Perioperative Anaemia & Patient Blood Management

• Anaemia is a poor prognostic factor, with an increase in post-operative complications of up to 20%

• 2017 international consensus statement suggests both sexes should have a threshold of 130g/L to define anaemia


• Acceptance of lower [Hb] for women pre-operatively could lead to an increased risk of poorer outcomes (BJA, 2023)
• Women are generally smaller and have lower circulating blood volumes, but have the same physiology of bleeding from surgery
• Women with [Hb] 120 - 129g/L have greater perioperative complications than those with [Hb] >130g/L, including LOS and need for transfusion

• Men: <130g/L
• Women: <120g/L
• Pregnant women: <110g/L

Patient blood management is the care of people at risk of transfusion, not necessarily those who will receive a transfusion

• Patient blood management (PBM) aims to improve patient safety and outcome, in part by avoiding unnecessary blood transfusion
• It is an MDT, evidence-based approach adopted by the WHO and recommended by NICE and NHSBT


• Patient blood management is associated with lower rates of red cell transfusion (BJA, 2023) and potentially other benefits such as:
• Reduced complication rates and lower mortality
• Improved patient outcomes
• Being at least cost-effective if not cost-saving
• Effects may be more pronounced in centres performing complex surgeries in higher risk patients, or in surgical specialties typically associated with higher transfusion rates (BJA, 2023)


• PBM is based on the core tenets of:
1. Identification and correction of anaemia
2. Minimising bleeding and blood loss
3. Harnessing patient-specific tolerance when managing anaemia

• As per NICE Guidelines, the presence of anaemia (i.e. a full blood count) should be checked in:
• Any patient undergoing major surgery
• Patients undergoing intermediate surgery who are ASA 3/4
• Patients undergoing surgery where estimated blood loss is ≥500ml (or 10% blood volume)


• Assess for anaemia at least 4 - 6 weeks prior to surgery to allow adequate time for treatment
• Ideally check at time of surgical referral or surgical booking (median 43 days prior to surgery)
• Often too late by the time of anaesthetic pre-assessment (median 21 days prior to surgery)

• Perioperative anaemia is multifactorial, including the effects of age, nutritional status, existing (chronic) comorbidities, inflammatory states and pregnancy
• See the physiology of anaemia page for a more detailed list of aetiologies and investigations


• If identified, anaemia should be further evaluated as to its aetiology using blood tests alongside factors from the history
• This involves sending bloods for iron studies (ferritin, transferrin saturations), vitamin B₁₂/folate levels, CRP and U&E


• The results of these tests allow stratification of patients into different broad categories to aid ongoing management:
1. Iron deficiency anaemia → ferritin <30μg/L or transferrin saturations <20%
2. Iron deficiency anaemia + functional iron deficiency → ferritin 30-100μg/L + CRP <5mg/L OR eGFR <60ml/min
3. Functional iron deficiency → ferritin >100μg/L + transferrin saturations <20% ± raised CRP
4. Vitamin B₁₂/folate deficiency → ferritin >100μg/L + transferrin saturations >20% + low vitamin B₁₂ or folate levels
5. Other cause of anaemia → ferritin >100μg/L + transferrin saturations >20% + normal vitamin B₁₂ or folate levels
• Examples include CKD, thyroid disease, malignancy, drug-induced or other causes

• Surgery should be scheduled to correspond with optimised red cell mass
• Major, non-urgent surgery should be delayed to allow diagnosis and treatment of anaemia
• Requires MDT coordination involving Anaesthetic and Surgical teams, Haematology, pre-assessment teams, dieticians/nutritional input

• Management of IDA (categories 1 & 2 above), with or without functional iron deficiency, should be with iron replacement therapy
• Oral iron salts
• Historical preparations poorly tolerated
• Newer formulations with higher bioavailability and tolerability may provide more effective and expedient supplementation


• At least 6 weeks required to adequately replace iron stores and red cells mass due to poor bioavailability
• Recheck Hb after 4 weeks; if not responding or intolerant then use IV iron instead


• Alternate day dosing now felt to be superior to previous higher dose (BD or TDS) regimens
• Higher doses increase hepcidin levels
• This paradoxically reduces the amount of iron absorbed from the GI tract
• The consequence of this is both reduced efficacy with respect to iron replacement and increased side effects from unabsorbed iron
• Provide nutritional support and encourage vitamin C intake to maximise iron absorption


• Intravenous iron infusion
• Faster and better tolerated than oral iron repletion
• Latest preparations have fewer adverse effects than historical preparations
• May lead to acceptable haemoglobin responses in as little as 2 weeks
• May reduce perioperative red cell transfusion rate by as much as 15-20%, although this view was challenged by the (methodologically suspect) PREVENNT Trial
• Associated with improved morbidity, mortality, patient outcomes and hospital outcomes

• Patients with B₁₂ or folate deficiency (category 4 above) should have these replaced


• Patients with pure functional iron deficiency (category 3 above) should be clinically reviewed, treated with iron replacement therapies as above ± referred to Haematology for consideration of EPO


• Patients with other causes of anaemia (category 5 above) should be clinically reviewed ± referred to Haematology for further evaluation

• This is based on the use of blood conservation strategies, which should be planned in advance in a patient-specific fashion

• Patients' cardiopulmonary reserve should be optimised pre-operatively to improve tolerance of blood loss/anaemia
• Intra-operative oxygenation/ventilation and cardiac output should also be optimised

• Minimise oxygen demand e.g. appropriate multi-modal opioid-sparing analgesia to reduce pain, temperature management
• Maximise oxygen delivery e.g. supplemental oxygen titrated against suitable endpoints
• Support adequate organ perfusion e.g. with vasopressors
• Evidence-based transfusion thresholds and strategies should be used e.g. single unit transfusions, target >70g/L or >80g/L if history of ischaemic cardiac disease
• Avoid infection, and treat promptly if present
• Appropriate nutrition ± supplements should be used to help recovery