Evaluating the safety of high-intensity focused ultrasound treatment for rectal endometriosis: results from a French prospective multicentre study including 60 patients

Abstract

Study question: Is increasing the intensity of high-intensity focused ultrasound (HIFU) by 30% in the treatment of rectal endometriosis a safe procedure?

Summary answer: This study demonstrates the safety of a 30% increase in the intensity of HIFU in the treatment of rectal endometriosis, with no Clavien-Dindo Grade III complications overall, and namely no rectovaginal fistulae.

What is known already: A feasibility study including 20 patients with rectal endometriosis demonstrated, with no severe complications, a significant improvement in digestive disorders, dysmenorrhoea, dyspareunia, and health status, although the volume of the endometriosis nodule did not appear to be reduced.

Study design, size, duration: A prospective multicentre cohort study was conducted between 2020 and 2022 with 60 patients with symptomatic rectal endometriosis. Following the failure of medical treatment, HIFU treatment was offered as an alternative to surgery.

Participants/materials, setting, methods: As the main objective of this study was to examine safety, all adverse events observed during the 6 months of follow-up were analysed and graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE) and Clavien-Dindo classifications. Secondary objectives included evaluating the evolution of symptoms using validated questionnaires: gynaecological and digestive pain symptoms with a visual analogue scale, health status with the Medical Outcomes Study 36-item Short Form (SF-36) questionnaire, average post-operative daily pain level, and analgesic medication required in the 10 days following treatment. MRI was also performed at Day 1 to detect early complications. Finally, we performed a blinded MRI review of the evolution of the nodule at 6 months post-treatment.

Main results and the role of chance: The procedure was performed under spinal anaesthesia for 30% of the patients. The median duration of treatment was 32 min. Fifty-five patients left the hospital on Day 1. MRI scans performed on Day 1 did not highlight any early-onset post-operative complication. Using the Clavien-Dindo classification, we listed 56.7% Grade I events, 3.4% Grade II events, and no events Grade III or higher. At 1, 3, and 6 months, all gynaecologic, digestive and general symptoms, as well as health status, had significantly improved. The evolution of the nodule was also significant (P < 0.001) with a 28% decrease in volume.

Limitations, reasons for caution: The main objective was safety and not effectiveness. The study was not randomized and there was no control group.

Wider implications of the findings: HIFU treatment for rectal endometriosis results in an improvement of symptoms with low morbidity; as such, for selected patients, it could be a valuable alternative to surgical approaches following the failure of medical treatment.

Study funding/competing interest(s): The study was funded by the company EDAP TMS. Professors Dubernard and Rousset are consultants for EDAP TMS. Dubernard received travel support from EDAP-TMS. Dr F. Chavrier received industrial grants from EDAP-TMS. He has developed a device for generating focused ultrasonic waves with reduced treatment time. This device has been patented by EDAP-TMS. Dr Lafon received industrial grants from EDAP-TMS; he declares that EDAP-TMS provided funding directly to INSERM to support a young researcher chair in therapeutic ultrasound, which is unrelated to the current study.

Trial registration number: ClinicalTrials.gov identifier NCT04494568.

Keywords: Medical Outcomes Study 36-item Short Form; deep infiltrating endometriosis; gastrointestinal symptoms; gynaecological symptoms; health status; high-intensity focused ultrasound; rectal endometriosis; safety.

Figure 1.

High-intensity focused ultrasound energy plan on a transversal slice; image obtained during treatment for rectal endometriosis. Balloon around the probe. RM, rectal mucosae; RN, rectal nodule developed from the right uterosacral ligament; EL, limits of endometrial nodule, defined manually by the clinician. The number of HIFU beams required to treat the area is based directly on this contouring. TD, limits of the thermal diffusion depending on number of HIFU beams (yellow line); Hb, HIFU beams; HIFU, high-intensity focused ultrasound.

Figure 2.

Evolution of symptoms and health status at 1, 3, and 6 months after treatment by high-intensity focused ultrasound for rectal endometriosis. (A) Symptoms, measured by visual analogue scale (1–10); (B) health status, measured by Medical Outcomes Study 36-item Short Form questionnaire. Pre-op, pre-operative; 1-mo, 1 month; 3-mo, 3 months; 6-mo, 6 months.

Figure 3.

Blinded revue of the nodule evolution at 6 months post-treatment (N = 57). *P<0.05. HIFU: high-intensity focused ultrasound.

Figure 4.

MRI T2 sagittal sequences performed on the same level. (A) Before treatment, (B) Day 1 after treatment, and (C) 6 months post-treatment. The rectal endometriosis nodule is indicated by the white arrow. In panel (B), the hyperintensity shows a thicker nodule and oedema corresponding to the effect of the high-intensity focused ultrasound treatment. Panel (C) shows that the nodule is no longer visible.