Correlation of catheterized and clean catch urine protein/creatinine ratios in preeclampsia evaluation

To examine whether clean catch urine specimens correlate with catheterized specimens for determination of protein/creatinine ratios in pregnant women being evaluated for preeclampsia.

Sixty pregnant women who were at least at 20 weeks of gestation were enrolled. Patients with ruptured membranes, vaginal bleeding, or urinary tract infections were excluded. Midstream clean catch urine specimens were collected. Catheterized specimens were then collected and used for clinical management. The specimens were analyzed for protein, creatinine, urinalysis, and culture. Based on sample size calculations, 60 participants were needed to detect a correlation of 0.90 with 80% power and alpha=0.05.

Mean gestational age at enrollment was 35.9 weeks (range 23.1-41.7 weeks). Median (range) clean catch and catheterized protein/creatinine ratios were 0.204 (0.089-3.465) and 0.181 (0.067-3.335), respectively, with a correlation coefficient of 0.897 (P<.001). When results were categorized by degree of proteinuria using a cutoff of 0.3, sensitivity and specificity of the clean catch protein/creatinine ratios were 95.2% and 97.4%. When using a more conservative cutoff of 0.19, sensitivity and specificity of the clean catch protein/creatinine ratios were 96.4% and 75.0%.

Clean catch and catheterized urine specimens correlate well in women with suspected preeclampsia. Routine catheterization of pregnant women is not necessary in the evaluation of preeclampsia.