Which two types of blood specimens are commonly collected?

The selection of venous blood and capillary blood as the commonly collected blood specimens is grounded in the clinical context and the practicalities of blood collection.

Venous blood is often preferred for a wide range of laboratory tests, including complete blood counts, metabolic panels, and coagulation studies. The collection process involves the insertion of a needle into a vein, typically in the arm, which allows for larger volumes of blood to be drawn and provides a more stable matrix for many tests.

Capillary blood collection, on the other hand, is typically performed through a fingerstick or heelstick, particularly in infants. This method is advantageous for smaller volumes required in point-of-care testing or when venous access is challenging. Because capillary blood reflects the composition of arterial blood, it is very useful for certain tests, especially in pediatric cases.

While arterial blood collection is critical in specific circumstances such as assessing blood gas levels, it is less frequent compared to venous and capillary blood collection, making that choice not as commonly associated with routine specimen collection.

Other options such as sera, plasma, and whole blood pertain more to the components of blood rather than the methods of collection. For instance, serum and plasma are derived from blood after certain processing steps,