Final answer:
When taking a sample for a coagulation test from a three-year-old patient, it is important to use a method that is safe and comfortable for the patient while still ensuring the integrity of the sample for accurate testing.
Step-by-step explanation:
When taking a sample for a coagulation test from a three-year-old patient, it is important to use a method that is suitable for their age and size. This usually involves using a smaller needle, such as a butterfly needle, and collecting a smaller volume of blood. The sample can be collected from a vein in the arm or from a fingerstick.
Blood collection tubes containing an anticoagulant, such as EDTA or heparin, should be used to prevent clotting of the sample. The tube should be filled to about one third full, as specified in the instructions.
Overall, it is important to use a method that is safe and comfortable for the three-year-old patient while still ensuring the integrity of the sample for accurate coagulation testing.