The most desperate patient may perform the following:
1. The patient should abstain from illegal drug use for as many days as possible before the test. Within 24 hours of the test, the user should drink considerable quantities of water.
2. Just prior to the test, the user must void the bladder completely.
3. A fresh urine sample must be obtained from a donor, whose urine has the proper constituents or contains no illicit drugs.
4. A Foley catheter is then passed through the user's urethra and into the bladder.
5. The donor's urine is passed through the catheter and into the user's bladder.
6. Then the user must have the drug screen performed as soon as possible to prevent any drugs or metabolites from being processed by the kidneys and secreted into the donor urine.
7. The urine from the donor should match the sex of the patient. Estrogen levels appropriate for a woman would look mighty strange in a man's urine (although drug tests don't normally check for such things.
This is the most desperate attempt a patient may take in order to pass an observed drug screen. If a patient is suspected of tampering with his or her urine an observed drug screen should be performed. If that same patient is suspected of further tampering then the only way to ensure that a proper urine specimen is obtained is to have the patient urinate completely under observation, then have the patient drink copious amounts of water and wait at least 1 hour before collecting another observed specimen. This ensures that the urine contained in their bladder has actually come from the patient and not a donor patient. This is one of two ways to be 100 percent sure that a patient’s urine drug screen is accurate, even under observation. The other way is to collect a blood specimen for analysis.