Further testing in the laboratory involves culturing the bacteria from the urine (by growing it in a special medium) and testing different antibiotics on it to see which one is most effective.
How your urine sample is handled in hospital may be different. Larger hospitals have a laboratory on site and patients will usually wait in the emergency department for the results of the laboratory microscopic evaluation. Doctors then start treatment with this extra information.
Patients sent home from the emergency department will still need to visit their GP for the final laboratory results, such as the antibiotic sensitivities. If you are admitted to hospital, treatment will start and may be modified once these results are known.
Sterile samples are vital
For any of these tests to be valid, the urine sample needs to be sterile (without contamination). To obtain a sterile sample in hospital, that might involve inserting a catheter (a tube that collects urine from the bladder) or a needle into the bladder (suprapubic aspiration).
But the most common method is by asking for a mid-stream urine sample (also known as clean-catch urine sample). This is when you urinate the first part of the urine stream into the toilet, collect the middle part of the stream in a sterile container, then empty the rest of the bladder into the toilet.
The idea is that the first discarded urine flushes out any bacteria or skin cells from the penis or vagina leaving the mid-stream sample as a truly representative sample to test.
Instructions are often vague
But many patients will recall being asked to provide a urine sample without adequate explanation of how to do it. They are simply handed a sample container and given directions to the toilet.
Without instruction patients may not know how to prepare their external genitalia. For women this involves parting the labia or lips of the vagina, while for men, this involves retracting the foreskin.
Nor are patients clearly advised how to provide the sample. As a result, they can contaminate the container and its lid by not washing their hands, and their sample often contains the first rather than mid-stream urine.
In these cases, what actually gets into the sample are contaminants; cells and bacteria from hands; or cells and bacteria from the lower part of the urinary tract and genitalia.
Unfortunately for women, their anatomy is more likely to result in more of this latter contamination. They void urine from the urethra (the tube from the bladder) and through a part of the vagina, while men most often void directly into the container.
Why is a contaminant-free sample important?
If the sample is contaminated there are various consequences. The laboratory will report contamination and advise the doctor to take care in interpreting results. However, a contaminated sample can result in incorrect diagnosis and incorrect or unnecessary treatment.
A new sample will probably be needed. This causes delays in diagnosis and treatment, potential anxiety to the patient and additional costs.