Which anticoagulant is used when blood is sent for blood culture ?
**Core Concept**
The question is testing the understanding of anticoagulants used in laboratory settings, specifically for blood culture. Blood culture is a diagnostic test used to identify the presence of pathogens in the blood, and the anticoagulant used should not interfere with the growth of microorganisms.
**Why the Correct Answer is Right**
The correct answer is EDTA (Ethylenediaminetetraacetic acid), which is a chelating agent that prevents blood clotting by binding to calcium ions. In blood culture, EDTA is used because it does not inhibit the growth of microorganisms and allows for the accurate identification of pathogens. EDTA works by chelating calcium ions, which are essential for the coagulation cascade. This prevents the formation of blood clots and allows the blood sample to remain liquid, making it ideal for blood culture.
**Why Each Wrong Option is Incorrect**
**Option A:** Heparin is a strong anticoagulant that works by activating antithrombin III, which inhibits thrombin and factor Xa. Heparin is not suitable for blood culture because it can inhibit the growth of microorganisms.
**Option B:** Citrate is another anticoagulant that works by binding to calcium ions, but it is not the preferred choice for blood culture. Citrate can inhibit the growth of some microorganisms, especially those that require calcium for growth.
**Option C:** Oxalate is a strong anticoagulant that can inhibit the growth of microorganisms, making it unsuitable for blood culture.
**Clinical Pearl / High-Yield Fact**
When ordering blood cultures, it is essential to use the correct anticoagulant to ensure accurate results. EDTA is the preferred anticoagulant for blood culture because it does not inhibit the growth of microorganisms.
**Correct Answer:** C. EDTA (Ethylenediaminetetraacetic acid)