I. Preoperative preparation. 1.Patient routine examination: blood routine, clotting time, infectious diseases, etc. 2, instrument preparation: one McMurdo machine (McMurdo EX handle, one puncture needle, 2 vacuum barrels), one high frequency ultrasound (probe going to 7.5MHz, 125px), surgical kit preparation (straight forceps, curved forceps, sharp blade, gauze, scissors, lumpectomy set, curved tray, medicine cup, cavity towel), medicine preparation (saline, epinephrine, 2% lidocaine, iodophor), 5ml syringe, 9 size long needle, drainage strip, specimen bag, pathology request form, cotton pad, bandage, sterile gloves, sterile paraffin oil (or sterile coupling agent), 2 lumpectomy sets. Second, body position. The patient is placed in a supine position, or laterally if necessary, with the affected arm abducted to expose the surgical field. Third, the surgical steps. 1.Localization of the lesion. Ultrasound guidance is very important, and the location and number of masses should be marked with a marker before surgery. First detect the breast lesion, and also use ultrasound-assisted localization for the palpable lesion to determine the site, size, shape, and number of the mass, and mark it with a marker. Determine the location of the incision. In multiple mass excision, the puncture sites must be integrated to take into account all lesions. Routine disinfection with iodophor and sterile towels are laid. 2 .Anesthesia. Under ultrasound guidance, local anesthetic (2% lidocaine 50 mL + % procaine 10 mL) is injected sequentially at the expected incision location, puncture needle tract, and around the lesion, respectively. A small amount of epinephrine is added to the anesthesia (use with caution in hypertensive individuals) to prolong the duration of anesthetic action and reduce bleeding in the operative area and needle tract. Local anesthetic drugs are accurately injected around the target lesion or the gap between the breast and the pectoralis major muscle, which can keep the local pain to a minimum and receive a better anesthetic effect. 3.Surgical procedure. (1) Puncture positioning: At the pre-puncture point, the skin is cut with a sharp knife 2-3 mm, the puncture needle is inserted, and the puncture needle is “extended” to the base of the mass through the “subcutaneous tunnel” and pressed against the base of the mass. The maximum diameter of the lesion is detected by ultrasound, which determines the location and direction of the incision (in preparation for a possible second radical open surgery and using the “shortest distance” principle). The insertion of the puncture needle always needs to be parallel to the long axis of the ultrasound probe, or the cross positioning method is chosen. The needle is inserted posteriorly to the lesion under dynamic ultrasound monitoring so that the cutter slot is immediately adjacent to the mass and should be readjusted if the position is poor. For deep breast masses, puncture into the chest wall should be avoided by picking up at the anterior lower edge of the lesion and puncturing as horizontally as possible. (2) Perform spinotomy: Under the guidance of ultrasound, adjust the position of the knife slot and the target lesion so that the target lesion is finally clasped in the knife slot and start spinotomy. When cutting hard lesions, because of their hard texture, the tumor often moves during cutting, so the suction of the puncture needle should be increased and the lesion under the probe should be fixed vertically by holding the ultrasound probe with the left hand. (3) Repeat the rotary cut, and finally stop the rotary cut and remove the needle. Align the notch of the puncture needle with the mass: for larger masses make fan-shaped, rotational, multi-directional dissection at the base of the tumor gradually, so that the cutting plane is gradually moved up from the bottom; and carefully distinguish the difference between the cut specimen and the normal gland. The specimen is carefully distinguished from the normal gland. Multiple rotations and aspirations are performed until the ultrasound image shows no residual lesions and the edges of the specimen are observed to confirm the resection of the lesions, then the rotations are terminated. To a certain extent, the depth of the blade and the direction of the blade need to be adjusted according to the residual mass. Care should be taken not to penetrate the skin when adjusting the position of the puncture needle and the knife slot. During the rotary incision process, the internal blood can be removed by vacuum suction, and finally, after confirming that there is no active bleeding, the puncture needle can be closed completely by pressing the “forward button” under Positions, and then the puncture needle can be withdrawn from the gland. Vacuum suction can be used to remove the local blood accumulation during the rotary incision and before removing the puncture needle. (4) Wound treatment. Compression hemostasis 15 minutes after putting cotton pads, and then with an elastic bandage pressure bandage 24-48 hours (or can use small curved forceps will be Johnson fiber quick that yarn gently sent into the residual cavity, play the role of hemostasis, and then with an elastic bandage pressure bandage 24-48 hours, this method is not as a routine treatment). IV. Precautions. 1, McMurdo surgery is used for the treatment of benign breast lesions, and it is very important to determine the benignity and malignancy of each preoperative examination. 2. Before excision of multiple masses, a clear imaging diagnosis must be made, and the tumors confirmed to be benign should be excised first, and then biopsies should be performed on the masses that may be malignant. The ipsilateral masses should be excised in quadrants and marked well. 3.For patients with breast cancer confirmed by clinical physical examination, ultrasound and mammography, patients with locally advanced breast cancer at the time of biopsy with McMerton can not only obtain a clear diagnosis, but also provide sufficient pathological tissues to detect ER, PR and multiple tumor markers. For biopsy of suspected malignant tumor, the puncture site should be as close as possible to the mass (the distance between the needle incision and the mass is less than 50px) so that the puncture site and the needle tract can be removed together during further surgery, which is called the “shortest distance” principle. If bilateral mastectomy is performed, in principle, two puncture needles are used for rotary excision.