Indications for Blood Transfusion and Patient Blood Management

Indications for Blood Transfusion and Patient Blood Management

Study level: Clinical medicine, emergency medicine and pathology | Topic: Hematology and transfusion medicine

Learning objectives

• Decide when red cells, platelets, plasma, cryoprecipitate or factor concentrates are indicated.
• Apply restrictive, symptom-guided transfusion thresholds safely.
• Manage acute haemorrhage, obstetric bleeding, children, pregnancy, chronic anaemia and haemoglobinopathies.
• Use patient blood management (PBM) to prevent avoidable transfusion.
• Recognise when a low laboratory value is not an indication and when delay is dangerous.

1. The three questions before prescribing

1. What physiologic deficit exists? Oxygen-carrying capacity, platelet plug, fibrinogen or multiple clotting factors?
2. How urgent is it? Active haemorrhage/shock requires simultaneous resuscitation and source control; stable anaemia allows diagnosis and alternatives.
3. What is the smallest effective intervention? One component, one unit or a targeted factor may be safer than broad whole-blood exposure.

Situation	Transfusion decision
Stable, nonbleeding anaemia	Investigate and treat cause; consider red cells when symptoms or oxygen delivery impairment persist despite alternatives.
Active major haemorrhage	Activate a major-haemorrhage protocol, give balanced components/whole blood per local policy and control the source urgently.
Isolated abnormal INR without bleeding	Usually not an indication for plasma; treat the cause or use targeted reversal when appropriate.
Low platelet count without bleeding	Prophylactic platelet decisions depend on cause, trend, infection, fever and procedure risk; do not transfuse reflexively.

2. Red-cell transfusion

2.1 Major indications

• Acute blood loss with shock, ongoing bleeding or inadequate oxygen delivery.
• Severe symptomatic anaemia: syncope, myocardial ischemia, heart failure, hypoxia, confusion or severe exertional intolerance attributable to anaemia.
• Perioperative or obstetric blood loss when oxygen delivery cannot be maintained by haemostasis and fluid/blood-conservation measures.
• Chronic transfusion-dependent disorders such as thalassaemia major, selected marrow failure and sickle-cell indications under a specialist programme.
• Exchange transfusion or red-cell exchange for selected severe sickle complications or neonatal conditions under specialist protocols.

2.2 Thresholds as decision aids

For stable, nonbleeding adults, many guidelines consider a restrictive strategy around Hb 7 g/dL (70 g/L), with a higher trigger around 8 g/dL (80 g/L) in selected patients with cardiovascular disease or major surgery. These are not universal rules: symptoms, active ischemia, chronic adaptation, pregnancy, altitude, ongoing bleeding and local policy modify the decision. In a shocked patient, do not wait for a haemoglobin that may initially appear falsely reassuring.

2.3 One-unit reassessment

In a stable adult without active bleeding, prescribe one red-cell unit, reassess symptoms and vital signs, and repeat Hb before another unit when appropriate. A typical adult unit raises Hb by roughly 1 g/dL (10 g/L), but the response varies with bleeding, body size and fluid balance.

3. Platelet transfusion

Clinical situation	Common educational threshold/goal	Important caveat
Stable, nonbleeding hypoproliferative thrombocytopenia	Consider prophylaxis at <10 × 109/L.	Fever, sepsis, rapid fall, DIC and procedures may require different targets.
Clinically significant bleeding	Often target >50 × 109/L for major bleeding.	Treat the cause; platelet transfusion may be ineffective in immune destruction or TTP.
Neurosurgery/critical CNS or eye bleeding	Many protocols target >100 × 109/L.	Consult neurosurgery/haematology; thresholds vary by procedure and evidence.
Invasive procedure	Often target >50 × 109/L for high-risk procedures.	Low-risk procedures may need less; local policy governs.
ITP, TTP or HIT	Do not give routinely for the count alone.	Reserve for life-threatening bleeding or urgent procedure with specialist advice.

Platelet refractoriness requires assessment of post-transfusion increments, fever/sepsis, splenic sequestration and HLA/HPA antibodies; HLA-selected or crossmatched platelets may be needed.

4. Plasma transfusion

4.1 Appropriate indications

• Clinically significant bleeding with multiple coagulation-factor deficiency.
• Major haemorrhage with documented or anticipated factor depletion according to protocol.
• Urgent procedure with significant coagulopathy when a targeted factor or reversal agent is unavailable or unsuitable.
• Plasma exchange replacement in selected thrombotic microangiopathy (specialist protocol).

4.2 Inappropriate uses

• Volume expansion or hypoalbuminaemia alone.
• Correction of a mildly prolonged INR in a nonbleeding patient.
• Routine reversal when vitamin K, PCC or a specific antidote is the indicated treatment.
• Low fibrinogen when cryoprecipitate/fibrinogen concentrate is the targeted product.

Plasma has substantial volume and can cause allergy, TRALI and TACO. Reassess coagulation and clinical bleeding rather than chasing a laboratory number.

5. Cryoprecipitate and fibrinogen replacement

• Clinically significant bleeding with low fibrinogen, especially in obstetric haemorrhage, trauma, DIC or massive transfusion.
• Fibrinogen targets commonly lie around 1.5–2.0 g/L in active major bleeding, but the goal and product depend on local protocol and viscoelastic results.
• Use fibrinogen concentrate or cryoprecipitate according to availability, indication and specialist guidance.
• Do not use cryoprecipitate as a general treatment for anaemia or isolated prolonged PT/aPTT.

6. Major haemorrhage

6.1 Activation criteria

Activate a major-haemorrhage pathway for shock with ongoing bleeding, rapidly falling haemoglobin, uncontrolled obstetric/trauma/surgical haemorrhage or anticipated massive transfusion. Do not wait for laboratory confirmation when the patient is exsanguinating.

6.2 Priorities

1. Call the haemorrhage team, assign roles and obtain large-bore access or intraosseous access.
2. Control the source: pressure, tourniquet, pelvic binder, surgery, endoscopy, uterine intervention or interventional radiology.
3. Give balanced red cells/plasma/platelets or whole blood according to local protocol; tailor once laboratory/viscoelastic results return.
4. Monitor temperature, ionised calcium, potassium, pH, lactate, Hb, platelet count, PT/aPTT and fibrinogen.
5. Prevent hypothermia, hypocalcaemia and acidosis; avoid excessive crystalloid dilution.
6. Reassess after each cycle and stop protocol when bleeding is controlled and physiology is restored.

7. Special populations

7.1 Obstetric haemorrhage

Postpartum haemorrhage can deteriorate rapidly. Prepare group-and-screen early in high-risk pregnancy, use a major-haemorrhage pathway, monitor fibrinogen and treat uterine atony, retained tissue, genital tract injury or coagulopathy. Maternal resuscitation takes priority; involve obstetrics, anaesthesia, haematology and blood bank.

7.2 Children and neonates

• Calculate volume by weight and use paediatric/neonatal components; avoid adult assumptions.
• Consider prematurity, small circulating volume, congenital heart disease, bilirubin, potassium and CMV/GVHD product requirements.
• Use dedicated paediatric transfusion and monitoring protocols; confirm consent and parental/guardian communication.

7.3 Sickle-cell disease

Transfusion may be indicated for acute stroke, acute chest syndrome, splenic sequestration, severe symptomatic anaemia or planned surgery in selected patients. Avoid unnecessary transfusion because alloimmunisation and iron overload are significant; use phenotype-matched units and specialist haemoglobinopathy advice.

7.4 Thalassaemia and chronic transfusion

Regular transfusion supports growth and suppresses ineffective erythropoiesis in severe thalassaemia, but causes iron overload. Use extended antigen matching, monitor ferritin/organ iron and provide chelation under specialist care.

7.5 Cardiac/renal failure

Transfuse slowly with close fluid balance and consider diuretic strategy when appropriate; TACO risk is high. Do not withhold life-saving blood for fear of overload—monitor and support actively.

8. Patient blood management (PBM)

Pillar	Actions
Optimise the patient	Detect/treat iron, B12 or folate deficiency; manage inflammation; review anticoagulants; correct preoperative anaemia.
Minimise blood loss	Meticulous surgery, haemostasis, cell salvage, antifibrinolytic use when indicated, phlebotomy conservation and temperature control.
Harness tolerance of anaemia	Use physiologic triggers, restrictive single-unit reassessment and oxygen-delivery support while treating the cause.

PBM reduces exposure to transfusion reactions, infection, alloimmunisation, TACO and resource shortages. It does not mean delaying transfusion in shock or active life-threatening bleeding.

9. Consent and refusal

• Explain indication, expected benefit, common and serious risks, alternatives and the consequences of refusing.
• Document capacity, consent/refusal, emergency circumstances, product and special requirements.
• For patients who decline blood, involve senior clinicians early and document an agreed blood-conservation plan; emergency law and policy vary by jurisdiction.

10. Clinical cases

Case 1: stable iron-deficiency anaemia

A stable adult has Hb 6.8 g/dL but no ischemic symptoms or active bleeding. Consider a restrictive one-unit strategy while investigating and treating iron deficiency; reassess symptoms and Hb rather than automatically giving multiple units. Search for the source of blood loss.

Case 2: major trauma

A trauma patient is hypotensive with external bleeding and a normal initial Hb. The Hb may not yet reflect blood loss. Activate major haemorrhage, control the source, give balanced products and monitor calcium, temperature, coagulation and fibrinogen.

Case 3: low platelets before procedure

A patient with chronic liver disease has platelets 48 × 10⁹/L before a low-risk procedure and no bleeding. Do not automatically transfuse; discuss procedure risk, platelet function, portal hypertension and local threshold with the proceduralist/haematology team.

11. Quick self-test

1. Why is Hb alone insufficient in acute haemorrhage?
2. When might one red-cell unit be followed by reassessment rather than automatic repeat?
3. Which component is targeted to low fibrinogen?
4. Why is plasma inappropriate for isolated mild INR elevation without bleeding?
5. List three factors to monitor during massive transfusion.
6. Name the three PBM pillars.

Answers

1. Haemodilution and timing mean early Hb may be normal despite major blood loss; clinical shock and bleeding rate are more urgent.
2. In a stable, nonbleeding adult, reassess symptoms, observations and Hb after one unit to limit unnecessary exposure.
3. Cryoprecipitate or fibrinogen concentrate.
4. It adds volume and transfusion risk without correcting the cause; targeted reversal or observation may be safer.
5. Temperature, ionised calcium, potassium, pH/lactate, Hb, platelets, PT/aPTT and fibrinogen.
6. Optimise the patient, minimise blood loss and harness tolerance of anaemia.

Key take-home points

• Use red cells for inadequate oxygen delivery, platelets for platelet-related bleeding/procedure risk, plasma for multiple-factor deficiency and cryoprecipitate/fibrinogen for low fibrinogen.
• Thresholds are guides; symptoms, bleeding, ischemia, pregnancy, age and comorbidity matter.
• Never delay blood in exsanguinating haemorrhage while waiting for a laboratory threshold.
• PBM reduces avoidable transfusion while preserving rapid access to life-saving components.
• Document indication, product, consent, reassessment and reaction monitoring every time.

Selected references

• WHO: Patient blood management and clinical use of blood
• WHO: The Clinical Use of Blood
• WHO: Blood transfusion safety
• JPAC: Guidelines for the UK Blood and Tissue Services