Bowel Endometriosis Surgery and IBS

Overview

Endometriosis can spread to a variety of locations, and one of the major reasons why patients are not satisfied with their endometriosis surgery is because there are times when their bowel symptoms go ignored and their bowel lesions are not recognized during surgery. Even worse, patients are often misdiagnosed with Irritable Bowel Syndrome (IBS) or Crohn’s disease, as physicians mistakenly attribute the patient’s symptoms as having a gastrointestinal cause. While it is easier to catch bowel obstruction and lesions that appear on MRI and contrast studies showing narrowing of the bladder, when these lesions are small and there is a multitude of them, they can very easily escape the surgeon’s eye, even upon laparoscopic surgery. Only if a surgeon is properly trained and specifically asks about the symptoms and questions that indicate the presence of bowel endometriosis, will these lesions get recognized during surgery. These consist of asking whether or not a patient’s bowel symptoms are in sync with their menstrual cycle. If these questions are not asked and the surgery team is not alerted beforehand, then the lesions will go unnoticed, unremoved and untreated. For these reasons, we find it highly important for our patients to be aware of what bowel endometriosis is, why is it often misdiagnosed, and how it should be properly treated.

Highlights

What is bowel endometriosis?

Endometriosis is the spread of tissue from the lining of the uterus (endometrium) to other parts of the body. One common area in which these lesions can affect is the intestines, rectum and associated peritoneum covering the pelvic side walls. When this occurs, the endometriosis tissue implants itself outside of the bowel walls and continues to grow and menstruate, causing inflammation and such symptoms as belly pain, painful bowel movements and more. The bowels can be involved at the serosal level (outer layer of a bowel) or muscularis level (further embedded into the tissue), and are usually in about 18% of all endometriosis cases. [1]

Where does bowel endometriosis occur in the body?

In bowel endometriosis, lesions implant onto a multitude of areas outside the uterus. Below are just a few common sites in which bowel endometriosis can arise:

• Peritoneum: This is arguably the most common site for endometriosis lesions to latch onto. While the lining of the abdomen does not make up for the bowels themselves, peritoneum endometriosis can give all the symptoms of bowel endometriosis and is thus important to evaluate in any endometriosis surgery, including bowel endometriosis cases.
• Cul-de-sac (pouch of Douglas): The bowels around the posterior cul-de-sac (the area between the uterus and rectum), also known as the pouch of Douglas, is one of the most common sites of bowel endometriosis. In this area, the rectum and vagina face each other and are divided by a recto-vaginal septum. Endometriosis in the pouch of Douglas can cause symptoms that not only include painful bowel movements, but also painful sex as the inflamed affected tissue can infiltrate to the outer wall of the vagina.
• Rectum: Endometriosis can implant onto the outside of the rectum, causing severely painful bowel movements, constipation, and even rectal bleeding.
  Perirectal area- This is the area directly behind the rectum, and bowel endometriosis lesions that implant in this region are associated with symptoms of back pain.
• Colon and small intestine: Lesions can attach anywhere on the outside of the intestines themselves. This can often be tricky to spot as it requires a very skilled surgeon with a keen eye to expect the intestines by “running” through them and checking for any suspected lesions.
• Appendix: Often lesions that come from appendix or near small intestine, give more symptoms of gas and pain on the right side (particularly the right lower quadrant).

How is bowel endometriosis organized?

Overall, the lesions of the bowel can be multi-focal or multi-centered. Multi-focal means that lesions will be around the same area, but there are multiple locations within that area of tissue. For example, in the rectum or upper vagina, but with multiple lesions within those areas. Multi-centered lesions are localized to the bowels but are spread diffusely throughout the rectum, colon, appendix, etc. In our own clinical setting, we have found that about 10-15% of our endometriosis cases have nodules that are multi-centered, whereas 20% of the time the lesions are multi-focal. [2]

What are the symptoms of bowel endometriosis?

Symptoms presented by patients with bowel endometriosis are more specific to those of bowel disorders, and due to this are more likely to be misdiagnosed as symptoms of bowel disorders such as IBS, appendicitis or even Crohn’s disease. For these reasons, it is important to understand the similar symptoms between the two diseases, as well as the key details that separate them. Symptoms unique to bowel endometriosis, include:

• Painful bowel movements, bowel spasms, and rectal pain, particularly increasing during periods.
• Bloody stool while rare, should be an indication of extensive endometriosis involvement.
• Constipation conspicuously prominent during periods.
• Diarrhea and constipation alternating (some patients have diarrhea first then constipation, while others have the reverse).
• Abnormal gas, especially during periods.
• Bloating (fluid congestion).
• Abdomen tenderness, especially in the right lower quadrant due to possible appendix infiltration.
• Painful sex (dyspareunia), due to infiltration of endometriosis to the rectum and posterior cul-de-sac of the uterus.

A key distinction to make in differentiating bowel symptoms due to gastrointestinal diseases, versus those caused by bowel endometriosis, comes in their occurrence with a woman’s menstrual cycle. Often times, bowel dysfunction caused by bowel endometriosis will be in sync with a woman’s period, or at least alternate in varying levels during different points in their ovulation cycle. This is important to note as sometimes a gastroenterologist will not make this distinction, as it lies outside of the scope of their common practice. Nevertheless, this is a key distinction to make as this can be the difference between receiving the right diagnosis versus a “dump diagnosis.”

Diagnosing

How is bowel endometriosis diagnosed?

• Pelvic exam with sonogram- While this clinical form of testing cannot provide a formal diagnosis of endometriosis, it can be helpful for your surgeon to do in order to assess points of tenderness. By performing a rectovaginal exam, an experienced surgeon can identify the specific locations of point rectal tenderness. This coupled with sonographic imaging can help provide a presumptive diagnosis as to whether or not the rectum, and in turn the bowels, will be involved.
• Imaging tests- Additional tests like MRI and a dual contrast CT scan are necessary to evaluate the condition of the ureters and higher bowel involvement, particularly in the appendix area. The appendix is one of the first organs that often gets infiltrated in cases of bowel endometriosis. For this reason, it can be a key finding in presumptively diagnosing endometriosis before surgery.
• Laparoscopy- In order to formally diagnose and treat bowel endometriosis, laparoscopic surgery must be performed in the operating room. During this procedure, small incisions are made into the abdomen, which allows the surgeon to insert operating instruments and a laparoscope (small camera) that is then used to visualize and evaluate the inner abdominal anatomy. Using this technique, a highly skilled surgeon can navigate through the bowels, which includes the sigmoid colon, small intestines, appendix, etc. and thoroughly inspect them for any suspected endometriosis lesions. Excision of these lesions or complete resection of parts of the bowels will then be conducted depending on the severity of the disease, all of which will be done under laparoscopic visualization, ensuring minimal invasive surgery and optimal recovery.

Why is bowel endometriosis often misdiagnosed?

Clinically bowel symptoms are some of the most prominent of endometriosis symptoms, even in cases of adolescents. Endometriosis symptoms will thus often start with bowel symptoms (diarrhea, constipation, etc.), and for these reasons, patients will seek a gastroenterologist, who will attribute the symptoms to such causes as irritable bowel syndrome (IBS), appendicitis, Crohn’s disease or even colon cancer.[3] These diagnoses will be made without biopsy samples or a pathology report being obtained. Instead, patients will go on and receive multiple colonoscopies and endoscopies and be diagnosed with IBS, or other bowel disorders, without a full evaluation of what really may be the underlying cause of the bowel symptoms. For these reasons, we consider an IBS diagnosis without evaluation for endometriosis to be a “dump diagnosis” for a patient’s bowel dysfunction and pain, particularly if they have endometriosis symptoms, which will coincide with the patient’s period. Patients who receive a misdiagnosis such as this, will go on to be improperly treated and have their symptoms persist, only to find out years later that the true underlying cause is in fact endometriosis. In these instances patients can go 5 to 10 years without being treated, sometimes missing the prime reproductive years of their life.

How come a colonoscopy cannot be used to diagnose bowel endometriosis?

Inflammation of the bowel caused by IBS will come from inside the intestines, whereas endometriosis lesions will latch on to the outside of the bowels and cause inflammation. Procedures such as colonoscopies and endoscopies are scopes that exam the inside of the bowels, which means that they are unable to detect bowel endometriosis lesions. Nevertheless, it is not uncommon to see these patients misdiagnosed with gastrointestinal diseases, without any knowledge or mention of endometriosis. This misdiagnosis is not a matter of the quality of the physician, but rather a matter of finding the right physician for your particular case. A physician well equipped to evaluate cases of suspected bowel endometriosis, will not only have great experience in the field, but they will also possess the skill to perform laparoscopic surgery, the only formal way of definitively diagnosing endometriosis.

Treatment

How is Bowel Endometriosis Surgically Treated?

When a surgeon looks into the abdomen using laparoscopy, one of the first steps of the procedure should be to evaluate the appendix and ileum of the small intestine. The surgeon will then perform a procedure called, “running the bowels,” which is when they ‘run through’ all of the small intestine, like unwinding a fish hook, all the way to the stomach and check for any suspected lesions or deformity. The diaphragm and colon (large intestine) will then also be checked. In cases of redundant colon, which is an abnormally long large intestine that causes widening of the intestine right before the rectum, this “running” procedure is particularly important as the sigmoid (S-shaped extra colon) must be mobilized completely. It is also important to note that this technique takes great skill, and is part of the reason why bowel endometriosis cases are so complicated and present more risk. In turn, this procedure should only be performed by those with great vast experience. Once the intestines have been unwound and freed, a rectal probe is put in with a manipulator in order to perform a thorough examination of the rectum and associated rectal vaginal symptoms. The surgeon will then be able to check the bowels for suspected lesions and remove them accordingly, using their preferred technique. The treatments for bowel endometriosis are either removal of the nodule(s), most of the time including the full thickness of the wall (90%), but If the nodules are multiple and obstructive, the treatment is bowel resection surgery. This is particularly difficult and requires special skills in colorectal surgery.

Will a hysterectomy treat bowel endometriosis?

A hysterectomy is only performed if highly advised by one's gynecologist and if the patient is comfortable with such a procedure. However, it is by no means a definitive treatment for bowel endometriosis or even endometriosis. Hysterectomies are often mistakenly viewed as surgical treatment options for patients with endometriosis [4], when really oftentimes the best form of treatment is minimally invasive excision or resection surgery, especially when it comes to bowel endometriosis. By removing the uterus, you may be eliminating the endometrial lining from which the endometriosis tissue derives from, but you are not treating the endometriosis that has already grown and spread in areas such as the intestines, rectum, appendix and etc. In fact, if left untreated, these lesions will remain and grow causing bowel endometriosis to persist even after a hysterectomy surgery. Therefore, it is important to keep in mind when choosing a doctor that they are fully aware of not only checking for endometriosis in the bowels but also having the skill and experience to remove such lesions, even if the plan of treatment is a hysterectomy. Nevertheless, a hysterectomy may be beneficial in cases of extensive bowel endometriosis. Thus this is something to discuss with your surgeon and is precisely why it is so key to choose a surgeon you are comfortable with.

What to expect the day before bowel endometriosis excision surgery?

The day before your surgery, it is incredibly important that patients adhere to the strict bowel preparation regime provided the day before your surgery. This ensures that the patient’s bowels are as clear and empty as possible during their surgery, which ultimately makes the bowels themselves much easier to navigate and manipulate by the surgeon. The following is our own bowel prep instructions, which we advise to all of our patients, especially bowel endometriosis cases:

• Have a light/normal breakfast.
• Have a light lunch.
• Drink lots of clear liquids during the entire day.
• At 5 pm limit dinner to clear liquid dinner (ex.broth, jello, liquids, etc.)
• At 12:30 pm drink 10 ounces Magnesium Citrate either straight or mixed. You will develop diarrhea. It can happen as quickly as 30 minutes or up to several hours. Continue with clear liquids up until 12:00 midnight.
• You will be given 1 white pill, Cytotec. Insert this pill vaginally at 12 pm the day before your surgery. This may cause slight cramping or vaginal bleeding. This is normal.
• Do not eat or drink anything after 12:00 AM (midnight)

What is the recovery time of bowel endometriosis surgery?

In general, as long as the operation is performed laparoscopically, which for our cases are all of our surgeries, the recovery time is no different than any other standard laparoscopy procedure, and patients are able to be discharged within the day of their surgery. However, for patients who undergo suturing of bowels (conservative surgery), it is advised to stay overnight in the hospital until they pass gas and have their first bowel movement. It is important to note, however, that bowel endometriosis surgery is some of the most difficult and specialized forms of surgery, and for these reasons, complications can often arise. In fact, even with most precise, skillful surgery, 1 of 20 bowel endometriosis cases present some form of perioperative complication.

What to expect the days after bowel endometriosis surgery?

Following bowel endometriosis surgery, you can expect your bowels to be very sensitive and require a few days to rest before resuming normal function. Below are just a few of the common complications that will arise for a few days following bowel endometriosis surgery, along with suggestions to help relieve these symptoms:

• Bloatedness causing back and shoulder soreness: During bowel endometriosis surgery, your abdomen will be filled with gas in order to lift the abdominal walls away from the cavity to get a better view of the bowels. After surgery, some of this gas will remain, but there are some remedies for relieving this. Gas-X® is one recommendation we often give to patients, as the active ingredient Simethicone, breaks up the surface tension of trapped gas and allows your system to easier expel this gas.

• 

  Abnormal and painful bowel movement: Often times the first bowel movement following bowel endometriosis surgery can be a tricky one, causing pain and discomfort to the patient. While some physicians recommend the use of narcotic pain medications in these instances, we have found that they can also cause constipation. We instead advise drinking at least 64 ounces of water a day and sometimes even a mild stool softener, such as Colace, if needed. We also recommend keeping your diet light for the first few days (broths, jell-O, and other easily digested food), to give your body the time it needs to recover.

What risks are involved in bowel endometriosis surgery?

Bowel endometriosis surgery is one of the most difficult procedures to perform. It requires great experience and meticulous attention to detail, as a surgeon must go through the entirety of the intestines, from the rectum to the small intestines. For these reasons, bowel surgery with endometriosis is the riskiest of any other endometriosis surgery. In our experience, nearly 1 out of 20 cases (5%) experience complications following surgery, which can include bloatedness, gassiness, abdominal and rectal pain, etc. While this is a very promising recovery number for a procedure that only a select few can perform and can have a tremendous impact on a patient’s relief of symptoms, we feel it is very important for the patient to be aware of the potential risks.

Can a diet relieve bowel endometriosis symptoms?

A change in diet and lifestyle can be used as a complementary measure in the treatment of bowel endometriosis, particularly pre and post surgery. As noted earlier, bowel endometriosis symptoms such as bowel movement pain (constipation), diarrhea, abnormal gas and bloating, are very similar to those of bowel disorders, such as irritable bowel syndrome (IBS). The distinction comes in the fact that bowel endometriosis symptoms will likely come in synch with a woman’s menstrual period, while IBS symptoms will show no relation. This is a subtlety that many neglect to discern and for this reason, bowel endometriosis can often be misdiagnosed as IBS or other similar gastrointestinal diseases, preventing the patient from receiving the proper treatment that they may in fact need. Nevertheless, these symptom similarities can be manipulated in treatment efforts that provide a great advantage for patients suffering from bowel endometriosis. In other words, by using similar GI treatment measures, physicians can help relieve the highly similar symptoms of bowel endometriosis. The prime example for this is in certain recommended diets.

What diet can help relieve bowel endometriosis symptoms?

A change in diet is often highly recommended in IBS patients in order to relieve symptoms. In turn, the same can be applied to cases of bowel endometriosis. One study found that a low FODMAP diet can a highly beneficial measure for relieving bowel dysfunction symptoms in endometriosis patients.[5] FODMAP is an acronym for “Fermentable oligosaccharides, disaccharides and monosaccharides, and polyols.” These are molecules, mainly carbohydrates with the exception of polyols (an alcohol), that are found in foods and can be poorly absorbed by some human GI tracts. Generally, a low FODMAP diet, therefore, consists of a low intake of carbohydrates and gluten. It also consists of several specific high FODMAP foods to avoid and low FODMAP foods to intake. While this diet may seem difficult to adopt at first, it can be highly beneficial in the long run, especially when it comes to helping ease symptomatic pain pre-endometriosis surgery or as a cautious measure undertaken post surgery. In addition to this, a change in diet can affect how a patient feels, which is often a subject of issue for patients suffering from endometriosis. Nevertheless, it is also important to note that a diet is no substitution for surgery, especially when in the hands of a highly skilled and specialized laparoscopic surgeon. It is strictly used to help relieve symptoms, and not to treat the underlying cause. Also, before changing your diet it is highly advised to consult your primary doctor or seek the help of a professional nutritionist.

Our View

What is our technique in surgically treating bowel endometriosis?

About 1 out of 4 of our endometriosis cases involve the bowels, which is a bit higher than the normal amount of bowel endometriosis cases out of the average endometriosis patient. For this reasons, we take both great pride and care in surgically treating bowel endometriosis. Having practiced our endometriosis laparoscopic surgery technique for several decades now, our team has great skill in handling even the most complex cases of bowel endometriosis, while at the same time ensuring a minimally invasive surgery.
As discussed earlier, once we make incisions into the abdomen and insert a laparoscope, we first check the appendix and ileum of the small intestine, as these are common sites in which bowel endometriosis lesions often implant. We will then meticulously and thoroughly unwind the intestines, a technique termed “running the bowels,” and insert a rectal probe with a manipulator. This mobilizes the intestines making them accessible to examine and operate on, but then comes the hard part, identifying and removing suspected endometriosis lesions.

In order to identify bowel endometriosis, a surgeon must not only be looking for these specific lesions, but they must also be capable and have a tremendous amount of experience in repairing the bowels, rectum and sigmoid colon. This is arguably the most difficult part of bowel endometriosis surgery and is why so many endometriosis cases go untreated properly. On top of training in laparoscopic surgery and proper identification techniques of endometriosis, if a surgeon is to perform excision of endometriosis they must also have the skill to restore, reconstruct and repair the infected organs. This is because many endometriosis lesions are difficult to remove without cutting into the mucosa, especially when the lesions are involved at the muscularis level. In other words, these nodules are transmural with full thickness involvement (buried within the muscular tissue), and will thus require distortion of the normal bowel anatomy so that the lesions can be removed. This will then require anatomical repairing then after.

Over the years, we have mastered the technique of proper restoration of the bowels original function once endometriosis lesions are removed. Thus, following excision of bowel endometriosis, we perform all necessary restoration, reconstruction and repair of the organs that have been operated on. Then, after bowel resection has been completed and the anatomy has been reconstructed, the function of the intestines must then be tested using what is called an “air leak” test (or flat tire test). During this technique, we submerge the bowels in water and methylene blue dye, then apply pressure to the area in order to push air into the intestine and ensure there is no leakage of the newly restored organs and the sutures are properly intact.

Sometimes, more extensive bowel surgery is needed. When an infected organ or area of tissue is diffusely involved, segmental resection and anastomosis may be required. This is a surgical procedure we use that cuts into the bowel in order to remove areas of diffuse endometriosis involvement, followed by subsequent reattachment of bowels to their newly restored anatomy. This could be thought of as removing and putting back together the pipes of a sink. Other versions of this include, serosal/peritoneum excision, nodulectomy and then disk excision and then segmental excision. At times we may even end up doing multi-centered surgery which involves rectal resection, sigmoid resection, ileocecal resection, and anastomosis. In other words, we can end up doing three different resection techniques with anastomosis, in order to thoroughly treat the multiple organ involvement that bowel endometriosis can cause.

What is our method of "Team Surgery?"

Endometriosis is a multiple organ disease, meaning it affects organs other than the reproductive organs, such as the bowels, rectum, appendix, etc. For this reason, we at the Seckin Endometriosis Center feel it is not just important to have the experience and skill of an endometriosis surgeon -- teamwork is necessary. We feel that bowel endometriosis surgery is very complex and deserves the best quality care, which entails a multidisciplinary surgery team.[6] In these surgeries, we thus work with a surgical team of a variety of highly skilled laparoscopic surgeons, including a GI surgeon on hand. The colorectal and urology specialists on our team have worked with us for years, and have great experience and history with working with us in the operating room. In our philosophy of “endometriosis team practice” we have a high surgical volume of diversification and knowledge, which is crucial to minimize postoperative complications and increase opportunity for a successful outcome.

How do we ensure a thorough bowel endometriosis surgery?

We also strongly believe in increasing the quality of endometriosis surgery by removing the endometriosis from every anatomical location including bowel, bladder, nerves and the ureters. While many surgeons strictly focus on the reproductive system in cases of endometriosis, we believe in conducting a thorough examination of the abdominal anatomy in its entirety, which includes the bowels. A margin-free, complete excision without leaving any disease behind is the gold standard that our team practices. It is important to not leave behind any scar tissue, as much as possible. This ensures patients to have their highest chance of recovery and symptom relief. There are also several key components and ideals we uphold in all of our endometriosis surgeries, in order to give the patient the best quality of care that they deserve. These include:

• “Deep excision”: One of the main reasons excision surgery is the most preferred method for removing endometriosis lesions is it removes each lesion in its entirety. While methods of fulguration and laser ablation not only present a risk of harming surrounding healthy tissue, they also only remove lesions superficially. In other words, endometriosis tissue that lies beneath the surface of the tissue can often times go unremoved, increasing a patient’s chances of symptoms resurfacing. “Deep excision” looks to excise each lesion out of the tissue in its entirety, while preserving the borders of the healthy tissue surrounding the lesion.
• “Cold excision”: Techniques of laser ablation and fulguration often rely on heat and electricity to destroy lesions. These are often times unnecessary uses of powerful energy sources that are associated with damaging effects on surrounding healthy tissue, while only removing lesions superficially. This is why we thoroughly believe in “cold excision,” which is excision surgery that stresses the use of minimal to no electricity in procedures, which ultimately best preserves the bodies healthy tissue.
• Pathology report: By adopting a method of excision surgery, we are able to preserve removed lesions and send them off to a pathology lab, where they will be examined by pathologist under a microscope. We feel this is a crucial component to our surgeries, as it is the best way to not only formally diagnosis endometriosis, but also gain a better understanding of its possible spreading and growth. Many other surgical methods when embraced, are unable to conduct a pathology report as they look to destroy the endometriosis tissue.
• Minimally invasive surgery: We ensure all of our patients that our surgeries, even one as complex and thorough as bowel endometriosis excision surgery, are performed with the most comprehensive care, ensuring minimal invasion. By embracing minimally invasive laparoscopic surgery for cases of bowel endometriosis, we are looking to give our patients their best chance of symptom relief and recovery.
• Experience and Skill: We at the Seckin Endometriosis Center (SEC) have been training for decades to surgically treat all sorts of different types of endometriosis cases through laparoscopy, and bowel endometriosis is no exception. Over time, we have gathered both the skill and knowledge that is highly necessary when it comes to such complex treatment options as surgical excision of bowel endometriosis.

Bowel endometriosis surgeries require a surgeon to complete such meticulously-demanding tasks as “running through” the entirety of the intestines to inspect for endometriosis lesions, to reconstructing, repairing and restoring the bowels themselves after they have been operated on. For this reason, we have learned that such a surgery does not only require great experience but also calls for a keen attention to detail. Only through meticulous surgical execution, can a surgeon remove endometriosis in the bowels. By removing these lesions, which otherwise would go undetected, we provide for our patients their highest chance of recovery and symptom relief. But the first step in order to assess bowel endometriosis and assessing if surgery is necessary is through a form of open communication with our patients.

Patient Story

As noted above, while bowel endometriosis may be prevalent in less than 20% of endometriosis cases, in our practice nearly one in every four of our patients show signs of possible bowel endometriosis. For this reason, we have a number of bowel endometriosis stories from patients that underwent bowel excision and resection surgery. Take a listen to Patrice M.’s story, in which she was rushed to the ER due to an ovarian cyst bursting in her right ovary, only to find that her endometriosis had spread to the bowels.

Read more stories of patients who had surgery for endometriosis after their disease spread to the bowels, including the rectum, appendix, and colon, in our testimony section.

References

1. Endometriosis Foundation of America https://www.endofound.org/endometriosis.
2. Seckin, T., The Doctor Will See You Now: Recognizing and Treating Endometriosis. 2016.
3. Samet, Jonathan D. et al,. Colonic Endometriosis Mimicking Colon Cancer on a Virtual Colonoscopy Study: A Potential Pitfall in Diagnosis. National Center for Biotechnology Information, November 8th, 2009.
4. B. Rizk, et al. Recurrence of endometriosis after hysterectomy. National Center for Biotechnology Information, 2014: p. 219-227.
5. Judith S. Moore., Endometriosis in patients with irritable bowel syndrome: Specific symptomatic and demographic profile, and response to the low FODMAP diet. The Australian and New Zealand Journal of Obstetrics and Gynecology, Volume 57, Issue 2 April 2017: p. 201-205.
6. Wolthuis, Albert M., et al. Bowel endometriosis: Colorectal surgeon’s perspective in a multidisciplinary surgical team. National Center for Biotechnology Information, Nov. 14, 2014.