Bowel endometriosis is a chronic condition where tissue similar to the lining of the uterus grows outside the uterus, specifically on or within the bowel. This misplaced tissue responds to hormonal changes, leading to inflammation and pain. Bowel involvement occurs in approximately 5% to 12% of women with the disease. The rectum and sigmoid colon are the most frequently affected parts of the bowel, accounting for up to 90% of all intestinal lesions.
Recognizing the Symptoms
Recognizing bowel endometriosis symptoms is challenging because they often resemble other common gastrointestinal disorders, such as irritable bowel syndrome (IBS). A distinguishing factor is the cyclical nature of symptoms, often worsening during or around the menstrual period. Digestive symptoms can include painful bowel movements (dyschezia), constipation, diarrhea, bloating, and abdominal cramps. Some individuals may also experience rectal bleeding during menstruation, though this is less common.
Beyond bowel-specific issues, individuals may also experience general endometriosis symptoms, including chronic pelvic pain, painful periods (dysmenorrhea), and pain during sexual intercourse (dyspareunia). The severity and type of symptoms can vary widely among individuals and depend on the location, size, and depth of the endometriotic lesions on the bowel.
Initial Medical Evaluation
The diagnostic journey for bowel endometriosis begins with a thorough initial medical evaluation. This involves a detailed patient history, discussing the nature, severity, duration, and cyclical pattern of symptoms. Understanding the patient’s medical history, including any prior diagnoses of endometriosis, also provides important context.
Following the history, a physical examination is usually conducted, often including a pelvic exam. During this exam, a doctor might palpate for tenderness or the presence of nodules, particularly in areas like the rectovaginal cul-de-sac or uterosacral ligaments, which can be suggestive of deep infiltrating endometriosis. While these initial steps guide further investigations, they are rarely sufficient for a definitive diagnosis of bowel endometriosis.
Diagnostic Imaging and Endoscopy
Several imaging and endoscopic tests investigate suspected bowel endometriosis. Transvaginal ultrasound (TVUS) is often a first-line imaging technique due to its accessibility and ability to provide detailed views of pelvic organs. Experienced sonographers can visualize deep infiltrating endometriosis on the bowel wall, often appearing as irregular, hypoechoic nodules, particularly in the rectosigmoid colon. Transrectal ultrasound (TRUS) can also be valuable for assessing rectal endometriosis, especially for lesions within the muscular layer of the bowel wall.
Magnetic Resonance Imaging (MRI) serves as a second-line diagnostic tool, offering detailed images of the pelvic organs and helping to identify the extent and location of bowel lesions. MRI can detect deep infiltrating endometriosis by showing characteristic changes in bowel wall signal intensity and thickness. While Computed Tomography (CT) scans have a more limited role in directly visualizing endometriosis, they can be used to rule out other conditions that cause similar symptoms.
Endoscopic procedures like colonoscopy and sigmoidoscopy allow direct visualization of the inner lining of the bowel. However, endometriosis typically affects the outer layers of the bowel wall, meaning direct visualization of endometriotic lesions is often not possible unless the disease is very severe and has penetrated the mucosal layer. Biopsies taken during colonoscopy are frequently negative for endometriosis, even when present, because the tissue is usually located beneath the mucosal surface. Therefore, while useful for ruling out other intestinal conditions, colonoscopy is not a primary diagnostic tool for most cases of bowel endometriosis.
Definitive Surgical Diagnosis
Laparoscopy stands as the gold standard for definitively diagnosing bowel endometriosis. This minimally invasive surgical procedure is performed under general anesthesia. During laparoscopy, a small incision is made, typically near the navel, through which a thin tube with a camera (laparoscope) is inserted into the abdominal cavity. This allows the surgeon to directly visualize the pelvic organs and the surface of the bowel for any signs of endometriotic implants.
The surgeon can identify lesions, which may appear as brown or reddish spots, nodules, or fibrous tissue. During this procedure, a biopsy of any suspected tissue is taken. This tissue sample is then sent for histopathological examination, where a pathologist microscopically confirms the presence of endometrial glands and stroma, which is necessary for a definitive diagnosis. Laparoscopy often serves a dual purpose, as the surgeon can frequently remove or treat the identified lesions during the same operation, addressing both diagnostic and therapeutic needs.