leukocyte esterase is sensitive but not very specific.¹

UTI Calculator

A risk-stratification decision tool (https://uticalc.pitt.edu) has been developed to help physicians decide which infants 2–24 months of age require testing for UTI and which of those patients require treatment with antibiotics while cultures are pending.6 It involves a two-step process. In the first step, five questions are asked:

1. Age <12 months?
2. Maximum temperature ≥39°C (102.2°F)?
3. Self-described race as black (fully or partially)?
4. Female or uncircumcised male?
5. Other fever source identified?

If the calculator generates a score corresponding to a <2 percent risk for UTI, it indicates that no urine testing is required. When the generated score indicates higher risks, providers then must move to a second step, which assesses the subsequent urinalysis results. Based on the combination of the presence or absence of nitrites, leukocyte esterase, bacteria on Gram’s stain, and the white blood cell/mm3 concentration, the calculator generates a probability of UTI. When the calculated probability is <5 percent, no empiric antibiotics are required.

Sometimes, the decision hinges on the eventual culture results. Whether delayed treatment causes renal impairment and hypertension later in life is controversial. American Academy of Pediatrics (AAP) guidelines suggest that delays in appropriate treatment could increase the risk of renal damage.3 Some studies suggest that early antibiotic therapy within 72 hours is necessary to prevent renal scarring. However, these studies didn’t assess patient-oriented outcomes or long-term complications like chronic renal failure and hypertension. We simply do not know whether treating pediatric UTI prevents clinically relevant renal disease.

In higher-risk patients (>2 percent risk on step 1 of the UTI calculator) or in those who appear toxically ill, it may be appropriate to treat with antibiotics empirically. Always discuss the need to have the culture results reviewed to make the definitive diagnoses (and either continue therapy or stop it based on the culture results) with the family. If the patient is at lower risk (either <2 percent via step 1 of the calculator or <5 percent via step 2) and appears well, a watchful waiting approach whereby empiric antibiotics are not administered is reasonable.

How to Test the Urine

Once you’ve decided to order a urinalysis, the question is how best to obtain the sample. In the 2– to 24-month age group, the AAP guidelines suggest two options: obtain urine either through catheterization or suprapubic aspiration for culture and urinalysis or through the most convenient means to perform a urinalysis.³ If the urinalysis suggests a UTI (leukocyte esterase or nitrite test positive, or microscopic analysis results for leukocytes or bacteria), then a second urine specimen should be obtained through catheterization or suprapubic aspiration and cultured. Specimens obtained via urine bag have been shown to be effective to exclude UTI diagnosis; however, urine bags should not be sent for culture due to high risk of contamination.7 All positive urine bag dipsticks/urinalyses must be confirmed with a catheterized or midstream specimen before sending for culture.

As we all know, infants do not produce urine on command in the emergency department. To help speed up the clean catch process (while obtaining a sample less prone to contamination), two effective methods have been described. The Quick-Wee Method involves gentle suprapubic cutaneous stimulation (circular movement) using gauze soaked in cold fluid (for infants ages 1–12 months) until the clean catch urine is obtained.⁷

The Bladder Tap Technique involves three providers.8 The patient is fed 25 minutes prior. One provider gently taps the suprapubic area, at a rate of 100 taps per minute, for 30 seconds. The other provider then massages the lumbar paravertebral area in the lower back for 30 seconds. Both maneuvers are repeated until the third provider collects a clean catch urine sample.

There is little, if any, role for imaging in the emergency department for pediatric UTI. The latest AAP guideline no longer recommends voiding cystourethrograms after a single UTI. AAP and Canadian Paediatric Society guidelines both recommend children <2 years of age should be investigated with a renal bladder ultrasound after their first febrile UTI to identify any significant renal abnormalities (albeit a level C recommendation).^2,9 There is no convincing evidence suggesting that ultrasound improves patient-oriented outcomes, and ultrasound imaging may lead to further invasive testing that can cause harm.

My hope is that if we all think carefully about the predictive value of the clinical features of pediatric UTI, less unnecessary testing will occur. Consider using the UTI calculator and treating appropriately with antibiotics only when truly indicated and without imaging. By doing this, we can collectively reduce the harms that we are currently causing by overtesting, overdiagnosing, and overtreating pediatric UTI.

Special thanks to Dr. Michelle Science and Dr. Olivia Ostrow for their contributions to the EM Cases podcast that inspired this article. 

References

1. Shaikh N, Morone NE, Lopez J, et al. Does this child have a urinary tract infection? JAMA. 2007;298(24):2895-2904.
2. Alghounaim M, Ostrow O, Timberlake K, et al. Antibiotic prescription practice for pediatric urinary tract infection in a tertiary center [published online ahead of print Feb. 28, 2019]. Pediatr Emerg Care.
3. American Academy of Pediatrics, Subcommittee on Urinary Tract Infection, Steering Committee on Quality Improvement and Management, Roberts KB. Urinary tract infection: clinical practice guideline for diagnosis and management of the initial UTI in febrile infants and children 2 to 24 months. Pediatrics. 2011;128(3):595-610.
4. Morgenstern J. Articles of the month special edition: pediatric UTI. First10EM website. Feb 2, 2016. Accessed June 11, 2019.
5. McDaniel CE, Ralston S, Lucas B, et al. Association of diagnostic criteria with urinary tract infection prevalence in bronchiolitis: a systematic review and meta-analysis center [published online ahead of print Jan. 28, 2019]. JAMA Pediatr.
6. Shaikh N, Hoberman A, Hum SW, et al. Development and validation of a calculator for estimating the probability of urinary tract infection in young febrile children. JAMA Pediatr. 2018;172(6):550-556.
7. Kaufman J, Fitzpatrick P, Tosif S, et al. Faster clean catch urine collection (Quick-Wee method) from infants: randomised controlled trial. BMJ. 2017;357:j1341.
8. Tran A, Fortier C, Giovannini-Chami L, et al. Evaluation of the bladder stimulation technique to collect midstream urine in infants in a pediatric emergency department. PLoS One. 2016;11(3):e0152598.
9. Robinson J, Finlay J, Lang, M, et al. Urinary tract infections in infants and children: diagnosis and management. Paediatr Child Health. 2014;19(6):315-319.