What indicates vaginal or urethral contamination of urine samples?

The presence of greater than 10 squamous epithelial cells per high power field in a urine sample indicates possible contamination from the vaginal or urethral area. Squamous epithelial cells originate from the lining of the urethra or vagina, and their elevated presence suggests that the urine sample may not have been collected in a sterile manner or may have been contaminated by external genital flora.

In clinical practice, interpreting urine samples requires careful consideration of cellular components. A significant number of squamous epithelial cells can undermine the reliability of the urine culture, as it points to the likelihood that the sample was influenced by external bacteria or debris rather than solely reflecting the status of the urinary system. Thus, when evaluating urine for diagnostic purposes, a high count of these cells is a clear indicator that contamination has occurred.

The presence of leukocytes and bacteria can indicate infection or inflammation within the urinary tract, while lower specific gravity does not provide direct evidence of contamination but rather reflects the concentration of solutes in urine. Consequently, they do not serve as specific indicators of sample contamination like squamous epithelial cells do.