Cancer Diagnosis Program | Biorepositories and Biospecimen Research Branch

Search BRD Papers

Urine sampling in ambulatory women: midstream clean-catch versus catheterization.

Author(s): Walter FG, Knopp RK

Publication: Ann Emerg Med, 1989, Vol. 18, Page 166-72

PubMed ID: 2916781 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

   This study compared the diagnostic accuracy of midstream clean-catch urine for diagnosis of urinary tract infection (UTI) based on catheter urine. Pregnant women and those who had taken antibiotics in the previous 48 h were excluded. The periurethral area was cleaned by swabbing with three povidone-iodine-soaked gauze pads and a midstream urine specimen was collected. Immediately following collection of the mid-stream specimen, the patient was cleaned with povidone-iodine and catheterized by a nurse. Urine was cultured for 48 h before analysis. The catheterized specimen defined the presence of UTI.

   Summary of Findings:

   Concordant results were obtained using the catheter and clean-catch specimen in 80 of 105 cases (76%). Of the 25 cases with discordant results, 21 had contamination of the clean-catch specimen. The authors state that contamination would not lead to a diagnosis of UTI and therefore these patients would be considered clinically concordant, resulting in a clinical concordance rate of 96%. Identical results were found between the clean-catch specimen and catheter specimen for 40 of the 42 cases considered positive for UTI. The discrepancies in the positive cases included a clean-catch specimen that cultured a second bacterium not found in the catheter specimen and a clean-catch specimen that grew mixed flora, indicating contamination. Of the 61 cases where no growth occurred in the catheter specimen, 40 had no growth, 18 had mixed growth, three had low level growth (<10,000 cfu/mL) and two were false positives (>10,000 cfu/mL of a single species) in the clean-catch specimen.

   Overall, the sensitivity, specificity, PPV, and NPV of clean-catch specimens for diagnosis of UTI in the catheter specimen was 98%, 97%, 95%, and 98%, respectively.

   Biospecimens

   • Bodily Fluid - Urine

   Preservative Types

   • None (Fresh)

   Diagnoses:

   • Other diagnoses

   Platform:

   Analyte	Technology Platform
   Cell count/volume	Microbiological assay

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Biospecimen Acquisition	Method of fluid acquisition	Different urine collection procedures compared Needle Voided urine (spot collection)

   View more

2. Study Purpose

   This study compared concordance of leukocyte esterase, pyuria, nitrites, and microscopic observation of bacteria in 105 paired midstream clean-catch and catheterized urine and investigated the accuracy of each factor for diagnosis of UTI based on catheter urine. Pregnant women and those who had taken antibiotics in the previous 48 h were excluded. The periurethral area was cleaned by swabbing with three povidone-iodine-soaked gauze pads and a midstream urine specimen was collected. Immediately following collection of the mid-stream specimen, the patient was cleaned with povidone-iodine and catheterized by a nurse. Urine was analyzed within 1 h microscopically and by dipstick (Multistix dipsticks).  Pyuria was defined as > 5 WBC/high power field. Results of a 48 h culture of the catheterized specimen determined the diagnosis of UTI.

   Summary of Findings:

   Concordance between clean-catch and catheterized specimens was 83% (89 of 96 cases) for leukocyte esterase, 90% (94 of 105 cases) for pyuria, 90% (98 of 104) for nitrites, and 90% (94 of 105 cases) for microscopic bacteriuria. Basing diagnosis of UTI on culture of the catheter specimen, the use of leukocyte esterase for diagnosis resulted in a sensitivity of 75%, a specificity of 87%, a PPV of 77%, and a NPV of 85% in catheterized urine and a sensitivity of 80%, a specificity of 82%, a PPV of 72%, and a NPV of 89% in clean-catch urine. Sensitivity, specificity, PPV, and NPV of using pyuria for UTI diagnosis were 57%, 89%, 77%, and 76%, respectively, for catheterized urine and 71%, 86%, 77%, and 82%, respectively, for clean-catch urine. Use of nitrite results for UTI diagnosis resulted in a sensitivity of 34%, a specificity of 98%, a PPV of 93%, and a NPV of 70% in catheterized specimens and a sensitivity of 39%, a specificity of 98%, a PPV of 94%, and a NPV of 71% in clean-catch specimens. Significant microscopic bacteriuria (innumerable bacteria/high power field) as a diagnosis of UTI had a sensitivity, specificity, PPV, and NPV in catheterized urine of 33%, 100%, 100%, and 69%, respectively and 48%, 95%, 87%, and 73% in clean-catch urine, respectively. Importantly the sensitivity, specificity, PPV, and NPV of leukocyte esterase, nitrites, pyuria, and microscopic bacteria were not significantly different in catheter and clean-catch urine.

   Biospecimens

   • Bodily Fluid - Urine

   Preservative Types

   • None (Fresh)

   Diagnoses:

   • Other diagnoses

   Platform:

   Analyte	Technology Platform
   Cell count/volume	Light microscopy
   Small molecule	Colorimetric assay
   Cell count/volume	Microbiological assay

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Biospecimen Acquisition	Method of fluid acquisition	Different urine collection procedures compared Voided urine (spot collection) Catheterized urine
   Preaquisition	Diagnosis/ patient condition	UTI No UTI

   View more