Urinalysis Collection and Results in Pelvic Organ Prolapse
Urinalysis Collection and Results in Pelvic Organ Prolapse
These data suggest that the method of urine collection affects urinalysis results in women with advanced urogenital prolapse. There was inadequate agreement between collection techniques on all major components of a microscopic UA with the exception of nitrites. Urine collected via the MSCC technique had significantly higher levels of leukocyte esterase, squamous epithelial cells, and WBC compared to catheterized specimens.
Previous studies demonstrate the clinical equivalence of the MSCC technique to catheterization in women undergoing urinalysis (Chen, Parviainen, & Jeyabalan 2008; Guss et al., 1985; Knopp & Walter, 1989). MSCC and catheterized specimens were compared in a study on pregnant women being evaluated for preeclampsia (Chen et al., 2008). In this study, the investigators identified a significant correlation with a correlation coefficient of 0.897 (p < 0.001) between specimens and concluded that routine catheterization was not necessary in these women. Our study differs from the prior literature in that our patient population has advanced urogenital prolapse extending to or beyond the vaginal hymen. There are minimal data on the manner in which urogenital prolapse affects the accuracy of urine collection techniques. Our findings support the hypothesis that the MSCC technique does not yield accurate UA results in women with advanced urogenital prolapse.
A potential limitation of this study is the sample size. Sample size and power calculations for the kappa statistic in a k x k table (where k > 2) are complex and not readily accessible via available statistical software. The calculation is further complicated in the case of weighted kappa, which was the planned method in this study. A sample size of 72 was calculated as the sample size required for the valid application of weighted kappa based on the formula derived from Cicchetti and Fleiss (1977).
Another limitation of our study is the possibility of measurement bias. Although participants were given standard instructions for the MSCC technique, it is possible that the collection may have been performed more carefully in the context of a clinical trial compared to usual routine care. However, if this occurred, we would expect more agreement between techniques because patients would be wiping more carefully, leading to less contamination. Despite the potential for more careful cleansing in the setting of a clinical trial, there was insignificant agreement between techniques for all major components of the UA besides nitrites. In our study, urine cultures were performed on the catheterized specimens only. This was due to elevated costs and our hypothesis that MSCC urine specimens were not accurate in women with ad vanced prolapse. We hypothesized that the MSCC technique would yield inaccurate UA results in women with advanced urogenital prolapse due to contamination of the specimen by the prolapsed tissue. When urogenital prolapse extends to or beyond the hymen, we believe there is a high likelihood that urine runs over the prolapsed vaginal tissue as it exits the urethra. This would lead to contamination of a clean catch urine specimen. In addition, advanced urogenital prolapse has been shown to induce bladder outlet obstruction secondary to mech anical urethral kinking or compression by the prolapse (Rich ardson, Bent, & Ostergard, 1983; Romanzi, Chaikin, & Blaivas, 1999). This compression can potentially alter the urinary stream making a clean catch specimen more difficult to obtain.
Discussion
These data suggest that the method of urine collection affects urinalysis results in women with advanced urogenital prolapse. There was inadequate agreement between collection techniques on all major components of a microscopic UA with the exception of nitrites. Urine collected via the MSCC technique had significantly higher levels of leukocyte esterase, squamous epithelial cells, and WBC compared to catheterized specimens.
Previous studies demonstrate the clinical equivalence of the MSCC technique to catheterization in women undergoing urinalysis (Chen, Parviainen, & Jeyabalan 2008; Guss et al., 1985; Knopp & Walter, 1989). MSCC and catheterized specimens were compared in a study on pregnant women being evaluated for preeclampsia (Chen et al., 2008). In this study, the investigators identified a significant correlation with a correlation coefficient of 0.897 (p < 0.001) between specimens and concluded that routine catheterization was not necessary in these women. Our study differs from the prior literature in that our patient population has advanced urogenital prolapse extending to or beyond the vaginal hymen. There are minimal data on the manner in which urogenital prolapse affects the accuracy of urine collection techniques. Our findings support the hypothesis that the MSCC technique does not yield accurate UA results in women with advanced urogenital prolapse.
A potential limitation of this study is the sample size. Sample size and power calculations for the kappa statistic in a k x k table (where k > 2) are complex and not readily accessible via available statistical software. The calculation is further complicated in the case of weighted kappa, which was the planned method in this study. A sample size of 72 was calculated as the sample size required for the valid application of weighted kappa based on the formula derived from Cicchetti and Fleiss (1977).
Another limitation of our study is the possibility of measurement bias. Although participants were given standard instructions for the MSCC technique, it is possible that the collection may have been performed more carefully in the context of a clinical trial compared to usual routine care. However, if this occurred, we would expect more agreement between techniques because patients would be wiping more carefully, leading to less contamination. Despite the potential for more careful cleansing in the setting of a clinical trial, there was insignificant agreement between techniques for all major components of the UA besides nitrites. In our study, urine cultures were performed on the catheterized specimens only. This was due to elevated costs and our hypothesis that MSCC urine specimens were not accurate in women with ad vanced prolapse. We hypothesized that the MSCC technique would yield inaccurate UA results in women with advanced urogenital prolapse due to contamination of the specimen by the prolapsed tissue. When urogenital prolapse extends to or beyond the hymen, we believe there is a high likelihood that urine runs over the prolapsed vaginal tissue as it exits the urethra. This would lead to contamination of a clean catch urine specimen. In addition, advanced urogenital prolapse has been shown to induce bladder outlet obstruction secondary to mech anical urethral kinking or compression by the prolapse (Rich ardson, Bent, & Ostergard, 1983; Romanzi, Chaikin, & Blaivas, 1999). This compression can potentially alter the urinary stream making a clean catch specimen more difficult to obtain.
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