Tag Archives: urine

“Hidden Agendas”


In my pursuit of clinical details for all request forms, I have been asked a few times specifically about urine samples. Why bother adding clinical details for a urine sample that is sent to the lab. Is the request not obvious?

However when you think about it and examine a little more closely there are actually many “less obvious” reasons that a urine sample is sent to the lab. Take the following examples below:

Test of Cure: Once symptoms have settled, this is generally not indicated.

As part of an admission screen: Positive predictive value, even in an elderly patient, must be awful.

Prior to orthopaedic (or other) surgery: With the exception of urological surgery, the evidence is now strongly against this.

Wellness check: Just in case…even if you did culture bacteria, treatment would not be indicated in an asymptomatic patient.

Insurance/Immigration requests: as above.

Looking for proteinuria or glucose: In diabetics. Requestor not interested in culture result.

Looking for haematuria: If lab not aware, likely to increase risk of false negative due to sub-optimal testing.

Cloudy/smelly urine in catheter bag: Sending such a sample to the lab is hardly ever indicated.


So as you can see there are actually many reasons that urine samples sent to the lab. There are probably many more which I have not thought of from the top of my head. Many are inappropriate, others are nothing whatsoever to do with infection.

With regards to patients with “symptoms”, there can be a whole range of clinical scenarios, from acute dysuria and frequency to non-specific fatigue. Each set of symptoms will have a different pre-test probability and will therefore potentially affect how the test is reported and interpreted, particularly for borderline results.

And then there all the supporting clinical details which may affect how the test is processed and reported, e.g. pregnancy, immunocompromise, antibiotic allergies, presence of catheter, presence of urinary stents etc etc..

So if someone says to you there is no point in submitting clinical details for urine specimens, I would strongly object to this for all of the reasons above.

In short there is no excuse for not submitting clinical details, not for urine samples or any other samples. Don’t let anyone tell you otherwise….



Back to Basics

Working on the urine bench always brings to the front of my mind the lack of understanding that some clinical staff have of the basics of microbiology and the commonly used abbreviations – Note that I said some and not all.

We frequently see request forms with statements such as “MSU Bag urine” – which one is it? A MSU or a Paediatric Bag collect? or “MSU” but with clinical details that the patient has a “permanent SPC” – again is it an MSU or a Catheter specimen? or most commonly “MSU” written under tests required which in my opinion is being mixed up with the abbreviation MC&S (short for microscopy, culture and sensitivities). MSU is not a test but a specimen type. It is an abbreviation of Midstream Urine as opposed to other urine types such as CSU or Catheter spec urine, EMU or early morning urine, Aspirated urine or just a random collect or clean catch collect.

This may seem to be a bit pedantic but the type of specimen we receive in the laboratory has a bearing on what and how we report out to the clinician and whether or not we deem it relevant to report sensitivities. For example, a true MSU should have less chance of having cellular and/or bacterial contamination as opposed to a clean catch urine which often has larger numbers of epithelial cells present and often vaginal contamination if collected from female patients. Also, growth from a catheter specimen is less likely to get sensitivities reported due to the fact that the presence of bacteria and/or cells is often reflective of colonisation rather than infection and changing the catheter, if in situ for a longer term, will often be more effective than antibiotic treatment. Again this is where it is important for the laboratory to be given relevant clinical details so we know if the patient is showing signs of systemic involvement in which case antibiotics will be reported, or if the catheter is merely an in/out catheter for collection purposes as opposed to a long-term solution for a tetraplegic.

It is also important that the correct urine type be collected for the right purpose. If a clinician is wanting testing for TB then an MSU is not going to be sufficient and will be rejected by the laboratory. They will need to ensure a full early morning collect is sent through to the lab so that it can be further concentrated to optimise the chances of isolating any Mycobacteria present. Likewise, random urine collects, although adequate for screening purposes is not the preferred specimen for accurate biochemical dipstick testing or bacterial isolation due to the fact that the potential exists for dilution if the patient has recently consumed fluids.

All this information assists us as laboratory workers to perform our job to the best of our ability and to put out results that are relevant to patient treatment so it is important for clinical staff to understand the differences and to ask themselves what they are wanting to achieve from their request from the laboratory and then together we can maximise the outcomes for patients.