Preoperative anaemia, even when mild, is a major risk factor for perioperative complications.

The prevalence of anaemia in patients presenting for major non-cardiac surgery is 27% in women and 31% in men.

Correction of preoperative anaemia is a key 'pillar' of a perioperative patient blood management strategy aiming to mitigate the effects of surgical blood loss and reduce later transfusion requirements with their additional associated hazards.

Early preoperative identification of anaemia on full blood count is crucial. Once detected, the underlying cause should be identified to facilitate management.

In some cases, anaemia may be the reason behind the operation itself but this should not deter maximum efforts to normalise haemoglobin by time of surgery.

Anaemia and Perioperative Risk

Anaemia impairs the ability of the patient to withstand the surgical stress response through a much reduced ability to deliver oxygen to the tissues when demand is greatest.

Preoperative anaemia results in the following elevation in perioperative risk:

  • 50-300% increase in 30 day mortality
  • 30-50% increase in postoperative cardiorespiratory complications
  • 20-30% increase in wound complications
  • Increased transfusion requirements and length of stay

Causes of Preoperative Anaemia

A range of factors may contribute to preoperative anaemia including;

  • Poor diet leading to iron deficiency
  • Occult loss from an undiagnosed malignancy
  • Occult GI loss including the effects of antiplatelet medication
  • Anaemia of chronic disease

Iron deficiency is the most common explanation through either insufficient intake or occult haemorrhage.

See 'Management of Preoperative Anaemia' for more information about investigation and management of the underlying cause.

Management of Preoperative Anaemia

In the majority of cases, iron supplementation will be required. In some cases preoperative intravenous iron replacement may be required.

Use NHS Lothian Preoperative Anaemia Pathway to guide decisions around timing of non-urgent surgery, investigation and treatment.