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Dr. D. Love
Dr. D. Love, Doctor
Category: Medical
Satisfied Customers: 18767
Experience:  Family Physician for 10 years; Hospital Medical Director for 10 years.
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What is "first Void urine"? I took a std test and on the

Customer Question

What is "first Void urine"? I took a std test and on the results it said only accurate with a first void urine sample. I called them and they told me that it means an "unclean" urine sample. But I asked some other people and they say it means the first pee of the day
Submitted: 6 years ago.
Category: Medical
Expert:  Dr. D. Love replied 6 years ago.

A first void urine sample is the first urine that is passed (voided) in the day (or upon arising if on an altered sleep schedule). The first voided urine is typically the most concentrated, since there has been no oral intake of fluids during the night. As the day progresses and there is intake of fluids, the urine becomes less concentrated. Since many urine tests are looking for a certain concentration of a substance, the most concentrated urine would be the most sensitive. For these tests, if the urine is collected later in the day, the results are still fairly accurate and are reliable if positive, but would have a higher incidence of false negatives.

Customer: replied 6 years ago.
Is a the first urine of the day needed for chlamydia test? I gave them my 2nd urine of the day with no food and only a few cups of water before I gave the sample
Expert:  Dr. D. Love replied 6 years ago.

Since the report said that it was to be done on a first voided urine sample, that would be preferred. However, the second urine of the day with only a small amount of water would still be quite accurate.

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Expert:  Dr. D. Love replied 6 years ago.

I have done some research looking for the sensitivity of urine later in the day, and the tests would still be very accurate if done later in the day on the first portion of the urine that is passed, as long as it has been at least an hour since last urination. Therefore, some tests will also use the term of first void to refer to this initial portion of a sample collected at least an hour since last urination.