Endometriosis Bowel Symptoms: Pain, Relief, and Surgery

Endometriosis is a full-body inflammatory disease in which tissue similar to the lining of the uterus grows outside the uterus. Historically, it has been a misunderstood disease thought to affect mainly reproductive organs. However, endometriosis lesions have been found on every organ, including the bowels.

According to research from 2020, 10% to 12% of people assigned female at birth have endometriosis, and 5% to 12% of those people have bowel involvement. You don't need to have endometrial lesions growing on your bowels to experience bowel symptoms, such as constipation, diarrhea, pain with bowel movements, and more.

In this article, learn more about bowel endometriosis and bowel-related endometriosis symptoms.

Bowel Symptoms of Endometriosis

Endometriosis is generally thought of as a disease that causes infertility and painful periods. While these are both symptoms of endometriosis, they do not fully and accurately portray the disease's symptoms.

Endometriosis can affect any organ, leading to painful sex, pain unrelated to menstruation, painful urination, bowel symptoms, and more. This, in turn, may contribute to the notable delay in diagnosis that most people with endometriosis experience.

Gastrointestinal symptoms are fairly common in endometriosis and should not be overlooked.

Some bowel symptoms of endometriosis include:

• Abdominal pain and bloating
• Constipation
• Diarrhea
• Flatulence (passing gas)
• The urgency to defecate (poop)
• Nausea or vomiting
• Pain with bowel movements
• Intestinal symptoms that adversely impact daily life

Lesion Location and Associated Symptoms

You do not need to have endometriosis lesions growing directly on your bowels to experience bowel symptoms.

One study found that, compared to participants without endometriosis, people with endometriosis had significantly more severe gastrointestinal symptoms unrelated to the location of endometriosis lesions. The one exception was that people with bowel endometriosis lesions were more likely to have nausea and vomiting.

Another study found that irritable bowel syndrome (IBS) is more commonly diagnosed among people with endometriosis than among the general public, regardless of endometrial lesion location.

Nature of Bowel Endometriosis Pain

Endometriosis can cause significant pelvic and abdominal pain. However, the pain pattern, location, intensity, and duration differ significantly from person to person.

Sensation

The sensation of endometriosis pain may feel like:

• Aching
  
• Burning
• Cramping
• Pushing or squeezing
• Stabbing
• Waves
  

Frequency 

The frequency of endometriosis pain differs from person to person.

In one 2021 study, these four patterns of endometriosis pain were found:

• Cyclical: Pain worsening around menstruation
• Constant: Daily pain, all month long
• Random: No consistency, intermittent pain that is unpredictable
• Changing: A change in pattern, usually worsening or becoming more frequent over time

Location and Depth

Endometriosis lesions are found on the rectum and sigmoid colon in about 90% of bowel endometriosis cases. Bowel endometriosis lesions can be located on the following:

• Small intestine
• Large intestine
• Sigmoid, rectum, or cecum (parts of the colon)
• Appendix

Bowel endometriosis lesions often present as one single nodule with a diameter greater than 1 centimeter (cm). However, endometriosis lesions can be any size, depth, and color.

Causes

Endometriosis is a complex disease, and there are multiple causes for bowel symptoms, including the following:

• Inflammatory mediators: Compounds responsible for inflammation can lead to constipation, diarrhea, bloating ("endo belly"), and other bowel symptoms.
• Bowel obstruction: In rare cases, deep endometriosis can grow into the intestinal wall, causing obstructions or narrowing, leading to bowel symptoms.
• Pelvic floor dysfunction: The inability to coordinate pelvic floor muscles can cause constipation or diarrhea, pain with bowel movements, and more.
• Dysfunction or dysregulation of nerves: Endometriosis lesions can irritate the nerves around the bowels, leading to bowel pain, pain with defecation, and issues with constipation or diarrhea.

Diagnosing Bowel Endometriosis

The only definitive way to diagnose endometriosis is through a biopsy. When performing a biopsy, your provider takes a sample of the affected tissue and sends it to a lab for a specialist called a pathologist to examine under a microscope and provide a diagnosis.

Supplementary Testing

If your provider suspects bowel endometriosis, they may recommend various supplementary tests before surgery to assist in surgical planning. These tests might include:

• Pelvic examination
• Magnetic resonance imaging (MRI)
• Transvaginal ultrasound (TVUS)
• Colonoscopy

Complications During Surgery 

General gynecologists may leave bowel endometriosis untouched during excision surgery (surgery to remove endometrial lesions and surrounding tissues) to avoid complications. An endometriosis specialist who uses the excision technique should perform the surgery, especially with the prospect of bowel involvement. A colorectal surgeon may often present in cases where bowel involvement is highly suspected.

Complications can happen during any surgery, including surgery for endometriosis on the bowels. Complications can include the following:

• Anastomotic leakage: Gut leakage when the surgical site is not sealed properly
• Rectovaginal fistula: An opening between the vagina and the rectum
• Pelvic abscesses: A collection of fluid in the pelvic region

Your surgeon should inform you of possible complications and also provide their complication rates based on previous surgeries.

Treatment Options for Relief

Excision surgery is the gold standard for diagnosing and treating endometriosis. However, excision surgery is not recommended or accessible to everyone. Your provider may also recommend certain medications or physical therapy to relieve endometriosis symptoms.

Excision Surgery

Excision surgery to treat bowel endometriosis may involve one or more of these surgical techniques:

• Rectal shaving: The endometriosis lesion is "shaved" or cut out from the surface of the bowel. This technique is the least invasive and is appropriate for lesions less than 3 cm in diameter and less than 7 millimeters (mm) in depth.
• Disc excision: A surgeon may cut out a portion of the bowel wall and staple the opening together. This technique is usually reserved for endometriosis lesions less than 3 cm in diameter that do not take up more than 60% of the bowel circumference.
• Segmental resection: In this most invasive technique, a surgeon removes a section of the bowel and sutures the remaining sections together. This technique is only done for the deepest and most advanced endometriosis lesions.

Other Treatments

Most general gynecologists use the ablation technique of endometriosis surgery, in which endometriosis lesions are burned off. With this technique, deeper endometriosis may remain under the burned surface and cannot be confirmed by a pathologist, which is problematic in cases of deeper bowel nodules.

Some healthcare providers may prescribe medications to manage symptoms, including birth control and pain medications. These medications do not slow the progression of endometriosis nor reduce the size of endometriosis nodules. However, they may help reduce pain or other symptoms and improve quality of life.

Your provider may recommend pelvic physical therapy to help reduce pelvic pain, treat pelvic floor dysfunction, and reduce pain with bowel movements. This treatment method can improve symptoms and quality of life but does not address the underlying cause of endometriosis lesions.

Summary

Gastrointestinal symptoms are common with endometriosis, regardless of whether lesions are growing on the bowels. Excision surgery with an endometriosis specialist is the gold standard for diagnosing and treating bowel endometriosis. However, complications can occur, and you should receive full informed consent from your surgeon before deciding on the best treatment plan.