A clean catch urine sample is a standard, non-invasive procedure used to collect a urine specimen for testing, primarily to diagnose urinary tract infections (UTIs) and other medical conditions. The method is designed to prevent bacteria from the skin of the genital area from contaminating the sample, ensuring the accuracy of subsequent laboratory analysis. This guide, based on official medical sources, outlines the purpose, procedure, and key considerations for patients in the UK who may be asked to provide a clean catch sample.
The primary reason for requesting a clean catch urine sample is to test for a urinary tract infection (UTI). Common symptoms of a UTI include pain or burning during urination and a persistent urge to urinate. However, a doctor may also request a urine culture as part of a routine physical examination, even in the absence of overt symptoms. Beyond UTIs, urine cultures can be used to check for other conditions, such as unusual infections of the bladder or kidney, stress incontinence, pH levels in pregnant women, the presence of kidney stones, or the presence of drugs in the system. Patients are advised to ask their doctor during an appointment whether a clean catch sample will be required.
The clean catch method involves a specific, multi-step process to minimise contamination. The procedure typically requires a special kit, which may include a plastic container with a lid, a label for personal details, and an individually wrapped, moist towel or sterile wipes. Some clinics may instruct patients to use soapy water instead of providing a moist towel. It is recommended to collect the sample when urine has been in the bladder for approximately two to three hours. The patient should wash their hands thoroughly with soap and warm water.
For individuals with a vagina, the cleaning process is particularly detailed. The patient should sit on the toilet with their legs spread apart and use two fingers to separate the labia. Using a sterile wipe, they should clean the inner folds of the labia, moving from front to back. A second wipe is used to clean the area over the urethra, just above the vaginal opening. If a patient is menstruating, they should insert a fresh tampon to stop the flow before beginning. The urine collection itself is a midstream collection. The patient should urinate a small amount into the toilet bowl, then stop the flow. They then hold the specimen cup a few inches away from the urethra and urinate until the cup is about half full. They may finish urinating into the toilet bowl. The lid should be screwed securely onto the container, which is then wiped clean.
For individuals with a penis, the instructions are to clean the head of the penis with a sterile wipe. The midstream collection process is the same: urinate a small amount into the toilet, stop the flow, then collect the midstream urine in the specimen cup. For infants, the clean catch kit consists of a plastic bag with a sticky strip that fits over the baby’s genital area, as well as a sterile container. The same cleaning methods apply, and after collection, the urine should be poured from the bag into the sterile container.
If a patient is unable to urinate at the clinic or doctor’s office, they may be given a clean catch kit to take home. After completing the collection at home, the sample should be dropped off at the laboratory as soon as possible. If there will be more than 30 minutes before the sample can be delivered, it should be refrigerated. The lab will culture the sample, which typically takes 24 to 48 hours. The doctor will then notify the patient of the results. A positive test result is indicated by cultures with greater than 100,000 colony-forming units (CFU) of a single bacteria, which usually signifies an infection requiring antibiotic treatment. A negative result, showing no growth, indicates no infection is present. If the test shows growth of several different types of bacteria, it likely means the sample was contaminated during collection, although the clean catch protocol is designed to reduce this chance.