Certified Medical Assistant (CMA AAMA)Procedures, Examinations and DiagnosticsMedium
A medical assistant performs a finger stick to obtain a capillary sample for a point-of-care glucose test. What should the medical assistant do immediately after puncturing the skin and before collecting the sample?
- AImmediately touch the test strip to the puncture site
- BApply a tourniquet to increase blood flow to the site
- CWipe away the first drop of blood with clean gauze
- DSqueeze the finger firmly to force out a large drop of blood
Show answer & explanationAnswer & explanation
Correct answer: C. Wipe away the first drop of blood with clean gauze
The first drop of blood is wiped away because it may contain tissue fluid or alcohol residue that can dilute the sample and cause inaccurate glucose readings. Subsequent drops are used for testing.
Why the other options are wrong
- A. Touching the first drop directly risks inaccurate results due to contamination.
- B. Tourniquets are not used for capillary punctures.
- D. Excessive squeezing causes hemolysis and tissue fluid contamination, affecting accuracy.
First Drop Discard in Capillary Testing
The first drop of blood from a capillary puncture is wiped away before sample collection to prevent contamination from tissue fluid or antiseptic residue.
- First drop may contain interstitial fluid
- Wiping prevents diluted/inaccurate results
- Applies to glucose and other POC capillary tests
Memory trick: First drop's a dud—wipe it, then collect the good stuff.