Clinical Review

ABC of clinical haematology: Haematological emergencies

BMJ 1997; 314 doi: (Published 03 May 1997) Cite this as: BMJ 1997;314:1333
  1. Rebecca Frewin,
  2. Andrew Henson,
  3. Drew Provan


    Patients with both malignant and non-malignant haematological disease may present with dramatic and often life threatening complications of their diseases. This article deals with five of the most common emergencies encountered by haematologists. Although these conditions are not seen commonly in day to day clinical practice, recognition of the underlying pathological processes is important in determining the likely cause of the abnormalities and is helpful in determining the specific treatment needed.

    General physicians must be able to recognise and start basic treatment, which may be life saving, in patients presenting with haematological emergencies

    Hyperviscosity syndrome

    This may be caused by several haematological conditions. Blood viscosity is a function of the concentration and composition of its components. A marked increase in plasma proteins (for example, monoclonal immunoglobulin in myeloma) or cellular constituents (for example, white blood cells in acute leukaemia) will raise the overall blood viscosity. This leads to sludging of the microcirculation and a variety of clinical manifestations. Hyperviscosity may present insidiously or acutely with neurological symptoms and signs.

    Fundal changes in patient with hyperviscosity (newly diagnosed myeloma with IgA concentration of 50 g/l).

    Causes of hyperviscosity

    • Myeloma (especially IgA)

    • Waldenström's macroglobulinaemia (IgM paraprotein)

    • Polycythaemia

    • High white cell count (hyperleucocytosis)

    Blood viscosity will often be more than four times the normal viscosity before symptoms occur. Patients with chronic disorders such as polycythaemia and myeloma are often physiologically well compensated for the degree of hyperviscosity and may complain only of mild headaches. In contrast, patients with acute leukaemia and a high white cell count may present in extremis; they become hypoxic from pulmonary involvement and are often obtunded, with a variety of neurological signs. Prompt treatment is needed to prevent permanent deficits. Elderly patients with impaired left ventricular function may experience decompensation due to their hyperviscosity, resulting in increasing congestive cardiac failure.

    Blood film in patient …

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