Preferred Sample Type

Bethesda / Inhibitor Assay (Human, Porcine and Bovine Chromogenic)

Bethesda / Inhibitor Assay (Human, Porcine and Bovine Chromogenic)

Specimen Volume

2 x 3.5 mL (Vacuette tubes) or 2.7mL (BD Vacutainer tubes)

Specimen Transport

Standard transport to laboratory - State for the attention of Special Coagulation on request form

Sample Preparation

Samples must be filled to the black fill line (Vacuette tubes) or the frosted line (BD Vacutainer tubes) indicated on the sample tube. Any sample filled above or below this level will be rejected and a repeat sample will be required

Turnaround Time

21 days

Sample Processing In Laboratory

Sample should be centrifuged

Sample Stability

12 hours from venepuncture (ideally received no later than 4 hours after collection)

General Information

External Requests:

Note: For external requests please click Here for Coagulation Disorders request form. Please complete all information fully.

Sample packing and transportation:

Frozen plasma should be sent on dry ice using an insulated container to ensure that it remains frozen during transport. Please refer to the preanalytical variables section of the BSH guidelines on the laboratory aspects of assays used in haemostasis and thrombosis1.

As an alternative the bio-freeze container system can be used to ensure samples remain frozen in transit. These have been locally validated to maintain samples at -20oC for up to 12 hours  providing they have been preconditioned in a -80oC freezer for 24 hours prior to use.

Disclaimer:

Please note failure to use an appropriate transit container may affect sample integrity, thus the accuracy of results cannot be guaranteed.  Furthermore, samples packaged incorrectly that arrive in a thawed state cannot be tested.

Please contact the laboratory on 0121 371 5988 (Queen Elizabeth Hospital) if you require any further information.

1) Baker, P., Platton, S., Gibson, C., Gray, E., Jennings, I., Murphy, P., Laffan, M. and British Society for Haematology, Haemostasis and Thrombosis Task Force (2020), Guidelines on the laboratory aspects of assays used in haemostasis and thrombosis. Br. J. Haematol., 191: 347-362.

https://doi.org/10.1111/bjh.16776

Samples that meet the following criteria will not be processed:

  • Haemolysed, clotted, underfilled or overfilled samples.
  • Samples >12 hours old from the time of collection.
  • Samples received from other hospital laboratories that have been frozen and thawed.
  • Samples which fail the minimum data set.

Samples that meet the following criteria will not be processed:

  • Haemolysed, clotted, underfilled or overfilled samples.
  • Samples >12 hours old from the time of collection.
  • Samples received from other hospital laboratories that have been frozen and thawed.
  • Samples which fail the minimum data set.

Assay Limitations:

  • If a patient has been treated with blood products e.g. factor concentrate, FEIBA, etc before performing coagulation inhibitor assays this should be taken into consideration when interpreting the data obtained.
  • It may also be useful to perform a lupus inhibitor screen when dealing with a suspected acquired coagulation factor inhibitor.

Patients on Emicizumab:

  • Inhibitor levels for patients treated with Emicizumab are processed using the Bovine Chromogenic Bethesda assay. Please clearly indicate on the request form if the patient is on Emicizumab. Note all positive samples are currently sent to Royal Hallamshire Hospital, Sheffield for confirmation.

 

Reference Range

<0.6 BU/mL

Specifications

  • EQA Status: ECAT
  • EQAS Scheme: Yes

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