The blood flow is less and slower when the arm draws blood for blood test, which may be related to cold weather, low blood volume and other factors.
1. Cold weather: when the weather is cold, the patient’s blood vessels contract, and when the blood is drawn, the speed of blood flow is slower, and the blood flow is less, at this time, pay attention to the heat preservation or appropriate exercise can be drawn enough blood.
2. Low blood volume: when the patient has a large amount of bleeding or there is a problem of blood viscosity, it will also lead to the above performance. Those who have a large amount of bleeding leading to low blood volume need to be treated actively, and those who have found the blood viscosity need to determine whether there is a problem of dehydration or diarrhea.
It is recommended to consult the doctor for precautions and contraindications before taking the blood test.