Test Repertoire and Turnaround Times

Test Repertoire and Turnaround Times

Group and screen

Emergency cases: the Blood Transfusion Department MUST be informed by telephone – these requests will be given priority.

  • Routine group and screen results will be available within 24 hours.
  • Group and screens for antenatal cases will be available within 72 hours.

General information about Group and Screen

A sample for ‘Group and Screen’ means that the patient is ABO and Rh (D) typed, screened for the presence of clinically significant antibodies and then the sample is stored at 4°C for a maximum of 7 days. During this period the sample can be used for compatibility testing at the request of the medical practitioner providing no transfusions have taken place in the previous 3-month period (for further details on sample viability see Transfusion Guidelines).

Transfusion and pregnancy may cause an immune response and units selected for cross matching or antibody screening must take account of this. In situations in which patients are repeatedly or previously transfused, they should be screened for the development of irregular antibodies at regular intervals. Please contact Blood Bank staff for further advice for these patients.

Crossmatch

Urgent cross match- the Blood Transfusion Department must be informed by phone.

Blood should be available within 45 minutes unless:

  • atypical red cell antibodies are detected
  • special requirements are identified
  • patient has been identified not to have any transfusion history (the 2 sample rule would need to be fulfilled)

Non-urgent cross match- blood will be available for the date and time required if sufficient notice is given. If this is not possible, Blood Bank will inform the ward.

Please note that some patients are serologically complicated and testing or cross-matching may have to be referred to NHS Blood and Transplant in Barnsley. In these cases, a specific turnaround time can range from 3 to 8 hours depending on the complexity of the investigation and additional samples may be requested. If blood is required more urgently, contact the Blood Bank immediately.

General information about crossmatch testing

Patients for cross match, must follow the 2 sample rule. 

Electronic issue of blood – following group and antibody screen (and providing that the rules for electronic issue are satisfied), blood will be issued without the need for compatibility testing (cross matching). In these situations blood is available almost immediately.

Compatibility testing – when electronic issue criteria cannot be satisfied, compatibility testing (cross matching) must be performed in order to provide blood. If no antibodies are identified and there are no special product requirements blood may be available within the hour for urgent requests. If an antibody is identified or the patient requires non random units such as; irradiated or CMV Negative, the timescale for blood availability will be extended. The Blood Bank staff will be available to determine and inform medical staff, in each situation.

Transfusion and pregnancy may cause an immune response and units selected for cross matching or antibody screening must take account of this. In situations in which patients are repeatedly or previously transfused, they should be screened for the development of irregular antibodies at regular intervals. Please contact Blood Bank staff for further advice for these patients.

Please inform the Blood Bank if the need for blood changes, in order that wastage is kept to an absolute minimum.

Non-urgent requests when no problems or special requirements are identified should be available for the time and date stated on the request form. Please allow 4 hours for inpatient cross matches and 24 hours for cold surgery.

Please contact Blood bank for advice regarding sample requirements and collection times if:

  • an antibody has been previously identified
  • the patient has been transfused within the last 3 months

If there is a problem in provision of blood for any reason the Blood Bank will notify the ward or requesting clinician as soon as possible. The blood provided will normally be of the same ABO and Rh (D) type as the patient. Blood of a different type may occasionally be provided in the interests of efficient stock management.

Medical practitioners may telephone the department, or send a completed request form to add requests for blood (or blood products) to an existing group and screen sample. A full audit trail must be provided in either case.

Blood Retention 

Cross-matched blood is held for 24 hours from the time and date stated on the request form and is then returned to stock and may be used for other cases. Should a transfusion regimen take longer than 72 hours, a further sample is required in order to identify those patients who may have been stimulated into producing antibodies. This will then allow further compatible units to be provided safely.

Requests for blood to surgical lists should be requested in good time (a minimum of 24 hours in advance) and during the core working day, if possible.

Direct Antiglobulin Test (DAT)

A direct antiglobulin test (DAT) will be available within 24 hours.

N.B Outside core hours non-urgent tests will be batched to maintain efficient working practices so turn around times may be extended in these cases.

General information on DAT

The DAT is used to detect sensitised red cells (coated with antibody). This indicates that there are circulating antibodies directed against the patient’s red cells. These antibodies can cause a haemolytic anaemia and may indicate auto immune haemolytic anaemia (AIHA) where the patient has autoantibodies. In infants, it can indicate Haemolytic Disease of the Foetus and Newborn (HDFN) where maternal antibody (ies) have crossed the placenta.

A positive DAT post transfusion indicates that the transfused red cells are coated with antibody from the patient and will require further investigation. The DAT is an important test in the investigation of transfusion reactions, HDFN and AIHA. To differentiate the reaction, monospecific AHG reagents are used. These are IgG, IgA, IgM, C3c and C3d. For infants an IgG DAT is performed.

Kleihauer Test

A Kleihauer result will be available within 24 hours if the sample is received between Sunday and Friday. The results from a sample received on a Saturday will not normally be available until Monday afternoon. If the result is required urgently or the 72-hour period will be exceeded, please contact the Blood Bank.

Please note: Prophylactic Anti-D may be issued prior to the Kleihauer test being performed. Correct samples must be received prior to issue and the patient must be contactable and made aware that if FMH result is positive, further anti-D may be required.

What is the purpose of a Kleihauer / FMH test?

The Kleihauer test is a blood test used to measure the amount of fetal haemoglobin transferred from a fetus to a mother’s bloodstream. It is usually performed on RhD Negative mothers. This is to determine the required dose anti-D immunoglobulin to inhibit formation of Rh antibodies in the mother, and prevent Rh disease in future RhD-positive children. It is performed when the gestation period is greater than 20 weeks.

Fetomaternal haemorrhage can occur with:

  • intrauterine death
  • stillbirths
  • abortion (including therapeutic abortion)
  • threatened abortion
  • amniocentesis
  • cordocentesis
  • chorionic villus sampling
  • external cephalic version
  • abdominal trauma
  • antepartum haemorrhage
  • PV bleeding
  • in-utero therapeutic interventions (transfusion, surgery)
  • and during delivery of a baby

An anti-D immunoglobulin injection is given in specific clinical situations in a standard dose. The Kleihauer test is performed to determine whether an additional dose is required.

The Kleihauer test may also be performed to detect if any foetal red cells are present in maternal circulation. It can also help to determine whether a FMH is involved when an intra-uterine death has occurred, regardless of the maternal blood group.

Cell free fetal DNA testing

Requests for this test from the Antenatal Clinic are referred to The International Blood Group Reference Laboratory (IBGRL) in Bristol. There is a turnaround time of 14 days upon receipt in the Blood Bank.

What is the purpose of cell-free fetal DNA test?

During pregnancy a small amount of cell-free fetal DNA is present in maternal blood. This DNA can be analysed to predict the baby’s Rh D blood group (Positive or Negative) as it assesses whether it differs from that of the mother. The test is highly accurate and can be performed from 11+2 weeks’ gestation (crown rump length less 45mm). However, owing to the sensitivity of the test, there is a small chance (0.1%) that a fetus predicted to be D negative will be D positive at birth.

Cold agglutinins

Cold agglutinins tests are not performed at Barnsley Hospital.

All samples are referred to the NHS Blood & Transplant Red Cell Immunohaematology Laboratory NHSBT, Barnsley.

What is the purpose of a cold agglutinins test?

The purpose of this test is to detect antibodies active at 4 oC. The two relevant cold antibodies most generally tested for are anti-I and anti-i.

Cold agglutinins seem to be produced at their highest levels in individuals between 11 and 25 years of age. They may be found in cases of atypical pneumonia especially where mycoplasma pneumonia is present.

Anti-i has been reported in patients with infectious mononucleosis, alcoholic cirrhosis and myeloid leukaemia.

If the antibody is able to bind to the red cells at 37 oC, then haemolysis may result, giving rise to CHAD -  Cold Haemagglutinin disease.

Histocompatibility & Immunogenetic testing

Histocompatibility and Immunogenetic (H&I) laboratories at NHSBT provide services related to:

  • solid organ and stem cell transplantation
  • platelet immunology
  • the provision of HLA or HPA selected products
  • transfusion reactions
  • the investigation of HLA related disease associations and granulocyte immunology

HLA (Human Leukocyte Antigen) typing

There are many thousands of different tissue types as a result of the differences in our HLA genes.

Some of these tissue types are associated with disease including:

  • ankylosing spondylitis

  • Behcet’s disease

  • birdshot chorioretinopathy

  • coeliac disease

  • narcolepsy

  • rheumatoid arthritis

  • selective IgA deficiency

Please contact the laboratory for sample requirements.

Emergency blood

Emergency blood will only be supplied at the request of medical staff who should liaise with the Blood Bank and accept full responsibility for un-cross matched blood issued.

Blood will either be group O Rh D Negative or Positive or type specific depending upon degree of urgency. Also see ‘Major Haemorrhage’.

Emergency Group O flying squad blood can be found on the top shelf of the cross-match fridge.

Decision To Transfuse

The decision to transfuse must be based on a thorough clinical assessment of the patient and their individual requirements and this should be documented in the patient’s case notes.

All requests for transfusion must provide a clear, unambiguous reason for transfusion. Terms such as ‘pre-op’, ‘anaemia’ or ‘low Hb’ alone are not acceptable and provide inadequate information for audit purpose.

Maximum Blood Order Schedule (MBOS)

A summary of the Maximum Blood Order Schedule (MBOS) can be found in the Hospital Transfusion Guidelines.

This is a guide to blood ordering for some surgical procedures. The guidelines have been approved by the Transfusion Committee and the surgical directorates.

Patient consent

Wherever possible, a trained and knowledgeable practitioner should inform the patient (or for a paediatric patient the person with parental responsibility), in a timely manner and in a way they can understand, of the reason for and also the risks, benefits and any alternatives to the transfusion.

Informed consent - either verbal or written - should be obtained wherever possible and documented in the patient’s case notes.

This webpage was reviewed and updated by Mark Taplin, Blood Transfusion Manager, 22nd February 2024


Source URL: https://www.barnsleyhospital.nhs.uk/pathology/blood-transfusion/test-turnaround

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