US-guided MWA should not be performed during the menstrual or ovulatory period.

Patients adopt a supine position. Ablation is performed under intravenous conscious sedation using sodium propofol. Although intestinal tract preparation is done before therapy, a percutaneous approach could have the risk of inadvertently puncturing the bowel in some patients. Pushing the abdominal wall little by little, using a pressed probe before percutaneous puncture, keeps the intestinal tract away from the antenna. Of note is that the shapes of coagulation necrosis are spheroid but not a rigorous sphere. Thus, the needle tip is not inserted into the center of the endometrial-myometrial area, but close to the far end (Fig. 23.1a). Although the border may be poorly defined, the presence of subendometrial linear striations, subendometrial echogenic nodules, asymmetric myometrial thickness, and inhomogeneous hypoechoic areas can be used to identify the margin of nidus in the myometrium [17]. Besides, MRI can also help to recognize the lesion. When the endometrial-myometrial area is less than 3 cm, one antenna is enough, while if it is larger than 3 cm, two antennas are suitable. 50–60 W is the commonly used power in the treatment. The whole procedure is under ultrasonogram monitoring [18]. The antenna could be repositioned until the hyperechogenic signal reaches 3–5 mm from the serosa (Fig. 23.1b) and CEUS shows the non-perfused area reached at least 50 % of the endometrial-myometrial area (Fig. 23.1d). However, once the hyperechogenic signal is found in the uterine cavity, the ablation should be stopped immediately to avoid endometrium impairment.

All vital signs need to be monitored during the whole procedure. The color of urine and gauze balls also should be observed to monitor the bleeding timely.

Patients’ temperature, hemorrhage, abdominal pain, and routine blood, urine, and stool tests should be paid close attention to after ablation. From these results, the doctor should judge whether infection and surrounding organ injury have occurred.

Post-ablation ce-MRI is performed within 3 days to evaluate both the possible injury to the surrounding organs accurately and the range of the non-perfused area [19] (Fig. 23.1f). Figures 23.1, 23.2, and 23.3 show the changes of different types of adenomyosis after MWA.

Uterine volumes, hemoglobin, CA125, the questionnaire Uterine Fibroid Symptom and Quality of Life, and dysmenorrhea levels could be used to evaluate effectiveness. Also, serum gonadal hormonal changes and possible complications related to MWA should also be recorded.

According to the reported references, our department has performed the largest number of cases in adenomyosis ablation, so the therapeutic efficacy and experiences of our department will be introduced to make a reference (Table 23.1).

Uterine enlargement, menorrhagia, and dysmenorrhea are the three most common clinical presentations of adenomyosis. Thus, the decrease of uterine volume and dysmenorrhea level as well as the increase of hemoglobin (hb) can conclude the treatment is effective directly. In our latest perspective study, we performed MWA in 145 patients with a median age of 39.38 years, average uterine size was 278.76 cm³. Most of them show notable improvements after ablation. The size of uterus at 3, 6, 12, and 18 months’ follow-up indicates a decrease of 46.75, 46.88, 44.53, and 32.84 %, respectively, when compared with baseline. And the 3 months’ reduction rate reached 46.75 %, which is much more than UAE and HIFU in literatures [20–22]. These may be because MWA has a relative high thermal efficiency.