What does hemolysis refer to in blood samples?

Hemolysis refers specifically to the breakdown of red blood cells. This process can occur in a variety of situations, both in the body and outside of it, such as during sample collection, processing, or transport. When red blood cells are hemolysed, they rupture and release hemoglobin into the surrounding fluid, which can lead to changes in the blood sample's appearance and composition. Hemolysis can interfere with laboratory tests by causing inaccurate results, particularly in tests that require the measurement of specific substances released from the cells, such as potassium.

The other options focus on different aspects of blood or its components. The formation of blood clots refers to coagulation processes, which is separate from the breakdown of blood cells. An increase of white blood cells pertains to immune responses or infections, distinctly different from hemolysis. The presence of foreign substances introduces a concept of contamination or infection, which is unrelated to the physical breakdown of red blood cells. Thus, the definition of hemolysis is clearly captured in the correct answer, emphasizing the specific process of red blood cell destruction.