pg. 1 UTI collaborative 2018 IK/JA/SM/AH v3
Taking a urine sample
In this leaflet:
Section 1: Mid-stream urine (MSU)
Section 2: Catheter specimen urine (CSU)
Section 3: Patient instructions
Section 1
What is a MSU: A mid-stream urine sample means you don't collect the first or last part of urine that
comes out. This reduces the risk of the sample being contaminated with bacteria from your hands
or the skin around the urethra, the tube that carries urine out of the body. The aim is to obtain a
sample (specimen) of urine from the middle of your bladder. Urine does not normally have any
germs (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.
The “gold standard” for the diagnosis of urinary tract infection is culture, which requires 18 -24 hours
before a result is available.
What is the purpose of a MSU test?
To confirm the diagnosis of a urine infection. The usual symptoms of a urine infection are pain
when you pass urine and passing urine frequently. However, symptoms are not always typical,
particularly in the elderly, so a urine test may be needed.
To decide the best antibiotic to use. Some germs (bacteria) are resistant to some antibiotics. If
the test shows that bacteria are in the urine then the bacteria are tested against various antibiotics.
This finds which antibiotics will kill the bacteria in the urine.
How do I collect a midstream specimen of urine (MSU)?
Before doing an MSU, wash your hands and ideally your genitals as well.
Do not open the sterile bottle until you are ready to take the sample.
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 should be 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.
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 do not need to fill the bottle to the
top; a small amount will do.
MSU pots
If you only have the yellow top MSU pot without a preservative you only have two hours before
the bacteria in the pot will over grow and not be suitable for testing -The sooner the sample is
given in to the doctor's surgery, or to the laboratory, the better. Within two hours is best. If
possible, collect samples in the morning Mon-Friday so the sample can be taken to the surgery
before 11am. However you can ask your GP practice to provide you with the monovette system
which consists of the yellow pot and the green topped vacutainer which contains the preservative,
put the green topped vacutainer in the port so the urine is transferred to the green bottle for
transfer to the GP surgery.
