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Bowel Endometriosis

It can be safely excised!

In spite of some inexperienced doctors saying that bowel endometriosis is too “risky” to be removed, the truth is that in the hands of an actual expert excision surgeon who has extensive experience with bowel endometriosis, it can be fully excised with a very low risk of complication! When a doctor says that it’s “too risky” to remove bowel endometriosis, it usually means that they lack the skills need to safely remove bowel endometriosis. And of course if they don’t have the skills, we wouldn’t want them to operate there because there could be complications, so if a doctor says treating bowel endometriosis is too risky, that’s a red flag to seek another excision surgeon.

Unfortunately, some doctors who lack experience in endometriosis treat bowel endometriosis as if it were cancer and unnecessarily remove feet of intestines or give the patient a colostomy. Bowel endometriosis is typically treatable without the need for either of this, and the lesions can be treated by shaving, discoid resection, or segmental resection. Which surgical method the doctor uses depends on the lesions themselves, such as their location and depth on the bowel.

Can imaging detect bowel endometriosis?

Ultrasound and MRI

Ultrasound and MRI may detect signs of bowel endometriosis, especially if it’s deeply infiltrating or has distorted your pelvic anatomy. How the scans are done, the machine used, and the expertise of who is reading the scans is extremely important.

Most gynecologists are doing routine trans vaginal ultrasounds instead of expert-guided trans vaginal ultrasounds (ETVUS) for endometriosis. A routine ultrasound typically is quick and focused on the ovaries/uterus, while an ETVUS takes the time to systematically look at the other organs in the pelvic cavity like the bowel, bladder, as well as at the relationship/movement between the pelvic organs to pick up signs of endo. This is why many skilled excision surgeons read their own ultrasound or MRI scans, or they work with someone who is an expert in doing scans for endometriosis. MRI might be more accurate for higher lesions on the sigmoid, the right colon, and small bowel.

Keep in mind though that a negative scan doesn’t mean you don’t have endometriosis or bowel endometriosis. Also, just because someone calls their ultrasound “expert-guided” doesn’t mean that it actually is.


Bowel endometriosis isn’t usually seen on a colonoscopy. Your bowel has 4 layers (from outside to inside): serosa, muscularis, submucosa, and mucosa. Endometriosis lesions are typically found on the outer layers of the bowel. In fact, one study from 2015 found that only 2.6% of intestinal endometriosis in 76 patients was on the innermost layer of the bowel. Since a colonoscopy is a camera that looks inside your intestines but doesn’t see the outside, it typically doesn’t pick up endometriosis as it’s not very common for endometriosis to invade through the 4 layers of the bowel. That same study found that colonoscopy failed to detect endometriosis in 70 of 76 (92.1%) patients with intestinal endometriosis. Considering that a colonoscopy is invasive, and often expensive, and really doesn’t pick up endometriosis, it’s not a good diagnostic test for endometriosis.

Bowel symptoms don’t mean you have bowel endometriosis

It’s hard to know the exact number of people with bowel endometriosis.  but I’ve seen some estimates put it at 15-20% (in the literature the range is from 3-37% (Ferrero, 2011)). In specialized practices for endometriosis, such as centers for endometriosis, the percentage of patients with bowel endometriosis can be much higher, like around 30%.

An even higher percentage of people with endometriosis, up to 90%, present with digestive problems such as diarrhea, constipation, alternating diarrhea and constipation, painful bowel movements, intestinal cramping, and severe bloating (aka the beloved endobelly). Not all of these people have bowel endometriosis, and endometriosis doesn’t have to be located on the bowel to cause digestive symptoms. Things like inflammation, prostaglandins, pelvic floor dysfunction, SIBO, adhesions, food intolerances, and other reasons directly or indirectly related to endometriosis can cause bowel symptoms.

Questions to ask your surgeon

In addition to the 3 sets of questions to ask your surgeon on my page on How to Find a Specialist, if you or your doctor suspect you have bowel endometriosis, you can ask additional questions to gauge their skills excising bowel endometriosis:

Are they prepared to fully excise bowel endometriosis?

Answer should be yes. They shouldn’t leave endometriosis behind “when it’s too risky” (this typically means they lack the skills to operate on it). They shouldn’t leave it behind because they didn’t go adequate surgical planning and didn’t have a GI surgeon on standby or didn’t have the patient do a bowel prep.

Do they work with a colorectal or gastrointestinal surgeon? Does that surgeon have experience with bowel endometriosis?

Many excision surgeons will work with a colorectal or GI surgeon for bowel endometriosis. If they do, it’s important that the other surgeon is familiar with removing bowel endometriosis, because excision surgery is not the same as surgery for colitis or cancer. If they don’t work with another surgeon, why not? For example, do they operate on the bowel endometriosis themselves? If so, are they prepared to do an extensive case of bowel endometriosis by themselves?

How many cases of bowel endometriosis do they do a week/year?

Most experts do excision surgeries multiple times a week and see bowel endometriosis among some of those cases. It’s important that the surgeon have a high volume of excision surgeries which include bowel cases because doing excision just a few times a month isn’t enough to give them the skills they need. In specialized practices for endometriosis, such as centers for endometriosis, the percentage of patients with bowel endometriosis is typically higher than among the general endometriosis population, and may be around 20-30%.

Will they have you do a bowel prep so your bowel will be prepared in case they find bowel endometriosis so you don’t have to do another surgery?

Many surgeons have the patient prepare for bowel surgery using a bowel prep, although there are some that prefer the patient have solid stools. The point with this question is that the surgeon get you and your bowel prepared for bowel surgery. Because if they require a bowel prep to operate on bowel endometriosis, and they don’t have you do one but they find bowel endometriosis, then they may not operate on your bowel endometriosis since your bowel wasn’t prepped – this likely means you’ll need to excise your bowel endometriosis in a second surgery.

What techniques do they use to excise bowel endometriosis and how do they decide which one to use?

Techniques include shaving, discoid resection, and bowel resection. Which one they do depends on the location and depth of the bowel endometriosis. There is a logic behind the surgeon choosing which technique to use and there’s more info in the “Understanding Bowel Endometriosis” link of the resources below.

What’s their personal rate of complication? What’s their rate of colostomy, as in, how many of their patients need a colostomy bag?

Their complication rates should be very very low, like under 5%. For a colostomy, it should be almost never, as endometriosis generally can be safely removed from the bowel without needing a colostomy bag. Here’s a quote from Dr Ken Sinvero about his complication rates with bowel resection:

“The risk of serious post-operative complications occur less than 5% of the time. The risk of long-term complications are rare, and the most serious being stenosis or narrowing of the bowel at the re-anastamosis site (where the bowel was reconnected after the bowel resection). The risk of colostomy is less than 1-4%, depending on where the bowel resection was performed, and we have never had a permanent colostomy. Sometimes, colostomy is needed if the bowel resection was very low (less than 7-8 cm from the anal verge).”

You can use these rates as an idea of how low complication rates can be in the hands of a true expert, but remember you need to find out what your surgeon’s complication rates are because they vary from surgeon to surgeon depending on their skill and experience.

What kind of pre-operative planning will they do so that they are prepared when they operate?

Most excision surgeons will do an ultrasound and possibly an MRI so they have a better idea of your endometriosis and what they will encounter when they operate. Remember that colonscopy doesn’t typically detect bowel endometriosis since 90-95% of bowel endometriosis doesn’t go through the 4 layers of the bowel.

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