Disposable Vacuum Blood Collection Tube – PT Tubes (Citrate Tubes)

Disposable vacuum blood collection PT tubes are specially designed for coagulation testing, particularly for measuring Prothrombin Time (PT), Activated Partial Thromboplastin Time (APTT), and other clotting parameters. These tubes are essential tools in hematology laboratories, hospitals, and clinical diagnostic centers.

Structure and Composition
PT tubes are made from high-quality PET or glass material and are pre-filled with a precise concentration of 3.2% or 3.8% sodium citrate anticoagulant. The inner wall of the tube is coated evenly to ensure accurate blood-to-anticoagulant ratio, typically 9:1. The tubes are vacuum-sealed to automatically draw a fixed volume of blood, ensuring consistency and reducing the risk of contamination.

Each tube is equipped with a color-coded light blue cap that identifies it as a coagulation tube. The rubber stopper ensures airtight sealing, while the internal vacuum maintains sample integrity during collection, transport, and storage. Tubes are available in various draw volumes, usually ranging from 1.8 ml to 4.5 ml.

Working Principle
Sodium citrate acts as a reversible anticoagulant by binding to calcium ions in the blood, preventing clot formation. During laboratory analysis, calcium is reintroduced to initiate clotting, allowing precise measurement of coagulation parameters. The accuracy of results heavily depends on the correct blood-to-additive ratio, which PT tubes are designed to maintain.

PT tubes are widely used in:

Prothrombin Time (PT) Test:
This test measures how long it takes for a clot to form in a blood sample. It's a key indicator of the extrinsic and common pathways of the coagulation cascade, which are involved in blood clotting. 

International Normalized Ratio (INR):
The PT test results are often used to calculate the INR, a standardized way to report PT results, allowing for easier comparison across different labs and test methods. 

Monitoring Anticoagulant Therapy:
PT/INR tests are essential for monitoring patients on anticoagulant medications like warfarin, ensuring the medication is effectively thinning the blood without causing excessive bleeding. 

Diagnosing Bleeding Disorders:
PT tests can help identify potential bleeding disorders by revealing deficiencies in clotting factors or other abnormalities that affect the clotting process. 

Coagulation Testing:
Besides PT, these tubes can be used for other coagulation tests that assess different aspects of the clotting process. 

Proper Blood Collection:
Light blue top tubes contain sodium citrate, which acts as an anticoagulant to prevent the blood from clotting prematurely in the tube. It's important to collect the blood properly and follow specific guidelines for blood collection to ensure accurate test results

They are suitable for use with both manual and automated analyzers. Proper mixing (usually by gentle inversion 5-8 times) is essential immediately after blood collection to prevent clotting inside the tube.

In summary, PT tubes provide a reliable, sterile, and convenient solution for coagulation studies. Their precise formulation and vacuum-sealed design ensure accurate and reproducible results in clinical diagnostics.