Question 39

Hemoconcentration of a venous blood sample is most often caused when the tourniquet is in place for more than 2 minutes.

Hemoconcentration occurs when the tourniquet is applied for an extended period, typically over 2 minutes, leading to an increased concentration of cells and proteins in the blood sample.

A) the site is prepped with povidone iodine.

This option is incorrect as the use of povidone iodine for skin preparation does not contribute to hemoconcentration. It is primarily used for antiseptic purposes to reduce the risk of infection during blood collection.

B) the tourniquet is in place for more than 2 min.

This is the correct answer because prolonged application of a tourniquet restricts blood flow, resulting in an increased concentration of cells and solutes in the blood sample, which is the definition of hemoconcentration.

C) the specimen is not refrigerated within 30 min.

This option is incorrect since failing to refrigerate a blood specimen affects its stability and can lead to degradation of certain components, but it does not cause hemoconcentration itself.

D) the needle is removed before the tourniquet.

This option is also incorrect. Removing the needle before releasing the tourniquet may lead to blood leakage or hematoma formation, but it does not cause hemoconcentration, which is specifically related to prolonged tourniquet application.

Conclusion

In summary, the correct answer is option B, as it directly addresses the condition leading to hemoconcentration through prolonged tourniquet use. The other options either relate to different aspects of blood sample handling or do not contribute to hemoconcentration, reinforcing that option B is the only viable cause in this context.