Bowel Endometriosis: Causes, Symptoms, and Treatment

Understanding the Pain and Symptoms of Bowel Endometriosis

Endometriosis affects roughly 11% of women worldwide, predominantly those of reproductive age. A more specific manifestation is bowel endometriosis, which impacts around 5% to 12% of individuals diagnosed with endometriosis. This guide explores the nature of bowel endometriosis, including what it feels like, its symptoms, possible causes, how it is diagnosed, and current treatment approaches.

What Is Bowel Endometriosis?

Bowel endometriosis occurs when endometrial-like tissue, which typically grows inside the uterus, develops on or within the bowel walls. This involvement can produce a range of gastrointestinal symptoms that may substantially diminish quality of life. In many cases, bowel symptoms arise due to intensely inflammatory endometriosis lesions on the peritoneum in the pelvis and abdomen, even without direct bowel implants.

Where Does Bowel Endometriosis Occur?

The rectum and sigmoid colon are affected in approximately 90% of bowel endometriosis cases. Other sites can include the appendix, small intestine, stomach, and additional portions of the large intestine.

Symptoms of Bowel Endometriosis

The symptoms often resemble those seen with other gastrointestinal disorders, including small intestinal bacterial overgrowth (SIBO), which can complicate and delay diagnosis. Symptom intensity can range from mild to severe and frequently fluctuates with the menstrual cycle.

Common bowel-related symptoms can include abdominal pain—particularly in the lower quadrants—bloating often called “endo belly,” changes in bowel movements such as constipation or diarrhea, nausea and vomiting, pain during bowel movements that may increase during menstruation, and rectal bleeding.

Non-bowel symptoms may occur as well. These can include chronic pelvic pain, difficulties with fertility, painful sexual intercourse, pain during urination, a sensation of pelvic heaviness, fatigue, and impaired psychological well-being.

Causes of Bowel Endometriosis

The exact cause remains unknown. Two often-quoted theories are Mullerianosis of embryogenic origin and retrograde menstruation. Mullerianosis of embryogenic origin proposes that developmental abnormalities place cells in atypical locations that later become endometriosis, with potential genetic, genomic, and immunologic influences. Retrograde menstruation suggests menstrual blood can flow backward through the Fallopian tubes into the pelvis, potentially leading to endometriosis. Because most women experience retrograde menstruation while only about 10% develop endometriosis, this theory alone is considered antiquated and has been challenged. It is more likely that a combination of embryologic, molecular, immunologic, and genetic factors underlies the condition, and this mix may vary between individuals.

Diagnosis of Bowel Endometriosis

Diagnosis is often complex. Clinicians typically use a combination of detailed symptom history, physical examination, imaging such as ultrasound or MRI, and sometimes minimally invasive laparoscopic or robotic surgery. Delays in diagnosis are common due to overlap with other gastrointestinal conditions. Imaging can aid diagnosis and help map disease for surgery, but it is not reliable enough to exclude the diagnosis of endometriosis.

Misdiagnosis

Misdiagnosis frequently occurs, with irritable bowel syndrome (IBS) and other gastrointestinal disorders often suspected first. A high index of suspicion is essential, and bowel symptoms that correlate with the menstrual cycle warrant careful evaluation.

The Role of Minimally Invasive Surgery

Surgery with biopsy is considered the “gold standard” for diagnosing endometriosis, including bowel involvement. This approach can provide a more accurate assessment and clarify the extent of scar tissue and endometrial-like tissue. Ideally, the surgeon should be prepared to perform therapeutic surgery at the same time as diagnostic surgery. A poorly executed procedure is worse than no procedure at all if the surgeon is unprepared and resorts to fulguration (burning) of lesions instead of proper excision. If diagnostic surgery reveals disease that the surgeon is not prepared to excise appropriately, it is better to conclude the procedure and refer the patient to an appropriate surgeon.

Treatment of Bowel Endometriosis

Treatment often involves surgery, as medical management has generally been deemed ineffective for these specific lesions. The surgical approach depends on the extent and location of disease. In many cases, hormonal options may also be recommended after surgery to reduce recurrence risk; while better surgery reduces the likelihood of needing postoperative hormonal therapy, there are exceptions.

Surgical Treatment

Surgical management typically aims to remove all peritoneal lesions using an excisional technique. In cases of deeply infiltrating endometriosis, the strategy may differ based on whether the rectal wall or the mesentery—where the blood vessels to the rectum are located—is involved. Options include shaving, nodulectomy, disc resection, and bowel resection. The operating surgeon should be capable of performing any of these procedures as required. In some situations, the primary excision surgeon can address bowel disease if they have the appropriate bowel surgery training and hospital privileges; in other cases, a second surgeon may serve as part of a backup team. It is best to discuss the potential need for bowel surgery and available options before the operation rather than facing an emergency during surgery when the right specialists may not be immediately accessible.

Lifestyle Changes

Lifestyle adjustments may help manage symptoms alongside medical and surgical care. Some people find that particular foods or habits—such as stress or irregular sleep—trigger symptoms. Tracking potential triggers in a journal and consulting a healthcare provider or nutritionist when considering dietary changes can be beneficial.

Coping with Bowel Endometriosis

Living with bowel endometriosis can be challenging, but with accurate diagnosis, appropriate treatment, and effective symptom management, individuals can lead fulfilling lives. Open communication with healthcare providers about symptoms and concerns supports timely diagnosis and informed treatment planning.

In summary, bowel endometriosis is a painful and often misunderstood condition. Greater awareness and understanding can promote earlier diagnosis, more effective treatment, and better quality of life. If you suspect bowel endometriosis or recognize any of the described symptoms, seek medical advice without delay.