Transvaginal ultrasound therapy for symptomatic uterine leiomyomas

The primary endpoint for the Korean study in the European Journal of Obstetrics, Gynecology, and Reproductive Biologywasthe nonperfused volume (NPV) ratio measured immediately after therapy.¹

Among the 13 women who underwent vHIFU therapy for 33 uterine leiomyomas, NPV ratios were 0.76, while the lower limit of a one-sided 97.5% confidence interval was 0.67, surpassing the non-inferiority cut off of 0.50.

Principal investigator Kidong Kim, MD, a professor of ob/gyn at Seoul National University Bundang Hospital in Seongnam-si, Gyeonggi-do, Republic of Korea, participated in a trial several years ago that examined the efficacy and safety of transabdominal HIFU therapy using a new ultrasound-guided HIFU system, the Alpius 900, in women with leiomyoma.

“That was my first exposure to HIFU therapy,” Kim told Contemporary OB/GYN. “Because gynecologists already use transvaginal ultrasound to diagnose leiomyoma instead of transabdominal ultrasound, I believed vHIFU therapy might be useful in treating leiomyoma as well.”

The two-center study was conducted at Seoul National University Bundang Hospital and Seoul National University Hospital from December 2017 to February 2019. Premenopausal women with symptomatic, contrast-enhanced uterine leiomyomas with a diameter ≤5 cm were eligible.

Under sedation or monitored anesthesia, leiomyomas were ablated with vHIFU via ultrasound guidance.

“In the early development period, our team was unsure whether transvaginal HIFU therapy was possible because there were so many obstacles, including probe size limitation, power limitation, cooling and a probe that could endure heat,” Kim said.

Secondary endpoints were changes in Uterine Fibroid Symptom-Quality of Life (UFS-QOL) scores, dysmenorrhea visual analog scale (VAS), uterine leiomyoma volume, rate of subsequent therapy and treatment-emergent adverse events (TEAE).

At 3-month follow-up, the median UFS-QOL symptom severity score significantly improved from 66.60 at baseline to 32.85 (P = 0.0010) and the median health-related quality of life score from 41.40 to 73.30 (P = 0.0010).

Dysmenorrhea VAS also significantly improved at 3 months, from a mean of 50.92 at baseline to 20.67 (P = 0.0019).

In addition, volume of uterine leiomyoma was significantly reduced during the same time period, from a mean of 8.10 cm3 to 5.30 cm3 (P < 0.0001), and no patient received subsequent therapy.

“Nonperfusion volume ratio and symptom scores were compatible to those of transabdominal HIFU therapy,” Kim said.

A total of eight study participants incurred 26 TEAEs, all of which were resolved without sequelae.

“We were relieved that vHIFU produced minimal side effects,” Kim said. “We thought that bowel injury could occur.”

A downside of the technology, however, is that cases of large myomas and myomas locating distantly from the vagina are not suitable for vHIFU.

Despite the efficacy of HIFU in women with small myomas (<= 5cm), “the power of the vaginal probe is limited because the size of the vaginal probe is restricted by the diameter of the vaginal canal,” Kim said. “But with advancements in the technology, I think the target population of vHIFU will increase.”

Similar to transabdominal HIFU, concomitant medications such as methergine or oxytocine could augment the efficacy of vHIFU, according to Kim. And to enhance safety, “margin saving in subserosal leiomyoma and not treating too closely to the bowel are necessary,” he said.

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Kim reports no relevant financial disclosures.

Reference

1. Lee JY, Kim K, Hwang SI, et al.Efficacy and safety of transvaginal high-intensity focused ultrasound therapy in women with symptomatic uterine leiomyomas: a clinical trial. Eur J Obstet Gynecol Reprod Biol. Published online November 17, 2020. doi:10.1016/j.ejogrb.2020.11.049