To prevent hemoconcentration during venipuncture, the phlebotomist should ask the patient to release his or her fist when blood begins to flow: fist-pumping may increase blood potassium levels and should not be encouraged. Excessively massaging the site or probing or redirecting the needle multiple times may result in hemoconcentration.

If a patient is markedly obese, the first site to check is the antecubital area because patients often exhibit a double crease in that area. and the median cubital vein can often be easily palpated and accessed within that creased space. If the phlebotomist is unable to locate the median cubital vein, the cephalic vein may sometimes be accessed if the arm is rotated medially. The phlebotomist may also ask the patient where blood draws have been successful previously.

If a patient complains of nausea after a blood draw, the most appropriate response is to give the patient an emesis basin (because nausea often leads to vomiting) and encourage deep breathing because this sometimes eases nausea. A cool, damp cloth may also be applied to the patient's forehead. In most cases, nausea subsides within a few moments, but first-aid personnel should be notified. If the patient is lying flat and supine, he or she should be turned to one side to avoid aspiration if vomiting occurs.

Hematocrit (Hct), also called packed cell volume (PCV), measures the volume of RBCs in a patient's blood. A small sample of anticoagulated blood is centrifuged; the results reflect the percentage of cells to liquid. The normal hematocrit value varies according to gender and age:

The correct method of removing a stopper from a specimen tube is to pull it straight up and away from the tube. If possible, a removal device or robotics should be used to minimize human contact. Any fluid in eontact with the stopper may become aerosolized when the stopper is removed; therefore, if a tube does not have a built-in safety feature to prevent aerosolization, the stopper should be grasped with a gauze pad or a tissue.