EDAP Completes Phase 3 Enrollment for Focal One HIFU Therapy in Rectal Endometriosis Study

Rectal endometriosis is a condition where tissue similar to the lining of the uterus grows outside the uterine cavity, affecting about 10-12% of women of reproductive age. It often occurs in the peritoneum or in organs like the bowels, appendix, and pancreas. The area between the uterus and the rectum is a common site for this condition, leading to rectal endometriosis.

The rectum, a part of the large intestine, stores feces temporarily and helps maintain continence. In women, the rectum is situated behind the cervix, uterus, and vagina, with a peritoneal layer covering part of it and forming the rectouterine pouch, which can be affected by diseases like endometriosis.

Bowel endometriosis, which can involve the rectum in about 90% of cases, is often misdiagnosed as irritable bowel disease or Crohn’s disease. Symptoms that align with menstrual cycles might indicate bowel endometriosis. The condition typically affects the outer layer of the bowels, but in deep-infiltrating endometriosis (DIE), lesions exceed 5 mm and affect deeper muscular layers.

The exact cause of bowel or rectal endometriosis remains unclear. The retrograde menstruation theory suggests that endometrial tissue can be deposited outside the uterus. Other theories involve gene regulation dysfunction, stem cell implantation, and changes in the immune environment around the peritoneum. Oxidative stress and reactive oxygen species may also contribute to the proliferation of endometrial tissue.

Symptoms of rectal endometriosis include pain during defecation, constipation during monthly cycles, and rectal stenosis in about 26.4% of diagnosed women. These symptoms can mimic those of irritable bowel syndrome or colonic adenocarcinoma. The severity of symptoms does not always correlate with the extent of the disease or lesion size.

Diagnosis involves a physical examination and imaging techniques like transvaginal ultrasound and MRI. Transvaginal ultrasound is particularly effective for detecting DIE in the rectum. Other methods include colonoscopy, double-contrast barium enema, and CT scans. However, a definitive diagnosis requires laparoscopic excision, biopsy, and histopathological markers identification.

Treatment typically involves surgery to remove the lesions. The extent of surgery depends on lesion size, the presence of fibrotic tissue, lesion depth, bowel involvement, distance to the anus, and lymph node involvement. A multidisciplinary approach is necessary to assess all risks. Laparoscopic deep excision surgery is the preferred method, and surgeons may consider a stoma if lesions are close to the anal margin.

Rectal endometriosis can significantly impact a woman's quality of life, causing painful symptoms. Accurate diagnosis and treatment are essential to manage this chronic condition effectively.