What is the recommended time interval between Platelet-Rich Plasma (PRP) preparation and injection?

Recommended Time Interval Between PRP Preparation and Injection

PRP should be used within 4-6 hours after preparation when kept at room temperature, with optimal efficacy achieved when injected within 3 hours of preparation. 1, 2

PRP Preparation Process Overview

The preparation of Platelet-Rich Plasma (PRP) involves several critical steps that must be performed with precision to ensure optimal platelet viability and therapeutic efficacy:

1. Blood Collection:

   • Use citrate anticoagulant (ACD or CPD) instead of EDTA to prevent platelet swelling and activation 1
   • Process blood samples immediately after collection 3

2. Centrifugation Protocol:

   • First spin: 100-300g for 5-10 minutes (optimal: 170-200g for 10 minutes) 1, 4
   • Second spin: 400-700g for 10-17 minutes (optimal: 1500g for 15 minutes) 1, 4
   • Complete the entire preparation process within one hour of collection 1

3. Storage and Handling:

   • Keep at room temperature (20-24°C) 3
   • Avoid pneumatic tube transport which can significantly modify PRP parameters 3
   • Handle gently to prevent premature platelet activation 1

Critical Time Window for Injection

Research evidence clearly demonstrates that PRP bioactivity diminishes over time:

• Optimal window: Use within 3 hours after preparation 2
• Maximum limit: Up to 4-6 hours when kept at room temperature 1
• After 6 hours: Platelet functions become significantly altered 2

A study by BioResearch Open Access found that after 6 hours, platelet function was significantly compromised, affecting the therapeutic potential of PRP 2. This aligns with guidelines from the International Society on Thrombosis and Haemostasis that recommend completing PRP preparation within one hour of collection and using it within 4-6 hours 1.

Quality Control Considerations

Several factors can impact PRP quality and should be monitored:

• Platelet concentration: Target 1-1.5 million platelets/μL (3-5× baseline) 1, 4
• Leukocyte content: Low leukocyte count is preferable for pure PRP 2
• Activation status: Pre-activation is not always necessary; collagen-rich tissues may naturally activate PRP 3, 1

Common Pitfalls to Avoid

1. Improper anticoagulation: Never use EDTA as it causes platelet swelling and activation 1
2. Delayed processing: Don't exceed one hour between collection and completion of preparation 1
3. Improper storage: Avoid refrigeration at 4°C which damages platelets 1
4. Excessive delay before injection: Efficacy decreases significantly after 6 hours 2
5. Rough handling: Can cause premature platelet activation 1
6. Pneumatic tube transport: Significantly alters PRP parameters 3

Special Considerations

While some research suggests PRP might be stored at room temperature for up to 5 days with intermittent agitation in non-oxygen permeable containers 5, the strongest evidence supports using freshly prepared PRP within 3 hours for optimal therapeutic effect 2.

For clinical applications requiring standardized protocols, such as treatment of early knee osteoarthritis or tendinopathies, using freshly prepared PRP within the recommended time window is essential to ensure consistent therapeutic outcomes 6.