Why should heparin be avoided when collecting blood for a differential count?

Heparin is an anticoagulant commonly used in blood collection, but it can interfere with certain laboratory tests, particularly a differential white blood cell count. When heparin is used, it may alter the morphology of white blood cells, which can lead to inaccurate interpretations of the differential count. Morphological changes can include alterations in cell shape or structure, making it challenging for clinicians to assess the types and proportions of white blood cells accurately. This distortion directly impacts the reliability of the differential count, which is critical for diagnosing various health conditions. Therefore, avoiding heparin during blood collection for a differential count is essential to ensure the integrity of the test results.