Which type of blood is characterized by its dark coloration during venipuncture?

Deoxygenated blood is characterized by its dark coloration when observed during venipuncture. This color variation occurs because deoxygenated blood, which returns to the heart from the body’s tissues, has a higher concentration of carbon dioxide and lower levels of oxygen. This process gives the blood a darker red hue compared to oxygenated blood, which is bright red due to the presence of oxygen that binds to hemoglobin in red blood cells.

The other blood types listed do not exhibit the same dark coloration. Oxygenated blood appears bright red, reflecting its high oxygen levels. Arterial blood, which is also oxygen-rich, shares this bright red characteristic. Capillary blood, found in small vessels and often used in fingersticks, can vary in color depending on its oxygenation level, but generally, it mimics the color of venous or arterial blood based on recent activity and location. Thus, the distinct dark coloration is a clear identifier of deoxygenated blood during venipuncture.