The largest manufacturer of blood collection kits in the country readily admits that the failure to invert the tubes eight to ten times may result in microclotting of the blood, which is invisible to the naked eye. This, in turn, leads to false results...according to the manufacturer. Microclotting occurs because the anti-coagulant, potassium oxalate, does not completely mix with the blood unless the tubes are inverted the required number of times.
Another Collection Issue
From time to time we encounter a situation where a nurse has used a butterfly needle. These needles can cause the blood cells to be virtually destroyed and also result in falsely elevated results because the needle is too small for the vaccum pressure and causes cellular breakdown (hemolysis) of the red blood cells. The tubing does not have any anti-coagulant or preservative, so the air in the tubing initiates clotting immediately upon contact with the blood flow.