Urine transparency as an index of absence of infection

Comparison of 2 techniques used to obtain sterile urine specimens from urethral catheters

OBJECTIVE

The objective of this study was to compare the rates of urine contamination and the frequencies of minor adverse events between the vacuum tube and injector techniques methods for the collection of sterile urine specimens.

DESIGN

This study was a cross-sectional study.

SAMPLE

The sample population was composed of patients who underwent a urodynamics procedure.

SETTING

This study was performed at the urodynamics unit of a rehabilitation and care center in Turkey.

METHODS

Sterile urine specimens (n = 576) were collected from 144 patients using the vacuum tube technique and the injector technique; the rates of urine contamination and minor adverse events were evaluated. χ2 Statistics and Fisher exact tests were used to assess the contamination rates and frequencies of minor adverse events during the collection of sterile urine specimens.

RESULTS

The contamination rate of urine specimens collected using an injector was 0.9% (P > .05). The rate of minor adverse events during specimen collection was lower when using the vacuum technique than when using an injector and sterile urine container (2 vs 36 events, P < .05).

CONCLUSION

The vacuum tube technique of urine specimen collection was not superior to the injector technique in regard to contamination. The use of the vacuum tube technique for the collection of sterile urine specimens can prevent minor adverse events related to spillage/leakage of urine.

IMPLICATIONS

More research from multiple settings and work environments is needed to strengthen the evidence base of vacuum tube technique of sterile urine specimen collection.

Can community-dwelling women reliably identify infected urine?

The purpose of this study was to evaluate whether community-dwelling women can reliably identify infected urine samples. A convenience sample of 25 women judged six urine samples. Of these, two were normal, two contained culture-proven infections, and two were intentionally abnormal because of ingestion of asparagus or vitamins. The women decided if each sample was infected based on its color, clarity, and odor. For the two normal samples, 56 and 96% women correctly identified them. Of the two samples positive for infection, women were correct 80 and 100% of the time. Of the two samples designed to be abnormal, women were correct in 92 and 64% of their evaluations. Using the 150 total evaluations of urine samples, the sensitivity was 90%, and the specificity was 77%. Based on this small sample, community-dwelling women can detect infected samples of urine. However, women should still be screened for factors that might have distorted normal urine.

A comparison of chemical dipsticks read visually or by photometry in the routine screening of urine specimens in the clinical microbiology laboratory

Two different commercially available urine dipsticks were evaluated to determine their usefulness as a screening test for the detection of non-infected urine specimens. The reactions of both dipstick strips were read visually and, in addition, one was read by semi-automated reflectance photometry. 2928 consecutive routine urine specimens received by the microbiology laboratory during normal working hours underwent testing by the conventional method of microscopy and culture and the results were compared with those obtained by dipstick testing. There were poor correlations between microscopy for red and white blood cells and dipstick results for blood and leucocyte esterase respectively. The dipsticks had a low positive predictive value (PPV) in identifying infected urines. In contrast, dipsticks had a very high negative predictive value (NPV) of 98.6-99.5% and correctly identified a significant proportion (about 1/3) of non-infected urines as reported by the conventional method. Introduction of dipstick testing of urine specimens in our hospital has led to significant time saving as dipstick-negative urines are not processed further (except for specific clinical indications) and there has also been a significant decrease (25%) in the number of specimens submitted to the laboratory. Further efficiencies may be obtainable with increased automation.