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

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 -20^oC for up to 12 hours  providing they have been preconditioned in a -80^oC freezer for 24 hours prior to use.

IMPORTANT: If sending samples to more than one department separate transport containers must be used. DO NOT package samples for different departments in the same container. This may lead to a loss of sample integrity when samples have to be unpacked and distributed to multiple departments.  

Address:

Transport containers should be specifically labelled to ensure they are delivered to the correct location:

Special Coagulation, Haematology Laboratory, Clinical Laboratory Services, Level -1, Queen Elizabeth Hospital Birmingham, Mindelsohn Way, Edgbaston, Birmingham, B15 2GW.  

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.