Preoperative preparations for myelocentesis: preparation of supplies: 1 set of conventional sterilized treatment tray; 1 sterile myelocentesis kit (containing 1 curved tray, 1 350px hemostasis clamp, 1 myelocentesis needle, 1 towel, 3 gauze balls, 2 pieces of gauze, etc.); other supplies (1 sterile 5ml syringe, 1 20ml syringe, 1 packet of sterilized cotton swabs, 2% lidocaine, 2 sets of sterile gloves, several slides and push slides, culture medium, alcohol lamp, etc.). (1 sterile 5 ml syringe, 1 20 ml syringe, 1 packet of sterilized cotton swabs, 2% lidocaine, 2 pairs of sterile gloves, several slides and slide pusher, culture medium, alcohol lamp, etc.) Patient preparation Explain to the patient the purpose of the puncture and the precautions to be taken, and briefly explain the puncture procedure in order to allay the patient's concerns and obtain his/her cooperation. Inform the patient that bone marrow aspiration is a small invasive procedure, which is performed under local anesthesia for a few minutes; that the total amount of bone marrow in a normal human body is about 2,600 g, and only 0.2 g of bone marrow is aspirated, which is less than 1/10,000% of the total, and does not affect health; that there is a slight pain at the site of the bone marrow aspiration, which is normal, and that the patient will recover soon; and that the patient should maintain the same body position during the procedure. The position should remain unchanged during the procedure. Ancillary investigations and drug allergy tests Preoperative platelet, bleeding time and coagulation time tests should be performed. Know whether the patient has a history of allergy to relevant anesthetic drugs, if necessary, do drug sensitivity test or change to other anesthetic drugs to avoid accidents.