NHA Phlebotomy Certification Practice Exam

Which of the following finger pairings presents an increased risk of bone puncture?

1. Thumb and calluses

2. Index finger and increased nerve endings

3. Third finger and increased possibility of bone puncture

4. Fifth finger and decreased tissue mass

The correct answer is: Third finger and increased possibility of bone puncture

The correct answer highlights the specific anatomy of the fingers and the associated risks during the process of capillary puncture. The third finger, also known as the middle finger, has thicker tissues that can pose a greater risk of penetrating too deeply during a puncture. This is particularly relevant in the context of bone puncture, as it involves reaching beyond the superficial layers of skin and tissue during the procedure. The anatomy of the third finger also compromises potential barriers between the skin and underlying bone. It could house more compact structures than fingers with a thinner tissue layer. An understanding of finger anatomy and the techniques used in phlebotomy plays a critical role in minimizing complications such as bone puncture. While the other choices introduce various factors, they do not specifically pertain to the risk of puncturing bone during a capillary puncture. For example, the thumb and calluses may indicate hardened tissue but do not inherently increase the risk of bone injury. The index finger's increased nerve endings pertains to sensitivity but does not necessarily correlate to a higher chance of bone puncture. Similarly, the fifth finger tends to have decreased tissue mass, which suggests a lower risk of penetrating deeply enough to reach the bone. Thus, the third finger stands out as particularly relevant to