How many units of Fresh Frozen Plasma (FFP) should be transfused for a prolonged Activated Partial Thromboplastin Time (APTT)?

FFP Dosing for Prolonged APTT

For a prolonged APTT with active bleeding, transfuse 4 units of FFP initially (approximately 10-15 ml/kg), which provides roughly 1000 ml for an average 70 kg adult. 1, 2

Clinical Context Determines FFP Administration

The decision to transfuse FFP for prolonged APTT depends critically on whether the patient is actively bleeding:

Active Bleeding with Prolonged APTT

• Initial dose: 4 units of FFP (approximately 1000 ml or 15 ml/kg) 1, 2
• This dose is necessary to achieve the minimum 30% concentration of plasma factors required for hemostasis 2, 3
• Each FFP unit contains approximately 250-300 ml 2
• Maintain 1:1 ratio of RBC:FFP if massive transfusion is ongoing until coagulation results are available 1

No Active Bleeding

• Do not transfuse FFP solely to correct laboratory values 1, 4
• FFP transfusion in non-bleeding patients with mild-moderate coagulation abnormalities does not prevent bleeding and increases transfusion-related complications 2, 4
• Studies demonstrate that FFP fails to correct PT in 99% of patients with mild coagulation abnormalities 5

Specific Clinical Scenarios

Obstetric Hemorrhage

• Withhold FFP until 4 units of RBC have been transfused, unless early coagulopathy is diagnosed on coagulation testing 1
• APTT prolongation is uncommon in postpartum hemorrhage, affecting only 1% of hemorrhages at 1000 ml and typically occurring after >4000 ml blood loss 1
• After 4 units RBC with ongoing bleeding: give 4 units FFP and maintain 1:1 ratio until coagulation results available 1

Major Trauma

• Replacement of coagulation factors during major hemorrhage is a primary indication for FFP 1, 3
• APTT >2 times normal with microvascular bleeding warrants FFP transfusion 1, 3

Disseminated Intravascular Coagulation (DIC)

• FFP indicated for acute DIC with bleeding 1, 3
• PT and APTT prolongation beyond that expected by dilution, with thrombocytopenia and fibrinogen <1.0 g/L, suggests DIC 1
• Administer FFP sooner rather than later in sufficient dosage to avoid progression 1

Critical Dosing Thresholds

APTT must be >1.5 times normal (or >2 times normal per some guidelines) with active bleeding to justify FFP transfusion 1:

• PT >1.5 times mean normal value correlates with increased risk of clinical coagulopathy 1
• INR >1.5 with active bleeding is an indication 1, 3
• Doses below 10 ml/kg are unlikely to achieve the 30% factor concentration threshold needed for hemostasis 2

Important Caveats

Prioritize Fibrinogen Replacement

• Hypofibrinogenaemia is the most common factor deficiency, occurring before APTT prolongation 1
• If fibrinogen <1.5 g/L (or <2 g/L in obstetrics), prioritize cryoprecipitate over FFP 1
• Four units of FFP contain only approximately 2 g of fibrinogen, whereas two pools of cryoprecipitate (10 units) contain at least 4 g 1

Recheck Coagulation Parameters

• Repeat coagulation tests after FFP transfusion to determine need for additional doses 2
• Laboratory turnaround time may necessitate requesting components before results are available in rapid bleeding 1

Avoid Common Pitfalls

• Do not use FFP for volume replacement - this is not an indication 1, 4
• Do not transfuse prophylactically in non-bleeding patients with isolated APTT prolongation 1, 4
• In liver disease patients without bleeding, FFP does not correct PT and exposes patients to unnecessary risks including TRALI and circulatory overload 4