Blood Product Transfusion Thresholds
NICE guideline [NG24] Blood transfusion. Published: Nov 2015.
Red Blood Cell (RBC)
There are 3 main scenarios:
| Patient population / indication | Transfusion threshold | Haemoglobin target after transfusion |
|---|---|---|
| Restrictive transfusion (indicated in most patients, apart from those with major haemorrhage, ACS, or requiring regular transfusion) | 70 g/L | 70-90 g/L |
| Acute coronary syndrome* | 80 g/L | 80-100 g/L |
| Chronic anaemia requiring regular transfusions | Individualised thresholds and target should be used | |
| Major haemorrhage | This is because in major haemorrhage, transfusion is NOT guided by Hb levels, instead by clinical bleeding + massive haemorrhage protocols, not lab parameters. [Ref] | |
Patients with acute coronary syndrome have impaired coronary blood flow, and anaemia further reduces myocardial oxygen delivery. A higher haemoglobin threshold helps maintain oxygen supply and reduces the risk of ongoing ischaemia.
The transfusion threshold of 70 and 80 g/L is by far the most important things to learn. Post-transfusion targets are less important.
Transfusion with strict thresholds for haemoglobin level results in equivalent or better clinical outcomes compared to more liberal strategies, while significantly reducing transfusion rates and transfusion-associated complications. [Ref]
Platelet
There are 3 main scenarios.
1. Active Bleeding Patients (Therapeutic)
| Bleeding severity | Platelet count threshold |
|---|---|
| Clinically significant bleeding (WHO grade 2) | 30 x 109 / L |
| Severe bleeding (WHO grade 3 and 4) | 100 x 109 / L |
| Bleeding in critical sites (e.g. CNS, eye) |
Note: Platelet transfusion thresholds in active upper gastrointestinal bleeding differ slightly from the standard 30/100 rule.
According to NICE CG141, platelet transfusion should be offered if the platelet count is <50 ×10⁹/L in patients with active upper GI bleeding.
Apart from this modified platelet threshold, transfusion thresholds for other blood products remain unchanged. See the Upper Gastrointestinal (GI) Bleeding article for more information.
The WHO definitions of bleeding severity can be lengthy and difficult to memorise. For exam purposes, it is often easier to focus on the small number of situations that require a higher platelet threshold of 100 ×10⁹/L:
- Haemodynamic instability
- Fatal bleeding
- Bleeding in critical sites (e.g. CNS, eye)
If bleeding does NOT fall into one of these categories, it can generally be considered clinically significant bleeding, where a platelet threshold of 30 ×10⁹/L is used.
Note that this simplification is intended for exam revision (particularly SBA questions) and should not replace full clinical assessment in practice.
2. Before Invasive Procedure / Surgery (Prophylactic)
| Procedure / surgery type | Platelet count threshold |
|---|---|
| Most invasive procedures | 50 x 109 / L
Consider a higher threshold (50-75 x 109 / L) if there is a high risk of bleeding |
| Critical site surgery (e.g. neurosurgery, posterior eye) | 100 x 109 / L |
3. Stable Patients (NOT Bleeding and NOT Undergoing Invasive Procedure / Surgery)
Only transfuse if platelet count is <10 x 109 / L
Prophylactic platelet transfusion should NOT be given to patient with ANY of the following (even if platelet is <10 x 109 / L)
- Chronic bone marrow failure (e.g. aplastic anaemia, myelodysplastic syndrome, marrow infiltration by malignancy, marrow suppression by chemotherapy / radiotherapy)
- Autoimmune thrombocytopaenia (ITP)
- Heparin-induced thrombocytopaenia
- Thrombotic thrombocytopaenia purpura
Rationale:
- Prophylactic platelet transfusion is avoided in immune-mediated and consumptive thrombocytopenias because transfused platelets are rapidly destroyed or may worsen thrombosis
- In chronic marrow failure due to limited benefit and increased transfusion risks
In summary: if the patient is not actively bleeding and not undergoing a procedure or surgery, they are unlikely to benefit from prophylactic platelet transfusion.
Fresh Frozen Plasma (FFP)
The main indication for FFP transfusion is if there is:
- Clinically significant bleeding, and
- Abnormal coagulation (e.g. PT / APTT >1.5), and
- WITHOUT major haemorrhage (if major haemorrhage is present, the major haemorrhage protocol should be followed instead)
Prophylactic FPP transfusion can be considered in patients with abnormal coagulation who are having invasive procedures / surgery with a risk of clinically significant bleeding.
DIC is a common indication for FFP, but as stated above, FFP should only be given if there is clinically significant bleeding (or an invasive procedure planned).
FFP should NOT be used to correct abnormal coagulation in patients who are not bleeding and not having procedures.
Cryoprecipitate
The main indication for cryoprecipitate transfusion is if there is:
- Clinically significant bleeding, and
- Fibrinogen level <1.5 g/L, and
- WITHOUT major haemorrhage (if major haemorrhage is present, the major haemorrhage protocol should be followed instead)
Prophylactic cryoprecipitate transfusion can be considered in patients with fibrinogen level <1.0 g/L who are having invasive procedures or surgery with a risk of clinically significant bleeding.
FFP should NOT be used to correct fibrinogen levels in patients who are not bleeding and not having procedures.
Prothrombin Complex Concentrate (PCC)
The main use of PCC is to reverse the anticoagulation effect of warfarin in cases of major bleeding.
- PCC should be given together with IV vitamin K
- If PCC is not available → FFP can be given instead (but it is less effective)
- See the Warfarin article for more information