The Case

The emergency department is getting busier with the after-work and after-school crowds. The next patient is a 5-month-old boy brought in by his parents because of a fever. The fever started that morning, and they kept him home from day care. The infant is immunized, looks well, and is drinking fluids in the department. Your examination does not indicate a source of infection. A urinary tract infection (UTI) is a possibility, but you know it could take a long time to get a noninvasive urine sample. In addition, bagged samples can often be falsely positive, and then you would need to get a urine sample using an invasive method such as a catheter. Could there be a way to increase the chance of getting a clean catch urine in fewer than five minutes?

Background

Urine samples are frequently required to rule in or rule out UTIs in children presenting to the emergency department with vomiting, fever, abdominal pain, and/or nonspecific illnesses.

The American Academy of Pediatrics (AAP) states that the diagnosis of a UTI requires a urinalysis and a urine culture. This comes from its 2016 clinical practice guidelines for the diagnosis and management of UTIs that reaffirmed earlier recommendations.¹

There are many reasons to rule in or rule out UTIs in children. These include the fact that missed UTIs can result in renal scarring and other pathology, appropriate antibiotic stewardship, and the avoidance of expensive and unnecessary imaging studies.

The AAP strongly recommends an invasive urine sample if the child looks unwell and requires antimicrobial therapy. The urine sample can be obtained with a suprapubic aspiration or urethral catheterization. Obtaining an invasive sample is a clinical decision.

The AAP also makes a strong recommendation that if the clinician determines that the febrile infant has a low likelihood of a UTI, then no urine testing is necessary as long as there is close clinical follow-up.

If the infant does not have a low likelihood of having a UTI but looks well, the AAP recommends two options: obtain the urine sample using one of the invasive method mentioned previously, or use a two-step approach to identify a UTI. The first step is to obtain a urine sample using a noninvasive method such as a bagged urine specimen. If the sample shows no evidence of a UTI, then cultures may be omitted. If the bagged sample shows evidence of a UTI, then the second step is to use an invasive method and perform a urine culture.

Clinical Question

In infants suspected of having a UTI, does the Quick-Wee method increase the success rate of getting a clean catch urine?

(click for larger image) Table 1: Secondary Outcomes of Quick-Wee Versus Usual Care for Urine Collection in Infants

Reference

Kaufman K, Fitzpatrick P, Tosif S, et al. Faster clean catch urine collection (Quick-Wee method) from infants: randomised controlled trial. BMJ. 2017;357:j1341.

• Population: Infants age 1–12 months in whom a urine sample was required and the clinician felt the appropriate method of collection was a clean catch urine.
  • Exclusions: Neonates and infants with neurological or anatomical abnormalities affecting sensation or voiding.
• Intervention: Quick-Wee method: Genital area was cleansed for 10 seconds with sterile water at room temperature. This was followed by continued rubbing of the suprapubic area in a circular pattern with gauze soaked in cold saline. A parent/clinician stood by for up to five minutes, ready to catch the urine sample.
• Comparison: Usual care: Genital area was cleansed for 10 seconds with sterile water at room temperature with a parent/clinician standing by, ready to catch the urine sample.
• Outcomes:
  • Primary: Proportion of subjects voiding within five minutes.
  • Secondary: Voiding with successful catch of urine sample, rates of contamination, and parental/clinician satisfaction with technique on a 5-point Likert scale.

Authors’ Conclusion

“Quick-Wee is a simple cutaneous stimulation method that significantly increases the five-minute voiding rate and success rate of clean catch urine collection.”

Key Results

There were 170 in the control group and 174 in the intervention group, totalling 344 subjects. It was evenly split between male and female infants, with the mean age being 5.4 months. The most common clinical indication for urine collection was fever (42 percent), followed by unsettled baby (38 percent). Only 17 percent of infants had urine collected because a UTI was specifically suspected.

• Primary Outcome: Voiding within five minutes (31 percent Quick-Wee versus 12 percent with usual care); an absolute difference of 19 percent (95% CI, 11%–28%). Number needed to treat was five.
• Secondary Outcomes: See Table 1.

Evidence-Based Medicine Commentary

Selection Bias: There may have been some selection bias. It appears that the patients were identified and recruited by the same emergency department that did the intervention.

External Validity: This was a single center, tertiary pediatric hospital in Australia and may not represent the same pediatric population presenting to pediatric, community, or rural emergency departments in the United States. Also, note that they also excluded neonates and those older than 12 months of age.

Statistical Significance: The sample size was calculated with 80 percent power to detect a difference of 15 percent between groups in the primary outcome. They did find a 19 percent difference, but the lower end of the 95 percent confidence interval was 11 percent.

Clinical Significance: The 15 percent difference was decided by consensus of 20 pediatricians and pediatric emergency medicine experts. However, others might consider a larger or smaller difference clinically significant.

Satisfaction Scores: The 5-point Likert scale they used was counterintuitive. They used 1 to mean “very satisfied” and 5 to mean “very unsatisfied,” which is opposite of the usual application of the tool.

Bottom Line: The Quick-Wee method can increase the success rate of getting a clean catch urine in infants suspected of having a UTI.

Case Resolution

You suggest to the parents using the Quick-Wee method to get a clean catch urine sample. After explaining how it is done, they agree. A few minutes later, you are sending off the sample to the lab for step one, urinalysis.

Thank you to Dr. Natalie May, an emergency physician with a subspecialty in pediatric emergency medicine and editor for the St. Emlyn’s blog and podcast.

Remember to be skeptical of anything you learn, even if you heard it on the Skeptics’ Guide to Emergency Medicine.

Reference

1. Subcommittee on Urinary Tract Infection. Reaffirmation of AAP clinical practice guideline: the diagnosis and management of the initial urinary tract infection in febrile infants and young children 2-24 months of age. Pediatrics. 2016;138(6). pii: e20163026.