The converse is true in anemic animals, in which a sample may clot due to undercitration. Severe hemoconcentration can result in overcitration of the plasma, which will falsely prolong clotting times (especially the APTT).

The hematocrit of the patient should be considered.

If clean venipuncture is achieved and there is anticoagulant in the syringe, this is not necessary.

There is controversy on the need to discard the first few ml of blood.

Only short butterfly catheters (3″) should be used for blood draws. Long butterfly catheters are used for sample collection and slow sample draws can be problematic. This is achieved with the above blood method.

The sample should be mixed with anticoagulant rapidly to prevent clotting occurring within the tube.

There is a video of this procedure available on the The best method for blood collection is to draw up the required volume of citrate for the desired amount of blood directly into a syringe.

Vacutainers can be used but these sometimes underfill.

This means that if the needle comes out of the vein during sample collection, you need to start from scratch (new needle, new collection tube) Under- or overfilling of the citrate tube will affect coagulation test results (particularly underfilling, which prolongs times of clotting assays).

This maintains the correct blood:citrate ratio which is essential for testing.

5 ml citrate vacutainers contain 0.5 ml of citrate and draw 4.5 ml of blood).

This is nine parts blood to one part citrate (i.e.

For citrate, collect the appropriate volume of blood: This is essential!!.

Citrate (3.2 or 3.8%): All other hemostatic tests. The remaining guidelines apply to citrate tubes.Anticoagulant: Collect blood into the following anticoagulants:.This means that large peripheral veins are optimal sites for obtaining coagulation samples (to ensure rapid blood flow) and if the vein is not entered on the first attempt, a fresh needle should be used. Clean venipuncture is essential: If venipuncture is difficult or blood flow ceases in the middle of collection, a new blood draw will be required. Poor venipuncture will result in activation of coagulation due to contamination with tissue factor.View other sample collection pages specific for hematology, chemistry, urinalysis and cytology. Many causes of prolonged clotting times or decreased factor concentrations are artifactual, due to poor sample collection and handling. Unlike many other clinical pathologic tests, coagulation assays are unforgiving with respect to poor sample collection and handling. The most important aspect of diagnosis of hemostatic disorders is the collection and submission of an optimal sample for testing.

Coolpack catheters