A urine sample provides healthcare providers with a non-invasive way to assess overall health and diagnose various conditions, such as kidney disorders or potential infections. To ensure accurate results, the standard collection method is the “clean-catch” sample. This method is specifically designed to minimize the introduction of outside substances into the specimen cup, which is essential for laboratory analysis to deliver a meaningful result.
External Contamination Sources
The primary reason for performing a cleansing wipe is to remove microorganisms and debris naturally present on the external genital and urethral areas. The skin surrounding the urinary opening harbors commensal bacteria and shed epithelial skin cells. These contaminants can easily be washed into the collection cup during urination.
For female patients, contamination sources also include vaginal discharge or residual fecal matter near the anus. The specialized antiseptic wipes temporarily reduce the concentration of these surface contaminants. Voiding the initial stream of urine into the toilet serves a distinct, mechanical purpose: this initial flow flushes out any bacteria lingering just inside the opening of the urethra, ensuring the mid-stream urine collected is representative of what is in the bladder.
Impact on Diagnostic Accuracy
A contaminated sample can lead to misleading laboratory results, complicating medical decision-making. The presence of external bacteria or skin cells can cause a “false positive” result, suggesting a urinary tract infection (UTI) when no true infection exists. Laboratories interpret bacterial growth above a certain colony-forming unit (CFU) threshold as a true infection.
If the sample is contaminated, the high bacterial count from the skin can cross this threshold, leading to an incorrect UTI diagnosis. This error necessitates re-testing, which delays diagnosis and treatment. Furthermore, a false positive may result in the unnecessary prescription of antibiotics, contributing to rising healthcare costs and antibiotic resistance. Accurate diagnosis from a clean sample prevents these complications.
Step-by-Step Collection Procedure
The clean-catch method requires adherence to specific steps to ensure an uncontaminated specimen is obtained. First, thoroughly wash your hands before handling the collection cup or antiseptic towelettes. Open the sterile collection cup, placing the cap upside down on a clean surface without touching the inner rim or inside of the container.
For female patients, sit on the toilet and use one hand to spread the labia apart, holding them open throughout the collection. Use the provided antiseptic wipe to clean the area from front to back using a single, smooth motion, and then discard the wipe. For male patients, if uncircumcised, pull back the foreskin completely before using a wipe to clean the head of the penis.
Begin urinating a small amount into the toilet to flush the urethral opening of contaminants. Without stopping the flow, move the collection cup into the urine stream and collect the “midstream” portion until the cup is about half full. Finish urinating the remaining urine into the toilet, then securely fasten the cap onto the cup without touching the inside. The cup should be delivered to the healthcare provider or laboratory as soon as possible, or stored according to instructions.