What amount of fluid should be discarded from a central venous catheter prior to drawing blood?

Prior to drawing blood from a central venous catheter (CVC), discarding a specific amount of fluid is essential to prevent contamination of the blood sample and ensure accuracy in laboratory results. The recommended amount to discard is typically 2 ml.

This practice helps to clear any residual fluid that may have been an infusion or medication administered through the CVC, ensuring that the blood sample reflects the patient's current state more accurately. By discarding this volume, the risk of obtaining a sample that contains contaminants from previous infusions is minimized, which is crucial for accurate diagnostic purposes.

In clinical settings, discarding this specific volume before drawing blood is a standard practice endorsed by various healthcare guidelines to uphold the integrity of blood samples. This protocol also helps in minimizing the chances of drawing a hemolysed sample, which can occur if the sample is taken from a line that has recently received intravenous therapy.