Haematology Tests

Bone marrow examination
Coagulation investigations
Specimen collection (including ‘Maximum Times for Add-on Requests’)
HIV Monitoring (CD4 & HLA-B27 Testing Advice

Bone marrow examination

Indications for bone marrow examination should be discussed with the Consultant Haematologist.

Coagulation Investigations

The initial investigation of a Patient with a bleeding tendency should comprise: –
Full Blood Count ( includes platelets ),
Prothrombin Time ( PT )
Partial Thromboplastin Time ( APTT )
If DIC is suspected, Fibrinogen and D-Dimers should be added.  Further investigation should be discussed with the Consultant Haematologist.
Heritable Thrombophilia – Guidelines for Testing
Recommendations of who should be investigated for inherited thrombophilia can be found here. If there are any concerns about the eligibility for testing, please discuss with a Consultant Haematologist, ext 3198 (01271 349198).


Clinical advice relating to anticoagulation management can be found in the Trust’s Oral Anticoagulation Policy and referenced documents within that policy.

HIV Monitoring and HLA-B27 Testing

HIV monitoring testing is by way of CD4 counts only. For clinical advice in respect of when and how to request these tests and how to interpret the results please contact Consultant Immunologist, Derrifird Hospital Plymouth, Dr Claire Bethune claire.bethune@nhs.net. The contact in North Devon is Dr Elizabeth Claydon:- elizabeth.claydon@nhs.net.

Please note that whilst the laboratory issues CD4 count results with a reference range we do not provide ‘High’ or ‘Low’ flags against results at the request of Dr Claydon.

HLA-B27 testing: For clinical advice in respect of when and how to request this test and how to interpret the results please contact Consultant Rheumatologist, North Devon District Hospital, Dr Stuart Kyle stuartkyle@nhs.net

Specimen Collection

Blood specimen tube guides are available here.

General specimen collection information can be found here.

Time Limits for Requesting Additional Examinations

Maximum times for Add-on Requests – Haematology Samples
Add-on testPrimary sample requiredMax. time post sampling
Plasma ViscosityPurple tube4 days
Blood filmPurple tube1 day
Malaria screenPurple tube4 hours
Reticulocyte countPurple tube12 hours
G6PDPurple tube4 days
Hb electrophoresisPurple tube4 days
Glandular fever screenPurple tube/Gold tube24 hours/4 days
Cell markersPurple tube12 hours
APTTBlue tube4 hours
D DimerBlue tube24 hours
GHBPurple tube4 days
Coag screenBlue tube4 hours
IF AntibodiesGold tube4 days


Maximum Times for Add-on Requests – Blood Transfusion Samples
All Blood Transfusion samples are retained for 7 days. However, the issue of blood against a Group & Save sample is dependent on recent transfusion history. Please see the Blood Transfusion Policy or contact the Transfusion Laboratory for further details.

Last updated: July 16, 2021