Haematology

Haematology is the study of blood and the treatment of blood-related pathologies. This involves performing analysis on patients' blood and its constituents to produce information which is used to identify a variety of haematological and haemostatic disorders. Within the Trust, there are two laboratories at Peterborough City Hospital and Hinchingbrooke Hospital, which provide five main Haematology services, as detailed below.  

Routine Haematology  

The Routine Haematology section deals primarily with Full Blood Count (FBC) tests, white blood cell differential, reticulocyte count, blood film examination and erythrocyte sedimentation rates. This section of the laboratory is highly automated with Sysmex analysers and integrated slide making/staining machines. The analysers produce accurate, reproducible cell counts and can automatically make and stain blood films when required. The annual workload from 2021-2022 across both sites was approximately 500,000 FBCs, 30,000 blood films and 79,000 ESRs. 

In addition to the above tests, the Routine Haematology departments also perform screens for the following diseases:

  • Malaria
  • Glandular fever
  • and Glucose-6-Phosphate Dehydrogenase (G6PD) deficiency screens

Coagulation  

The Coagulation section uses a wide variety of tests to investigate haemostasis - the body's ability to form blood clots in response to damage. There are three routine tests performed: 

  • The coagulation screen comprises a Prothrombin Time (PT) and Activated Partial Thromboplastin Time (APTT) test to investigate the extrinsic and intrinsic clotting pathways respectively, and also a Clauss Fibrinogen test and Thrombin time test may also be performed.
  • Patients on Warfarin have an INR test performed which is adapted for the patient's anticoagulated state
  • D-Dimers are performed to assess the degree of fibrinolysis occurring. They can be performed as either a negative predictive indicator for the pres ence of deep vein thrombosis/pulmonary embolism (DVT/PE) or as an aid to diagnose disseminated intravascular coagulation (DIC). 

Other specialised tests performed include low molecular weight heparin, Rivaroxaban, Apixaban and Edoxaban tests.

Haemoglobinopathies  

The Haemoglobinopathy section is involved in the detection of disorders of haemoglobin production; common haemoglobin variants e.g. Sickle cell and less common Thalassaemias. The primary method used to detect these disorders is High Pressure Liquid Chromatography (HPLC) and confirmation of the detected haemoglobin variant uses alternative methods, such as sickle solubility testing and haemoglobin electrophoresis. For more complex haemoglobinopathy studies patient samples can be referred to a reference centre for further investigation (Mass Spectrometry or DNA analysis). 

Flow Cytometry  

Flow Cytometry uses antibodies with a fluorescent tag to identify antigens (markers) that are specific to certain classes of blood cells. This is routinely used for five purposes: 

  • to monitor CD4+ lymphocytes in HIV-positive patients to monitor antiretroviral treatment
  • to identify the lineage of leukaemias and lymphomas in order to identify the most appropriate treatment regime
  • 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 foeto-maternal bleeding as part of the Kleihauer testing performed in the Blood Transfusion department. 

Molecular Haematology  

Real-time PCR techniques are used to identify genetic variants and mutations that can have haematological implications, for example the Factor V Leiden G1691A mutation which is associated with an increased risk of thrombosis.