MSU (Mid Stream Urine sample) How to

When you visit the surgery we often ask for a sample of urine, its known as a Mid Stream Urine sample or MSU.

The aim is to obtain a sample (specimen) of urine from the middle of your bladder. Urine does not normally have any germy (bacteria) in it (urine should be sterile). If bacteria are found in the sample, it means that the urine is infected. A midstream sample is best, as the first bit of urine that you pass may be contaminated with bacteria from the skin.


How to take an MSU sample:


Before doing an MSU, wash your hands and ideally your genitals as well.

Women – hold open the entrance to the vagina (your labia)

Men – pull back your foreskin

Pass some urine into the toilet

Then, without stopping the flow of urine, catch some urine in a clean (sterile) bottle. (The bottle is usually provided by a doctor or nurse) Once you have enough urine in the bottle, finish off passing the rest of your urine into the toilet.

Do not open the sterile bottle until you are ready to take the sample. Avoid touching any part of your genitals with the bottle, as this will increase the risk of contamination. Put the cap back on the container.

You need to fill the bottle to the top of the label. Some specimen bottles contain a powder which helps the sample last longer for testing (a preservative). If this is the case, a mark on the bottle will indicate the ideal amount of urine.

However, if that is difficult, any amount is better than none. The sooner the sample is given in to the doctor’s surgery, or to laboratory, the better. Within two hours is best, if that is not possible, put the sample in the fridge until you take it to the doctor or laboratory.

If it is difficult to aim your urine stream into the bottle, you may use another container such as a jam jar or a disposable plastic cup. You can then pour the urine into the sterile bottle. If you do this, make sure the container you pass water into is as clean as possible. Wash it well and rinse it with boiling water. You should still pass the first part of your urine stream into the toilet. In this way, you are collecting the urine from the bladder.

The result of an MSU takes 3-7 days to be reported by the lab.

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