What substance may dilute the blood if the finger is squeezed too tightly during a skin puncture?

Squeezing the finger too tightly during a skin puncture can force interstitial fluids from the surrounding tissue into the blood sample, which can effectively dilute the obtained blood specimen. This interstitial fluid is referred to as tissue fluid. It contains water, electrolytes, and small amounts of proteins, and its presence in the blood sample can lead to inaccurate laboratory results, particularly if glucose or other analyte levels are being assessed.

When skin is punctured for a blood sample, the aim is to collect a specimen that accurately reflects the blood content in the circulatory system. Overly aggressive squeezing causes a mix of blood and tissue fluid, thus compromising the integrity of the sample. Understanding this impact is crucial in phlebotomy practices to ensure accurate test results and patient care.

In contrast, while serum, plasma, and platelet count are important components of blood, they are not the substances that would dilute the sample when excess pressure is applied during the collection.