About Our Service
Haematology is the study of blood and the treatment of blood related pathologies. The department performs analyses on patients' blood and its constituents, to produce information which is used to identify a variety of haematological and haemostatic disorders. The laboratory is split into five main sections detailed below, each focussing on a different area of haematology.
The Routine Haematology section deals primarily with Full Blood Counts (FBCs), WBC differential, reticulocyte count, NRBC, blood film examination and ESRs. The section is highly automated with two Sysmex XN-10 analysers and two Sysmex XN-20 analysers, integrated slide making/staining and ESR analysis. The analysers produce accurate, reproducible cell counts, and will automatically make and stain blood films for those samples which match rule base criteria (Any that are not made automatically can quickly be made manually should the need arise). When the results are transferred to the host computer those that are within the reference range, are not significantly different from previous results and are not marked by the analyser as requiring specific attention are authorised automatically. Those that are not authorised automatically are placed on a list to be vetted by a registered Biomedical Scientist. Decisions are then made whether to authorise, examine a blood film, generate other investigations, repeat the analysis or refer to a Consultant Haematologist. The annual workload from 2017-2018 was approximately 405,000 FBCs, 27,200 blood films and 84,800 ESRs.
In addition to the above tests, the Routine Haematology department also performs manual paediatric ESRs, haptoglobin assays, and screens for the following: Malaria (both by film investigation and rapid kit method), glandular fever, and Glucose-6-Phosphate Dehydrogenase (G6PD) deficiency.
As part of routine service provision for clinic point-of-care testing, we also maintain a Sysmex XN-550 analyser in Peterborough City Hospital and a Sysmex XS-1000i analyser in Stamford Hospital.
The Coagulation section uses a wide variety of tests to investigate haemostasis - the body's ability to respond appropriately to damage by forming clots until the damage is repaired. All fully automated tests are performed on Instrumentation Laboratory ACL TOP 500 analysers, with manual tests performed on an Amelung KC4 analyser. There are three tests that are most routinely performed throughout the day:
· The most common routine test is the coagulation screen which comprises of a Prothrombin Time (PT) and Activated Partial Thromboplastin Time (APTT) test, investigating the extrinsic and intrinsic clotting pathways respectively, and also a Clauss Fibrinogen. A Thrombin time is also performed as part of the coagulation screen. The PT and APTT can be performed separately to match the requirements for certain investigations.
· Patients on Warfarin have a special PT test (Denoted INR) which while being the same test as the PT has different reference ranges to accommodate for the patient's anticoagulated state (patients on Heparin are similarly monitored using an APTT test with different reference ranges).
· D-Dimers are performed to assess the degree of fibrinolysis occurring. They are performed for two reasons: To act as a negative predictive indicator for the presence of deep vein thrombosis or pulmonary embolism (DVT/PE), and as an aid to diagnose disseminated intravascular coagulation (DIC).
Specialist tests such as lupus anticoagulants are run weekly whereas other specialist tests such as factor deficiency assays (including von Willebrand) and thrombotic screens are routinely performed once enough samples have been received for a batch to be run (usually every two weeks or sooner depending on size number), though if a sample needs testing urgently, the batch run can be brought forward. Low molecular weight heparin, Rivaroxaban and Apixaban assays are run as and when required.
Results within expected ranges are authorised automatically in a similar fashion to Routine Haematology, with those outside the ranges being vetted by a registered Biomedical Scientist to decide how best to continue the investigation. All specialist tests are vetted before authorisation. The annual workload from 2017-2018 was approximately 58,800 coagulation screens, 12,600 INRs and 7,000 D-Dimers.
The Haemoglobinopathy section is involved in the detection of disorders of haemoglobin production, both detection of the more common haemoglobin variants (for example Sickle cell) and the Thalassaemias. The primary method used to detect these disorders is High Pressure Liquid Chromatography using the Biorad Variant 2 analyser. Confirmation of the detected haemoglobin variants is by investigation using alternative methods, such as Sickle Solubility testing and Haemoglobin electrophoresis. For more complex haemoglobinopathy studies patients samples can be referred to a reference centre for further investigation (Mass Spectrometry or DNA analysis).
Samples are typically investigated for haemoglobinopathies under four circumstances:
· When FBC or blood film results imply the potential presence of a haemoglobinopathy.
· When an urgent determination is necessary, such as a potential sickle carrier going into theatre.
· When other HPLC-based haemoglobin investigations detect abnormal variants.
· As part the antenatal screen (family origin testing protocol) as instigated by the NHS Sickle Cell and Thalassaemia Screening Programme.
Urgent samples can be processed as and when necessary for HPLC and Sickle Solubility. Routine samples are processed on weekdays, Monday to Friday. Electrophoresis is performed as and when there are sufficient samples to run a batch (usually every three to four weeks).
The annual workload from 2017-2018 was approximately 5,000 Haemoglobinopathy screens.
The Flow Cytometry section uses antibodies with a fluorescent tag to identify antigens (markers) that are specific to certain classes of blood cells; the identity of the type of cells present is based on their positivity or negativity for those markers. This is used routinely for five purposes:
· To monitor CD4+ lymphocytes in the peripheral blood of known HIV-positive patients, to gauge how effectiveness of their antiretroviral treatment.
· To identify the lineage of leukaemias and lymphomas in order to allow the most appropriate treatment regime to be selected.
· To identify the presence of HLA-B27.
· To evaluate the T & B subset composition of a patient's lymphocyte population.
· To accurately measure the degree of foetomaternal bleeding as part of the Kleihauer testing performed in the Blood Transfusion department.
It can also be used to tag platelet markers, allowing a platelet count to be obtained via a different method than that on the FBC analysers.
The analyser in current use in Flow Cytometry is the Beckman Coulter Navios Flow Cytometer.
Flow cytometry is not routinely performed outside normal working hours. Leukaemia/lymphoma panels and T & B subsets are performed individually as and when received, while CD3/4/8 HIV monitoring panels are performed together every 24 to 48 hours. HLA-B27 analysis and Foetomaternal bleed estimation are performed daily (up to midday on Fridays).
The annual workload from 2017-2018 was approximately 700 HLA-B27.
The Molecular Haematology section uses real-time PCR techniques to identify genetic variants and mutations that can have haematological implications. Currently we use the GeneXpert DX systems to test for the following mutations:
· Factor V Leiden G1691A and Prothrombin G20210A – These are associated with an increased risk of thrombosis.
Any tests that cannot be performed at PCH are sent to referral laboratories for analysis.
The Haematology department currently consists of Biomedical Scientist staff, Assistant Technical Officers and six Consultant Haematologists. Clinical advice (including choice of test, interpretation of results, diagnostic, prognostic or other information) is available from the department on a 24/7 basis. This will be provided by a Consultant Haematologist on a rota basis. The laboratory's team of Biomedical Scientists can provide information on requesting, specimen collection, interferences, validity of results, biological variation and additional testing. Please see the Service Hours section for contact details.