Certified Medical Assistant (CMA AAMA)Procedures, Examinations and DiagnosticsEasy
A medical assistant is performing a capillary puncture on an adult patient to obtain blood for a point-of-care test. Which site is appropriate for the puncture?
- AThe dorsal surface of the hand between the knuckles
- BThe center of the fingertip pad directly over the fingerprint whorl
- CThe palmar surface of the wrist
- DThe lateral or medial area of the palmar surface of the third or fourth fingertip
Show answer & explanationAnswer & explanation
Correct answer: D. The lateral or medial area of the palmar surface of the third or fourth fingertip
The lateral or medial palmar surface of the third or fourth finger is preferred because it has fewer nerve endings and adequate blood flow, minimizing pain and injury risk. The center of the fingertip should be avoided due to increased nerve density.
Why the other options are wrong
- A. The dorsal hand lacks sufficient capillary blood supply for reliable sampling.
- B. The center of the fingertip has more nerve endings and is more painful.
- C. The wrist is not an approved capillary puncture site due to risk of injury to underlying structures.
Adult Capillary Puncture Site
The preferred site for adult finger sticks is the lateral or medial palmar surface of the third or fourth finger.
- Avoid center of fingertip (more nerves)
- Avoid thumb, pinky, and dorsal hand
- Site chosen to minimize pain and maximize blood flow
Memory trick: Stick the side, not the center, to keep the pain down.