Thesis defense: « Description, evaluation and improvement of a new technique for the management of rectosigmoid deep invasive endometriosis using transrectal ultrasound-guided high intensity focused ultrasound (HIFU) »

Author: Charles-André PHILIP- Praticien Hospitalier
Service de Gynécologie-Obstetrique
CHU Lyon Croix-Rousse, 69004 LYON
Location: Conference Room - LAbTAU INSERM 1032- 151 Crs Albert Thomas 69003 Lyon;
Summary: 

OBJECTIVES: In this thesis, we describe a new technique for the management of rectosigmoid endometriosis by transrectal ultrasound-guided high intensity focused ultrasound ultrasound (TR-USgHIFU). We also review several limiting factors of this technique before assessing several modifications to improve the feasibility and the efficacy of the procedure.

METHODS: We first conducted a phase I clinical trial to test the feasibility of TR-USgHIFU treatment using the FocalOne® device. We then carried out a study on anatomical specimens to assess the limiting factors of the FocaleOne® probe and to test another HIFU probe, which has smaller transducer and which is mounted on a flexible endoscope. We also performed an observational clinical study to measure the acoustic attenuation of rectosigmoid endometriosis lesions and that of normal bowel. Finally, we have developed a murine model of subcutaneous endometriosis to assess the pathophysiological effects of HIFU on endometriosis.

RESULTS: We included 23 patients in the phase I clinical trial between June 2015 and October 2019. Treatment was carried out in 20 of these patients (87% feasibility). No serious adverse events have been reported. We did not find a significant morphological effect at 6 months, but we report a significant improvement on digestive and gynecological symptoms as well as on patients’ quality of life. Studies on anatomical specimens and on MRI pictures demonstrated the role of the sacrum and the recto-sigmoid hinge in the mechanical limitations of the FocalOne® probe. The use of a smaller probe with a shorter focal could be interesting in order to increase the feasibility of the treatment. Our study on 13 patients treated surgically for rectum or sigmoid endometriosis nodule, showed that attenuation of digestive endometriosis at 3 MHz is 50.2 Np / m. This value was significantly higher than attenuation of the normal bowel (32.8; p <0.001). We finally showed that the heterologous subcutaneous murine model "BALB / c-nude # Ishikawa" was reliable and efficient to study the effects of HIFU on digestive endometriosis, as the acoustic attenuation of its nodules are remarkably close to that of endometriosis lesions. Thanks to this model, we reported that HIFU lesions are associated with a higher rate of ischemic and coagulation necrosis.

CONCLUSIONS: Treatment with TR-USgHIFU in rectosigmoid endometriosis is feasible and safe. Its morphological efficacy remains to be demonstrated, but its significant clinical efficacy is promising. It could become be a minimally invasive alternative to replace surgical treatment in this indication, especially for rectal lesions.

Charles-André PHILIP was born in Lyon, France, in 1986. He obtained is MD degree from University Claude Bernard (Lyon, France), in 2014 and is specialized in Obstetrics and Gynecology. He obtained his Master of Science in Oncology from Lyon 1 University (Lyon, France) during his fellowship in the Lady Davis Institute for Medical Research at McGill University (Montreal, Canada) in 2015. 
His main clinical and research fields are endometriosis and oncology. He completed a 2 years fellowship in Gynecology-Obstetric in Croix-Rousse University Hospital (HCL, Lyon, France) and contributed with Pr. Gil Dubernard to the description and evaluation of 3D-Rectosonography, a new procedure combining tridimensional sonography and intra-rectal contrast for the diagnosis of rectal endometriosis