Noninvasive Ultrasound Technique Relieves Uterine Fibroids

ROCHESTER, Minn., Aug. 1 -- Symptomatic uterine fibroids can be durably treated with MRI-guided focused ultrasound, reported investigators here.

Two years after being treated with focused ultrasound surgery for symptomatic leiomyomata, women had durable relief of symptoms as measured by symptom severity scores, reported Elizabeth Stewart, M.D., of the Mayo Clinic, and colleagues.

The more complete the ablation, the better the long-term outcome, the authors reported in the Aug. 1 issue of Obstetrics & Gynecology.

"Up to one-third of women who undergo alternatives to hysterectomy to treat fibroids experience recurrence of fibroids, so demonstrating the durability of focused ultrasound is important," Dr. Stewart said. "Our study does this by examining rates of subsequent surgery for fibroid tumor symptoms and other key outcomes such as uterine shrinkage."

The authors reviewed data on 359 women who completed two years of follow-up in all clinical trials of MRI-guided focused ultrasound surgery for uterine leiomyomata.

The non-invasive technique involves ultrasound delivered to target tissues under magnetic-resonance guidance, via an external transducer that delivers energy through the abdominal wall. The focused energy creates a thermal coagulation necrosis of targeted leiomyomata. Real time monitoring of the beam path is required to ensure that tissues proximal and distal to the targeted lesions are not harmed, the authors noted.

Study outcomes included quality-of-life measures as assessed by the symptom severity score of the Uterine Fibroid Symptoms Quality of Life Questionnaire, and clinical measures, including uterine shrinkage, the need for additional leiomyoma treatment, and time to additional treatment.

The authors determined how completely the ablation was achieved by determining the non-perfused volume ratio after treatment, which they calculated from post-treatment gadolinium-enhanced MRI, and by assessing the extent of tissue necrosis.

They found that women undergoing the procedure had a significant improvement in symptom severity scores compared with baseline. The range of mean scores at study outset was 60.6 + 12.3 to 65.8 + 18.5 points.

At the study's end, the mean score for women with a non-perfused volume ratio of 20% or less was approximately 40, and the mean score for women with volume ratios greater than 20% was about 35, according to data reported as a graph.

The degree of improvement was significantly greater among women with more complete ablation (P<0.001), and a survival analysis showed that women in the high nonperfused volume group had a significantly greater reduction in the percentage of those who required additional leiomyoma treatment (P=0.001).

In addition, the mean shrinkage and mean residual nonperfused volume ratio were both significantly above zero at six months in the high non-perfused volume group (P<0.001).

"The incidence of adverse events is low," the authors noted. "However, for women with minimal treatment, the risk of additional procedures is high."

They acknowledged that their study was limited by the lack of an untreated control group and by a lack of evidenced-based information about the natural history of leiomyoma symptoms and treatment outcomes.