Urines Flashcards
(44 cards)
What tests are done on urine samples
Sedimax analysis for wcc, rcc, epi count
HCG/Pregnancy Test
Listeria rapid antigen test
How does the SediMax work
On board the analyser, urine is mixed until homogenised
0.2ml of the sample is taken up and transferred ino a special disposable cuvette by a pipette
The pipette is then rinsed with instrument feed water (IFW) to avoid cross-contamination
Cuvettes containing sample are then centrifuged at 2000 RPM for 10 seconds which forces all the particles in the urine to sediment onto a single plane on the bottom of the cuvette, this is where the camera focuses on
The built-in camera then takes both bright-field and phase-contrast pictures through a microscope at 10 different points across the specimen
A high-performance image evaluation software then processes all of the images to detect and classify and particles
All the images are then stored on the analysers memory which can hod 10000 records
What is the principle behind the SediMax
A fully automated urine analyser
Uses bright-field and phase-contrast microscopy to visualise and recognise formed elements of urine
What cells can the SediMax identify?
Red Blood Cells (RBC);
White Blood Cells (WBC);
White Blood Cell clumps (WBCc);
Hyaline Casts (HYA);
Pathological Casts (PAT);
Squamous Epithelial Cells (EPI);
Non-Squamous Epithelial Cells (NEC);
Bacteria (BAC); Bacteria Rods(BACr);
Bacteria Cocci(BACc)
Yeast (YEA);
Crystals (CRY):
Calcium-oxalate monohydrate (CaOxm),
Calcium-oxalate dihydrate (CaOxd),
Uric acid (URI),
Triple phosphate (TRI);
Mucus (MUC),
Sperm (SPRM),
Amorphous material (AMO)
How is the SediMax maintained?
Run Milton disinfectant once every day first thing in the morning
QC ran twice a day, once in morning, once in afternoon -> Two controls, a high and a low control
What urines are cultured
Any urines with a white cell count greater than 20
Urines are also cultured upon request or if the patient is immunocompromised i.e. from St. Vincent’s ward etc
What will you have to do if the white cell count is very high on a urine sample?
If WCC is very high you will have to dilute the sample 1 in 10 in saline
You then run the sample as normal but change the dilution factor so that the correct result goes across
If wcc still too high then repeat the dilution to create a 1 in 100 dilution
What is the name of the tubes used on the SediMax?
Sedivette tubes
How much urine is needed for analysis of urine?
At least 2 mls -> if less urine then this than a manual will have to be done using a cell counter
How many pictures does the SediMax take of a sample?
SediMax will take 10 pictures of different areas on the sample
If wccs too high in a certain picture the SediMax will not count this: 9/10 pictures taken
7/10 pictures or less will have to be diluted
Do you culture a urine if the bacterial count or rcc is high?
No -> only if wccs also high
What would a high urine bacteria count without a raised white cell count mean?
Poorly taken sample
Urine is meant to be a midstream urine
Bacteria without wcc = commensal bacteria
Patient could also be immunocompromised
What would a raised red cell count without wcc mean?
Patient could be menstruating
It would be up to the consultant to determine the cause of the raised rbcs, the urine can be cultured if requested
When would you carry out a manual urine
Only done when there is very little sample i.e. less than 2mls
How would you carry out a manual urine?
Carried out using a cell counter
Cell counter composed of six squares broken down into 16 squares
Manually count the ebcs, rbcs and epis in one of the sets of 16 squares
If too many cells in sample you can carry out a dilution just make sure to multiply results up to account for the dilution factor
How did you deal with casts and crystals in urine
There is no quantitative measurement of either
They are detected through microscopy
Detection is qualitative
Detection is not diagnostic, only really informs the consultant on the patient’s diet
Talk about the HCG pregnancy test
One of our urgent tests as the patient is usually due to go for surgery
A negative pregnancy test is required prior to surgery for females
It’s a simple antigen test which only takes 3 minutes
If there is any feint line showing any positivity then a second test should be carried out
If still unsure then ask another scientist
Talk about the legionella or pneumococcal antigen tests
Specific antigen tests done upon request
Pneumococcal antigen test usually done if query pneumoniae -> detects S. pneumo in urine
Legionella antigen test only done for patients in A&E or HDU/CHDU but can be added on by the consultants if required
What agar are positive urines put up on?
Chromagar Orientation Plates
What is the Chromagar Orientation plate?
a non-selective chromogenic culture medium intended for use in the qualitative direct detection, differentiation and presumptive identification of uropathogens to aid in the diagnosis of urine tract infection
What are the most common urinary pathogens?
E. Coli (majority)
Enterobacter (Ents)
Staphylococcus Saprophyticus in young women
What colour will an E. Coli grow on urine chromagar?
E. Coli = pink
What colour will GNBs grow on brilliance chromagar
GNBS = large and blue but some can also be colourless
What colour will your Ents grow on Brilliance chromagar
Ents = bright blue (smaller than GNBS and not as dark)
