The “clean catch” method is a specific procedure for collecting a urine sample, designed to prevent contamination from bacteria or cells that naturally reside on the skin around the urethral opening. Contamination can lead to inaccurate laboratory results, especially when a culture is performed to check for a urinary tract infection.
By carefully following the clean catch steps, the specimen collected more accurately reflects the composition of the urine inside the bladder. This technique is essential for proper diagnosis and treatment planning, as it confirms that any detected microbes truly originate from the urinary system.
Preparing for the Clean Catch
Before beginning the physical cleansing process, gathering the necessary supplies is important to maintain sterility and ensure a smooth collection. You will typically be provided with a sterile collection cup and antiseptic towelettes, though mild soap and water can sometimes be used as an alternative. The first action must be a thorough handwashing with soap and warm water, scrubbing for at least twenty seconds. This step removes transient bacteria from the hands and prevents introducing external contaminants to the cup or the genital area.
Next, open the sterile collection cup, taking extreme care to avoid touching the inner surface or the rim, which would compromise its sterility. Place the lid face-up on a clean surface or invert it so the inner surface does not touch anything.
Step-by-Step Cleansing Instructions
The physical cleaning of the urethral area is a specific process necessary to remove surface bacteria.
For female patients, the labia, or skin folds around the urinary opening, must be separated and held apart throughout the entire cleaning and collection process. Use the provided towelettes to wipe the area from front to back. Ensure that each wipe is used only once to avoid spreading bacteria from the anal region forward. This front-to-back motion physically removes contaminants away from the urethra.
Male patients who are uncircumcised must first fully retract the foreskin to expose the head of the penis and the urethral opening. The antiseptic wipe is then used to clean the tip of the penis in a circular motion, or with a single wipe across the opening. This action targets the skin where bacteria most commonly colonize before the urine flow begins. It is important to discard the used wipe immediately without letting it contact the cleaned area again.
The Midstream Collection Method
Once cleansing is complete, the collection requires the “midstream” technique to acquire the least contaminated sample possible. The initial flow of urine is intentionally directed into the toilet for a few seconds. This beginning stream serves the purpose of flushing out any remaining microorganisms or cells that may have lingered in the first part of the urethra.
After this initial flush, the urine flow should be stopped briefly. The sterile collection cup is then introduced into the path of the stream. The patient should begin urinating again, allowing the middle portion of the urine—the “midstream”—to flow directly into the cup.
The cup should be filled to the required level, typically half-full, without letting the cup touch the surrounding skin. Once the adequate volume has been collected, remove the cup from the stream, and pass the remaining urine into the toilet.
Post-Collection Handling
Immediately after the collection cup is removed from the urine stream, it must be sealed tightly to prevent leakage and further contamination. Screw the lid on securely, taking care not to touch the inside of the lid or the cup’s rim. Maintaining this sealed environment is crucial for specimen integrity.
The container must then be clearly labeled with the required patient information, including the full name, date of birth, and the time the sample was collected. This labeling ensures the specimen is correctly identified upon arrival at the laboratory. To maintain sample integrity, the urine should be delivered to the lab as quickly as possible, ideally within one hour of collection. If a delay is unavoidable, the sample should be refrigerated at approximately 4 degrees Celsius for no longer than 24 hours, as cooling slows the multiplication of any bacteria present, thereby preventing inaccurate test results.