Strategies for Diagnosing UTI

Are there any historical or physical examination findings that can help emergency physicians make the diagnosis of UTI? Read the article and take the Quiz for 1 CME credit hour.

Educational Objectives:

After evaluating this article, participants will be able to:
1. Develop strategies for more accurate diagnosis of UTI in pediatrics using historical and physical examination findings
2. Incorporate into clinical practice a rational approach to diagnostics for the detection of UTI in pediatric patients

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Q. Are there any historical or physical examination findings that can help emergency physicians make the diagnosis of UTI?

A. While there is no single factor that can lead you in the right direction, the following risk factors can help:
1)Fever, particularly if it is higher than 40 C,
2)fever for more than 48 hours, 3)history of a previous UTI, 4)suprapubic tenderness, 5)dysuria, 6)increased frequency, 7)abdominal pain 8)back pain, 9)New onset incontinence and 10)lack of circumcision.

Citation:

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Shaikh N, Morone NE, Lopez J etal. Does this child have a urinary tract infection? JAMA. 2007 Dec 26;298(24):2895-904..

Objectives: To review the diagnostic accuracy of symptoms and signs for the diagnosis of UTI in infants and children.

Methodology: A search of MEDLINE and EMBASE databases was conducted for articles published between 1966 and October 2007, as well as a manual review of bibliographies of all articles meeting inclusion criteria, 1 previously published systematic review, 3 clinical skills textbooks, and 2 experts in the field, yielding 6988 potentially relevant articles.Studies were included if they contained data on signs or symptoms of UTI in children through age 18 years. Of 337 articles examined, 12 met all inclusion criteria. Two evaluators independently reviewed, rated, and abstracted data from each article.

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Findings: In infants with fever, history of a previous UTI (likelihood ratio [LR] range, 2.3-2.9), temperature higher than 40 degrees C (LR range, 3.2-3.3), and suprapubic tenderness (LR, 4.4; 95% confidence interval [CI], 1.6-12.4) were the findings most useful for identifying those with a UTI. Among male infants, lack of circumcision increased the likelihood of a UTI (summary LR, 2.8; 95% CI, 1.9-4.3); and the presence of circumcision was the only finding with an LR of less than 0.5 (summary LR, 0.33; 95% CI, 0.18-0.63). Combinations of findings were more useful than individual findings in identifying infants with a UTI (for temperature >39 degrees C for >48 hours without another potential source for fever on examination, the LR for all findings present was 4.0; 95% CI, 1.2-13.0; and for temperature <39 degrees C with another source for fever, the LR was 0.37; 95% CI, 0.16-0.85). In verbal children, abdominal pain (LR, 6.3; 95% CI, 2.5-16.0), back pain (LR, 3.6; 95% CI, 2.1-6.1), dysuria, frequency, or both (LR range, 2.2-2.8), and new-onset urinary incontinence (LR, 4.6; 95% CI, 2.8-7.6) increased the likelihood of a UTI.

Conclusion: Although individual signs and symptoms were helpful in the diagnosis of a UTI, they were not sufficiently accurate to definitively diagnose UTIs. Combination of findings can identify infants with a low likelihood of a UTI.

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Q. Are there any racial or ethnic considerations when diagnosing UTI?

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A.White and Hispanic patients are more likely than African American patients to have a diagnosis of UTI.

Citation #1

Chen L, Baker MD. Racial and ethnic differences in the rates of urinary tract infections in febrile infants in the emergency department. Pediatr Emerg Care. 2006 Jul;22(7):485-7.  

Objective: To characterize the racial and ethnic differences in rates of urinary tract infections among febrile infants who present to an urban pediatric emergency department.

Methodology: A retrospective chart review was conducted using the medical records of an urban pediatric emergency department from the period between 5/2002 and 1/2003. Data were collected from infants aged 1 to 24 months from whom urine cultures were obtained as part of their fever workup. Demographic data were recorded as provided by the parents or caregivers of the patients. Urine culture results were also recorded.

Findings: Four hundred and sixty five children had urine cultures performed during the study period and fulfilled the inclusion criteria. Parents characterized the children as white (45%), Hispanic (27%), African American (20%), Asian (3.9%), or others (4.3%). Clinical parameters including the height of fever, age of the patient, and proportion of men were similar between the subjects in each racial and ethnic group. Sixty-four children were diagnosed as having UTI. The overall prevalence of UTI was 14% (95% confidence interval [CI] 11%-17%). Rates of UTI (SD) were as follows: Asian 22% (10%), white 16% (2.4%), Hispanic 16% (3.1%), African American 4.0% (1.9%), and Others 11 % (6.2%). African American infants had a lower rate of UTI (p = 0.007) compared with the general population. The odds ratio (OR) of UTI in white versus African American children and Hispanic versus African American children were 4.4 (95% CI, 1.5 to 12.6) and 4.6 (95% CI, 1.5 to 13.9), respectively. These results were consistent after adjustment for sex.

Conclusion: Urinary tract infections were common in our study population of racially and ethnically diverse children. Given similar clinical parameters, white and Hispanic children were much more likely to be diagnosed with UTI than African-American children.

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Q. Does the duration of the fever help with the diagnosis of UTI?

A. Patients with fever duration of greater than 3 days had a higher positive bag and catheterized urine specimen culture rate.

Citation:

Bin Salleeh H, McGillivray D, Martin M, Patel H. Duration of fever affects the likelihood of a positive bag urinalysis or catheter culture in young children. J Pediatr. 2010 Apr;156(4):629-33. Epub 2009 Dec 21.

Objectives: To test the hypothesis that there will be a clinically significant rise in the proportion of positive bag urinalyses and catheter cultures in young children with increasing duration of fever.

Methodology: This was a prospective cohort study of 818 infants and children age 3-36 months presenting to a tertiary care emergency department with documented fever without source. Following the documentation of fever from or = 5 days, bag specimens were collected for urinalysis. The primary outcome was the yield of positive bag dipsticks by day, defined as positive for nitrates or more than trace leukocyte esterase. The secondary outcome was positive catheter cultures on each day of fever.

Findings: Positive bag urinalyses increased with duration of fever: 14.8% (35/237) on day 1 versus 26.4% (43/163) on day 3 (relative risk [RR] = 1.8; 95% confidence interval [CI] = 1.2-2.7; P = .004). Positive catheter cultures increased in the same fashion: 4.8% (11/229) on day 1 versus 12.6% (20/159) on day 3 (RR = 2.6; 95% CI = 1.3-5.3; P = .005)

Conclusion: The yield of positive bag urinalyses and catheter cultures increased significantly in children with fever of 3 days or longer duration

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Q. Are catheterized bladder specimens re
ally better than bag specimens?

A. Yes. Bag specimens result in both higher false positive and false negative rates.

Citation:

Etoubleau C, Reveret M, Brouet D, Badier I etal. Moving from bag to catheter for urine collection in non-toilet-trained children suspected of having urinary tract infection: a paired comparison of urine cultures. J Pediatr. 2009 Jun;154(6):803-6. Epub 2009 Apr 17.

Objectives: To compare, in the same children, urine culture results from bag- versus catheter-obtained specimens with catheter culture as the reference.

Methodology: A total of 192 non-toilet-trained children <3 years of age from 2 emergency departments were recruited for this prospective cross-sectional study. All had positive urinalysis results from bag-obtained specimens that were systematically checked with a catheter-obtained specimen before treatment. Results of comparison of urine cultures obtained with these 2 collecting methods are presented.

Findings: A total of 7.5% of bag-obtained specimen positive cultures had false-positive results. Twenty-nine percent of bag-obtained specimen cultures with negative results were false negative. Altogether, bag-obtained specimens led to either a misdiagnosis or an impossible diagnosis in 40% of cases versus 5.7% when urethral catheterization was used.

Conclusion: Every bag-obtained positive-result urinalysis should be confirmed with a more reliable method before therapy.