A Head-to-Head Comparison: “Clean-Void” Bag Versus Catheter Urinalysis in the Diagnosis of Urinary Tract Infection in Young Children
Received 29 March 2004; received in revised form 8 April 2005; accepted 4 May 2005.
Objective
To compare the validity of the urinalysis on clean-voided bag versus catheter urine specimens using the catheter culture as the “gold” standard.
Study design
This is a cross-sectional study of 303 nontoilet-trained children under age 3 years at risk for urinary tract infection (UTI) who presented to a children's hospital emergency department. Paired bag and catheter specimens were obtained from each child and sent for dipstick and microscopic urinalysis. Sensitivity and specificity were compared using McNemar's χ2 test for paired specimens and the ordinary χ2 test for unpaired comparisons.
Results
The bag dipstick was more sensitive than the catheter dipstick for the entire study sample: 0.85 (95% confidence interval [CI]=0.78 to 0.93) versus 0.71 (95% CI=0.61 to 0.81), respectively. Both bag and catheter dipstick sensitivities were lower in infants ≤90 days old (0.69 [95% CI=0.44 to 0.94] and 0.46 [95% CI=0.19 to 0.73], respectively) than in infants >90 days old (0.88 [95% CI=0.81 to 0.96] and 0.75 [95% CI=0.65 to 0.86], respectively). Specificity was consistently lower for the bag specimens than for the catheter specimens: 0.62 (95% CI=0.56 to 0.69) versus 0.97 (95% CI=0.95 to 0.99), respectively.
Conclusions
Urine collection methods alter the diagnostic validity of urinalysis. These differences have important implications for the diagnostic and therapeutic management of children with suspected UTI.
From the Division of Pediatric Emergency Medicine, Department of Pediatrics, Department of Epidemiology and Biostatistics, and Clinical Research Centre, Montreal Children's Hospital, McGill University, Montreal, Quebec, Canada
Reprint requests: Dr. David McGillivray, Montreal Children's Hospital, 2300 Tupper Street, Room A-103, Montreal, Quebec, Canada H3H 1P3.
Presented in part at the annual meeting of the Pediatric Ambulatory Societies, Baltimore, Maryland, May 5, 2002.
Dr. Kramer is a Senior Investigator at the Canadian Institute of Health Research.
Supported in part by a grant from the Canadian Association of Emergency Physicians.
ABSTRACT