Occasionally we receive samples that unfortunately cannot be used for testing for a variety of different reasons. Getting a repeat sample is inconvenient for both the owner and practice as well as the potentially stressful to the animal.
To try and reduce the risk of this situation occurring, we have listed below some suggestions for the top 4 sample issues we encounter.
- Book plenty of time to take the sample and make use of topical anaesthetic creams for more anxious/needle-shy patients.
- Only occlude the vein for the minimum time possible.
- Do not use excessive alcohol to swab the site and ensure it is dry prior to sampling; if aspirated alcohol can damage cells within the blood.
- Use a 21-gauge needle in dogs and 23-gauge needle in cats if possible.
- Avoid excessive suction when collecting blood and try a different site if a haematoma forms rather than try to sample through it.
- After sampling, remove the needle from the syringe entirely before slowly decanting the blood into the tubes.
- Do not shake the sample.
- Spin down and separate the serum as soon as possible after sampling balancing the centrifuge before use.
- Always send serum rather than whole blood where possible (whole blood can be sent but a greater volume is required and it is much more likely to haemolyse).
- Post the sample ASAP; store in a fridge until you are able to do so, but avoid posting on a Friday to minimise extended time in the post where the temperature is not controlled.
- Sending a fasted sample will reduce the risk of lipaemia.
3. Insufficient sample
- Remember the volume stated on the consent form is the minimum required, more is always good!
- Separated serum is always preferable to whole blood to reduce the risk of haemolysis but if you have to send whole blood, it should be double the volume required.
- When using gel tubes for serum, remember to spin it down and that the gel doesn’t count as part of the volume.
- Send sufficient serum for all requested tests and ideally any additional tests you may decide to run depending on the results.
4. Wrong blood collection tubes
- Samples must be submitted in either plain or serum (including gel, bead and serum separator) blood tubes.
Send separated serum samples rather than whole blood whenever possible so you:
- can check you have sufficient serum volume before sending
- can evaluate the sample for haemolysis and lipaemia in the practice
- have the potential to resample straight away if necessary, before discharging the patient