- Transfusion requests
- Sample timing
- Cross matching
- Key factors known to affect test performance or interpretation
The transfusion laboratories at Friarage and James Cook aim to issue blood components for transfusion to the right place and on time. For this to be achieved we must have full, accurate and legible information on the request form and specimen.
Please note the following important points:
- All specimens for blood grouping and antibody screens and requests for blood transfusion should be supplied in a 6 ml EDTA, (pink top) vacutainer tube.
- All transfusion samples MUST be labelled by hand, at the patient’s side, by the person who has taken the sample. Please ensure that all specimens are labelled with the following three points of identification:
- Full name (the patient’s surname and first name)
- Date of birth
- Hospital number
- If a hospital number is available for the patient it MUST be used at all times. The hospital number will be a 6 digit number prefixed with the letter J, F or D. Please provide this on the request form and hand write the hospital number on the specimen. The hospital number is important as it will help the laboratory identify any previous transfusion records for the patient. Duplicate patient records must be avoided on the transfusion laboratory computer system otherwise essential transfusion requirements for the patient may be overlooked.
- If a hospital number is not available the NHS number may be used.
- If no hospital number or NHS number are available an emergency number issued through A&E is an acceptable alternative.
- Addressograph labels must not be used on transfusion samples. If using pre-printed addressograph labels on request forms please ensure that the details are correct for that particular episode, e.g. the patient’s surname, address, consultant or hospital may have changed since the labels were printed.
- Please provide information on the request form relating to:
- The reason for the request
- Where the transfusion or operation is to take place
- The date and time the transfusion or operation is scheduled
- The type of blood component and number of units required including any special requirements
- Whether the patient has a history of transfusion or known antibodies
- The clinical details section for ante-natal requests
- The name of the patient’s hospital consultant in case there are any queries concerning the request
- The laboratory will reject inadequately labelled specimens and specimens where there are discrepancies between the information provided on the sample and request form.
- The sample and form must be signed by the person taking the blood. Individuals taking samples for transfusion should be aware of the competencies for taking venous samples for transfusion outlined in the NPSA Safer Practice notice 14 ‘Right Patient, Right Blood’. It is the responsibility of the PCT or hospital to ensure that staff taking samples for transfusion purposes are appropriately trained. If further advice or assistance with training is required please contact the transfusion practitioners at James Cook extension 52802. Direct line 01642 282802.
Group and save samples for serological cross-match are routinely stored for seven days.
- If a patient has not received a transfusion, is not pregnant or has not been pregnant in the last three months; the sample is valid for seven days.
It is essential that clarification is made with the patient that they have not received any blood transfusion treatment at any other hospital within a three month period.
A fresh blood sample is required to screen for antibodies if the patient has had a transfusion more than three days previously.
- If a patient has had a transfusion or is/has been pregnant in the last three months, the sample must be less than three days old at the beginning of the transfusion.
- Long term chronically transfused patients with no alloantibodies may not need a sample taken within the three day rule if a valid clinical risk assessment is present, allowing samples to remain acceptable for up to sveven days.
- Pregnant women who have not been transfused in the last three months but require blood to be reserved on stand-by e.g. for placenta praevia, a sample must be tested within seven days.
|Patient transfused within:||Sample requirements:|
|0-3 days||New sample may not be required. Please check with transfusion laboratory extension 52630|
|3 days to 3 months||Sample valid if taken not more than three days* before transfusion|
|Greater than 3 months||Sample valid if taken not more than seven days before transfusion|
*This is the time between the sample being taken and the subsequent transfusion.
The 3 days includes the time that the blood is reserved for the patient, e.g. if the sample was 1-day old, the blood would have to be transfused within 2 days.
Day of surgery admission patients: See DOSA blood transfusion pathway for full details.
If the patient is suitable for electronic issue* and a pre-op assessment sample is covering the operation, then it is essential that a pre-transfusion sample is obtained prior to transfusion of the first unit of blood.
- Where the pre-transfusion sample is taken on the day of surgery, there is no requirement to wait for the results before starting the procedure.
- The pre-transfusion sample can be a sample taken within the previous seven days as long as the patient has not been transfused or pregnant in the last three months.
Electronic issue (EI) is the selection and issue of red cell units where compatibility is determined by the Laboratory Information Management System (LIMS) without serological testing (serological crossmatch) of donor cells against patient plasma.
The ability to perform EI depends on robust IT rules and laboratory processes and on patient transfusion history and sample criteria as specified in national guidelines (BCSH IT and BCSH Guidelines for pre-transfusion compatibility procedures in blood transfusion laboratories).
Laboratory staff will advise on whether urgent requests for blood can be made available rapidly by EI based on the following criteria:
If ALL of the following patient and sample criteria are met, then electronic issue is acceptable for that patient sample:
- Blood group interpretation on the current sample is identical to the historical record.
- No manual amendments have been made to automated results.
- The current antibody screen is negative.
- The patient’s group and antibody screen results are complete and fully authorised in the LIMS.
- The patient does not have a previously known antibody of likely clinical significance.
- Patient is not excluded on clinical grounds
- The patient must not have a positive DAT
- A solid organ transplant (three month exclusion)
- An allogeneic bone marrow transplant (one year exclusion)
- The current sample meets the sample timing and storage requirements detailed above.
A serological crossmatch is required if the antibody screen is positive or if the patient’s plasma contains or has been known to contain, red cell alloantibodies of likely clinical significance.
Patients must be over four months old to be eligible for electronic issue (EI).
For routine cross-matching, specimens need to reach the laboratory BEFORE 4pm on a weekday for blood required next morning or 11am on a Sunday for blood required Monday morning. Routine crossmatch requests on patients with a current Group and Save specimen already in the laboratory will be accepted up to 4pm on a weekday for blood required next morning.
Emergency crossmatched blood can usually be supplied within 45 minutes.
All requests for blood required in less than four hours must be telephoned to the laboratory.
Key factors known to affect test performance or interpretation
- Samples will be rejected if received more than 48 hours post phlebotomy.
- It is not possible to provide accurate blood grouping on clotted samples or haemolysed samples, including those stored at inappropriate temperatures.
- Small samples must be processed manually and these will only be accepted for young children.
- All patients requiring a group and save are tested for red cell antigens and antibodies in the plasma. In some patients antibodies may not be detectable – this includes neonates, very elderly patients and those with immunodeficiency – in these patients the red cell antigens are checked twice as a confirmatory test. Blood groups may also be affected by recent medical interventions, particularly bone marrow transplantation, and it is important to inform the laboratory about this.