If you cannot find the vein in the inside of the elbow in either arm, look for another one.  Move down the forearm looking for the basilic vein or cephalic vein. These veins may also be visible through the skin. Have the patient lower their arm and make a fist to make the veins more obvious. The cephalic vein runs along the radial side of the forearm. The basilic vein runs along the ulnar side. The basilic vein is less frequently used than the cephalic. It is more likely to roll away from the needle than the cephalic vein because it is not held as tightly in place by the tissues around it. If no veins can be accessed, find the metacarpal veins on the back of the hands. They are usually very visible and can be palpated. They should not be used for elderly patients because the skin is not as supple and does not support the veins as well. In addition, the veins themselves become more fragile. Do not draw blood from areas that:  Are near an infection Have scarring Have a healed burn Are on an arm that is on the same side as where the patient had a mastectomy or fistula placed Are bruised Are above an IV line Are on an arm where the patient has a cannula, fistula, or vascular graft Occasionally, you may encounter problems with the needle, such as going too far into the tissues or inserting it at too low of an angle (so the bevel is against the wall of the vein and impedes blood flow).  Pull the needle back a little bit without removing it from the skin. Change the angle of the needle while it is still under the skin so that it can be inserted into the vein. Protocol in many laboratories dictates that phlebotomists must attempt a venipuncture two times, and to have another person do it if both attempts are unsuccessful.
إذا لم يكن الوريد المرفقي الناصف ظاهرًا، فابحث عن وريد غيره. اعلم بالأماكن التي ينبغي تفاديها. صحح وضع الإبرة الخاطئ. توقف عن التجربة بعد المحاولة الثانية واستدع زميلًا لك ذا خبرة ليسحب هو العينة.