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Urine drug screen

Definition

A urine drug screen is used to detect illegal and some prescription drugs in the urine.

Alternative Names

Drug screen - urine

How the test is performed

Before the test, you may be asked to remove all your clothing and wear a hospital gown. You will then be placed in a room where you have no access to your personal items or water. In this environment, you cannot dilute the sample, nor can you use someone else's urine for the test.

This test involves collecting a "clean-catch" (midstream) urine sample:

  • Wash your hands with soap and water. Dry your hands with a clean towel.
  • Men and boys should wipe clean the head of the penis with a moist cloth or disposable towlette. Before cleaning, gently pull back (retract) the foreskin, if you have one.
  • Women and girls need to wash the area between the lips of the vagina with soapy water and rinse well. Or if instructed, use a disposable towlette to wipe the genital area.
  • As you start to urinate, allow a small amount to fall into the toilet bowl. This clears the urethra of contaminants.
  • Then, in the container you are given, catch about 1 - 2 ounces of urine. Remove the container from the urine stream.
  • Give the container to the health care provider or assistant.
  • Wash your hands again with soap and water.

The sample is then taken to the laboratory for evaluation.

How the test will feel

The test involves only normal urination.

Why the test is performed

The test is performed to detect the presence of illegal and some prescription drugs in your urine. Their presence indicates that you recently used such drugs.

Normal Values

No drugs in the urine.

What abnormal results mean

If the test result is positive, another test called gas-chromatography mass spectrometry (GC-MS) may be done to confirm the results. The GC-MS will help tell the difference between a false positive and a true positive.

In some cases, a test will register a false positive. This can result from interfering factors such as some foods, prescription medications, and other drugs.

References

Pincus MR, Abraham NZ Jr. Toxicology and therapeutic drug monitoring. In: McPherson RA, Pincus MR, eds. . 22nd ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 23.

Encyclopedia content is provided as information only and not intended to replace the advice and instruction from your personal physician.