How should a light blue tube be filled for accurate test results?

The correct approach for filling a light blue tube is to ensure that it reaches the indicated fill line, which is crucial for maintaining the appropriate blood to anticoagulant ratio of 9:1. This ratio is essential because light blue tubes contain sodium citrate, which is an anticoagulant used for coagulation studies. If the tube is not filled properly, it can lead to inaccurate test results.

When the blood volume is too low, there is an excess of anticoagulant relative to the blood sample, which can dilute the sample and potentially affect coagulation parameters. Conversely, overfilling the tube can lead to insufficient anticoagulant and compromised test results as well. Therefore, adhering to the specified fill line ensures the integrity of the test and accurate results for assays such as PT (prothrombin time) and aPTT (activated partial thromboplastin time).

In summary, filling to the indicated line maintains the necessary balance between blood and anticoagulant, thereby producing reliable laboratory results.