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Pediatrics, Urinary Tract Infections and Pyelonephritis: Differential Diagnoses & Workup

Author: Stephen L Thornton, MD, Attending Physician, Department of Emergency Medicine, St John's Hospital
Contributor Information and Disclosures

Updated: Dec 17, 2008

Differential Diagnoses

Pediatrics, Appendicitis
Urinary Obstruction
Pediatrics, Bacteremia and Sepsis
Vaginitis
Pediatrics, Fever
Vulvovaginitis
Pediatrics, Gastroenteritis
Wilms Tumor
Pinworms
Renal Calculi
Urethritis, Male

Other Problems to Be Considered

Cystitis
Pregnancy
UTIs
Urolithiasis
Vesicoureteral reflux

Workup

Laboratory Studies

  • The criterion standard for diagnosing urinary tract infections (UTIs) is the isolation of a pathogen from a urine culture obtained via suprapubic aspiration.
  • While suprapubic aspiration is the criterion standard method for obtaining urine, catheterization is the most commonly used technique in infants and younger children. More than 50,000 CFU/mL in a catheterized specimen is defined as a UTI, though some experts recommend 10,000 CFU/mL as the cutoff.
  • Midstream clean catch urine specimens are also adequate for older children who can provide them. More than 100,000 CFU/mL in a midstream clean catch urine specimen is defined as a UTI.
  • Bagged urine specimens are of no value for the diagnosis of UTIs due to high rates of false-positives, and their use should be discouraged.
  • Although urine culture is the criterion standard for diagnosis UTIs, it may take up to 48 hours for cultures to be positive. Therefore, evaluation of urinalysis is often needed to help make the initial diagnosis of a UTI.
    • A urine specimen that is found to be positive on dipstick for nitrite, leukocyte esterase, or blood may indicate a UTI.
    • Dipstick tests have sensitivities approaching 85-90%.
    • Microscopic examination of spun urine can evaluate for presence of WBCs, RBCs, bacteria, casts, and skin contamination (eg, epithelial cells).
    • With regards to a suprapubic aspirate, 5 or more WBC/high power field suggests an infection.
    • Hemacytometer measures cells per volume and has been found to be more sensitive and specific than standard microscopic examination.1,2
    • With regards to a suprapubic aspirate, 10 or more WBC/μL is consistent with infection.1,2
    • Gram stain of unspun urine may show organisms.
    • A combination of hemacytometer cell count and Gram stain has been shown in studies to have a sensitivity approaching 95%.
  • In pediatric patients, urine cultures should be sent to the laboratory even if urinalysis results are inconclusive.
    • Approximately 10-20% of pediatric patients with UTIs have normal urinalyses results.
    • Multiple organisms may be present if structural abnormalities exist.
  • Hematological studies do not tend to help in the diagnosis of UTIs, though they should be obtained in patients that appear ill.
  • In suspected bacteremic/uroseptic patients, blood cultures should be obtained.
  • Renal function can be measured by serum Cr and BUN levels and may be elevated in severe disease.
  • Electrolyte abnormalities may be present.

Imaging Studies

  • Imaging is recommended by the American Academy of Pediatrics for patients 2 months to 2 years old with febrile UTIs.
  • The recommendation is for a renal ultrasonography and a voiding cysto-urography (VCUG). The purpose is to identify those with vesicoureteral reflux (VUR).
    • Renal ultrasonography allows for the identification of anatomical abnormalities (ie, duplication) and hydroureter/nephrosis. It does not allow for definitive diagnosis of VUR, though it can suggest it.
    • VCUG allows for anatomical definition of urethra and bladder and grading of VUR, if present.
  • Though still the standard of care, many question the utility and effectiveness of the current imaging recommendations, especially in light of recent trends to minimize exposure to ionizing radiation.
  • Neither renal ultrasonography nor VCUG can evaluate for pyelonephritis or renal scarring, which could lead to long-term complications.
  • Tc 99m dimercaptosuccinic (DMSA) is the criterion standard to detect pyelonephritis and renal scarring.
    • DMSA involves injecting a radionuclide that binds to renal proximal tubular cells.
    • Decreased uptake represents abnormal or damaged cells.
    • Some experts recommend screening with DMSA during the acute UTI with the reasoning that if there is no kidney involvement during the acute phase there is no risk of renal scarring and further complication and no need for further imaging.

Procedures

  • Transurethral catheterization of the urinary bladder is the most common procedure performed in the evaluation of UTIs. There is a risk of introducing pathogens with catheterization.
  • A suprapubic bladder aspiration may also be performed to obtain urine and is the criterion standard despite the potential for gross or microscopic hematuria. Risk of infection is lower than with transurethral catheterization, and complications are low. 

More on Pediatrics, Urinary Tract Infections and Pyelonephritis

Overview: Pediatrics, Urinary Tract Infections and Pyelonephritis
Differential Diagnoses & Workup: Pediatrics, Urinary Tract Infections and Pyelonephritis
Treatment & Medication: Pediatrics, Urinary Tract Infections and Pyelonephritis
Follow-up: Pediatrics, Urinary Tract Infections and Pyelonephritis
References
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References

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Further Reading

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Keywords

UTI, urinary tract infection in kids, urinary tract infection in infants, UTI in children, cystitis, UTI in infants, urosepsis, pyelonephritis, cystitis, vaginitis, bacterial infection

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Contributor Information and Disclosures

Author

Stephen L Thornton, MD, Attending Physician, Department of Emergency Medicine, St John's Hospital
Stephen L Thornton, MD is a member of the following medical societies: American College of Emergency Physicians and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Medical Editor

David S Howes, MD, Residency Program Director, Professor of Medicine, Section of Emergency Medicine, University of Chicago/Pritzker School of Medicine
David S Howes, MD is a member of the following medical societies: American College of Emergency Physicians, American College of Physicians-American Society of Internal Medicine, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Pharmacy Editor

Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine
Disclosure: Pfizer Inc Stock Investment from financial planner; Avanir Pharma Stock Investment from financial planner ; WebMD Salary and stock Employment and investment from financial planner

Managing Editor

Grace M Young, MD, Associate Professor, Department of Pediatrics, University of Maryland Medical Center
Grace M Young, MD is a member of the following medical societies: American Academy of Pediatrics and American College of Emergency Physicians
Disclosure: Nothing to disclose.

CME Editor

John D Halamka, MD, MS, Associate Professor of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center; Chief Information Officer, CareGroup Healthcare System and Harvard Medical School; Attending Physician, Division of Emergency Medicine, Beth Israel Deaconess Medical Center
John D Halamka, MD, MS is a member of the following medical societies: American College of Emergency Physicians, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Chief Editor

Richard G Bachur, MD, Associate Professor of Pediatrics, Harvard Medical School; Associate Chief and Fellowship Director, Attending Physician, Division of Emergency Medicine, Children's Hospital of Boston
Richard G Bachur, MD is a member of the following medical societies: American Academy of Pediatrics, Society for Academic Emergency Medicine, and Society for Pediatric Research
Disclosure: Nothing to disclose.

 
 
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