In phlebotomy, timing and technique are very important. One of the most critical, and often misunderstood aspects of a blood draw, is the proper use and removal of the tourniquet.
This simple elastic band plays a vital role in venous access, but improper timing in its removal can compromise test results or patient comfort. So, when exactly should you remove the tourniquet during a blood draw?
Let us explore the purpose of the tourniquet, best practices for removal, and the reasoning behind it.
What Is a Tourniquet and Why Is It Used?
A tourniquet is typically a stretchable band made of latex or another flexible material. It’s tied snugly around the upper arm to temporarily restrict venous blood flow, causing the veins below it to become more prominent and easier to access with a needle.
Its primary purposes are:
- To make veins more visible and palpable
- To engorge veins, which helps with needle insertion
- To increase success rates on the first attempt at venipuncture
However, the tourniquet should only be used briefly, ideally for no more than one minute. Prolonged application can cause complications.
When Should the Tourniquet Be Removed?
According to the Clinical and Laboratory Standards Institute (CLSI) and other accepted phlebotomy guidelines, the tourniquet should be removed as soon as blood flow is established, that is, once blood begins to fill the first tube or syringe.
Here’s a step-by-step guide for context:
- Apply tourniquet 3–4 inches above the selected venipuncture site.
- Locate and clean the vein.
- Insert the needle into the vein.
- Confirm blood flow — this means blood is entering the collection device or tube. Wait a little to ensure blood flow is continuous (sometimes blood can stop flowing).
- Immediately release the tourniquet.
- Continue drawing the necessary volume of blood.
- Remove the needle after final draw, then apply pressure and bandage the site.
Why Is Timing Important?
For many things in life timing is crucial. It is no different when using the tourniquet. Leaving it on too long can cause several issues, like:
1. Hemoconcentration
When blood flow is restricted for too long, plasma (the liquid portion of blood) begins to leak from the veins into surrounding tissue. This concentrates the blood cells and certain analytes, like proteins, potassium, calcium, and enzymes — leading to falsely elevated test results.
2. Hemolysis
Prolonged pressure can increase the risk of hemolysis — the breakdown of red blood cells — which may render the sample unusable or lead to inaccurate results. In such cases the sample may need to be retaken.
3. Patient Discomfort
Extended use of the tourniquet can cause pain, bruising, or tingling sensations. Prompt removal after needle insertion minimizes discomfort and promotes better circulation.
Some Common Mistakes to Avoid
- Waiting too long to release: Some phlebotomists wait until all tubes are filled before removing the tourniquet. This is a bad habit and should be avoided.
- Tying the tourniquet too early: Don’t tie it and then spend several minutes searching for a vein or preparing equipment. Prepare your equipment first and survey the venipuncture area for a vein before tying the tourniquet. Also, you can even apply the tourniquet to find a vein so that you already know where to locate the vein.
- Reapplying it repeatedly: If the draw is unsuccessful and you need to try again, allow the patient’s circulation to normalize before reapplying the tourniquet.
Special Situations
In certain cases — such as with difficult veins or when using a butterfly needle for multiple tubes — the phlebotomist may be tempted to leave the tourniquet on longer to maintain vein firmness. While occasional slight delays are understandable, the one-minute rule should still guide decision-making. When in doubt, always prioritize specimen integrity and patient safety.
Conclusion
The tourniquet is a valuable tool for drawing blood, but like all tools, it must be used properly. The key takeaway? Remove the tourniquet as soon as blood begins to flow into the collection tube. I would add to wait a little, though, to make sure that the flow is continuous and that the blood hasn’t stopped.
This small but crucial step helps ensure accurate test results, patient comfort, and adherence to phlebotomy standards. So, whether you’re a new student or a seasoned healthcare worker, when it comes to the use of the tourniquet, remember: timing is important., remember: timing is important.