Patients with bruising after a blood draw should not be overly concerned. A small amount of blood flowing into the blood vessels after a blood draw can lead to subcutaneous bruising. The bruising can also be caused by not applying proper pressure to the blood collection site after the blood draw or by applying too little pressure for too long, so the nurse will explain to the patient after the blood draw to press the blood draw wound with a cotton swab to avoid excessive blood flow. The duration of pressure is 1-3 minutes. A small amount of bruising can also be left untreated and can disappear on its own; if the area is large, cold compresses can be applied within 24 hours and then hot compresses after 24 hours to facilitate rapid absorption and disappearance of the bruising. Bruising after blood draw will not occur in most patients. In some patients with poor special coagulation function, the time required for pressure after blood draw is longer, maybe even 5-10 minutes to avoid subcutaneous bleeding; for most patients to come after blood draw, 1-2 minutes of pressure is sufficient.