In complicated forms of various diseases, for a more accurate diagnosis and identification of the causes of their appearance, blood from a vein in an amount of up to 10 ml may be required. The results of studies depend on how well the blood sampling procedure is performed.
If a laboratory technician can take capillary blood , then blood sampling from a vein should be performed by a qualified nurse in a sterile treatment room using a special tool.
It is important that the patient is prepared for blood donation, as there are a number of factors that can adversely affect the outcome of the study. It is necessary to avoid physical strain before the procedure (brisk walking, running, climbing stairs), refuse to eat before the test, do not smoke or drink alcohol, and maintain emotional calm.
Before taking blood from a vein, the medical staff must provide the patient under examination with a 15-minute rest. Directly during the procedure, the patient should sit, and a seriously ill patient can lie. If the patient ate, smoked or drank alcohol, then the test can be postponed to another date.
It is most convenient to take blood from the veins of the forearm, since here they are located on the surface and are clearly visible. The following veins can be used here: external superficial, ulnar, median superficial, radial, median vein of the elbow, internal superficial.
Veins are differently fixed in the tissues of the body, so blood is best taken from less mobile vessels, as they are more convenient for piercing with a needle. Such blood vessels include the median vein of the elbow and the external superficial.
In the absence of a full-fledged experience, blood sampling should not be carried out from the internal superficial vein, since the worm and artery are located next to it. An inaccurate injection may harm the patient.
If the veins of the elbow bend are not visible enough (for example, in obese people), then it is possible to carry out blood sampling from the venous vessels of the back surface of the hands, as well as the popliteal cavity.
In infants, blood is drawn from veins located on the temples. When the child screams, they swell significantly, which makes it more safe to puncture the needle. Also, blood from a vein can be taken from the heel of a child.
Avoid sampling scars, hematomas, from venous vessels used for transfusion of medical solutions. In patients with diabetes, with a violation of peripheral blood flow, angiopathy, blood from leg veins should not be taken.
The procedure is performed in disposable rubber gloves. Otherwise, gloves should be pre-treated with medical alcohol.
The following tools and accessories are used for blood sampling from a vein: vacutainers (disposable plastic blood sampling systems), disposable syringes and needles with a cross-sectional diameter of 0.55-0.65 mm, an elastic cord, a test tube, sterile rubber gloves, moistened cotton balls alcohol.
Blood sampling from a vein is as follows:
A tourniquet is applied to the middle third of the shoulder to stop blood flow.
The elbow bend is treated sequentially with two balls of cotton wool, previously moistened with alcohol. The patient at this time clenches and unclenches his fist.
The fullest vein is found and fixed by pulling the skin. The patient should clench his hand into a fist.
Firmly holding the tip of the needle with the cut up and parallel to the skin, pierce the vein and carefully, along the vessel, insert the needle a third of the length.
Substitute a tube to the needle cannula and bleed in the right amount.
Remove the harness. The patient should unclench his fist.
The needle is removed, and the puncture site is covered with a cotton alcohol ball.
The patient must bend the arm at the elbow joint to compress the vein until the bleeding stops.
A direction must be attached to the tube containing the blood from the vein.