Which statement is true about capillary collection in relation to venipuncture?

• A. Capillary blood is identical to venous blood in composition.
• B. Capillary puncture is only used for arterial samples.
• C. Capillary puncture is used when venipuncture is not advised.
• D. Capillary puncture cannot be performed on infants.

Answer: (C)

Capillary collection is chosen when venipuncture isn’t advised or feasible because it provides a less invasive, quicker way to obtain a small blood sample, which is especially helpful when veins are difficult to access, when the patient is young or uncooperative, or when only a tiny volume is needed. Capillary blood isn’t identical to venous blood; it’s a mixture that includes some interstitial fluid, so levels of certain analytes can differ from those in venous blood, which is why some tests are more suitable for venipuncture. It’s also not used for arterial samples, which require arterial puncture. Capillary sampling is routinely performed on infants (for newborn screening) because it minimizes distress and risk while providing the needed small-volume blood. This context makes the statement true: capillary puncture is used when venipuncture is not advised.