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You vs The Entire Medical Establishment:
Bowel Endometriosis & how it can feel trying to fight for the right diagnosis.

Thanks especially to the activism of women with endometriosis, greater awareness about this potentially debilitating disease has been achieved in recent years.

Unfortunately, much work is still left to be done, as we still see patients who’ve had their bowel endometriosis in particular misdiagnosed as Irritable Bowel Syndrome (Spastic Colon), Ulcerative Colitis, Crohn’s Disease, Celiac Disease, or other more well-known gastrointestinal disorders. Many women with endometriosis have even had their severe bowel symptoms dismissively brushed off as mere indigestion.

What’s even more frustrating is that this chronic lack of awareness has been a problem endometriosis specialists have been concerned about for nearly a century – and counting. V.B. Green-Armytage, a well-regarded British gynecological surgeon of the early 20th century was particularly frustrated about the situation, noting in 1933 that, despite how common endometriosis was, he couldn’t believe that it was still only “rarely diagnosed or even thought of by the practitioners”, who instead continued to misdiagnose it as colitis, grumbling appendix, or even the long-forgotten B. Coli. Nearly three decades later, you can almost hear the same sort of exasperation from Macafee & Hardy Greer, well-known Irishs pecialists, who observed in 1960 that:

“…it is remarkable how little attention is given to this condition in most surgical textbooks, and yet in the past 30 years over 800 cases of intestinal endometriosis have been recorded.” (Macafee & Hardy Greer, Intestinal Endometriosis, British Journal of Medicine, 1960).

Diagnostic Delays Major Cause of Harm

Sadly, such longstanding diagnostic disarray does not fall into the category of harmless theoretical musings, as millions of women from around the world are the ones who end up paying the highest price and suffering needlessly each time a diagnostic error is made. In fact, multiple studies – like this recent landmark study from Johns Hopkins and this Harvard study – have identified diagnostic errors as one of the leading causes of medical harm, affecting an estimated 12 million Americans each year and accounting for up to 17% of preventable hospital medical errors.

For all of these reasons, we decided it was time to provide an updated literature review article on bowel endometriosis (also called intestinal endometriosis), which can be one of the most serious forms of what is already a potentially life-altering disease. Through these sorts of continued awareness efforts, we hope to empower those who are most affected with the most accurate, up-to-date information, with the goal of one day making unacceptably long diagnostic delays a thing of the past.

Before getting into the details, we thought it would be a good idea to first address the equally longstanding confusion concerning the estimated incidence risk rate of bowel endometriosis, which, incredibly, has remained almost as imprecise as it was generations ago.

First things first: How Common is Bowel Endometriosis?

Though it’s not clear who was the very first to report on bowel endometriosis, one of the earliest studies of the 20th century was published in 1908 by Robert Meyer. Yet, despite more than a century of research on the subject since Meyer’s work, in many ways we are still no closer to understanding bowel endometriosis than we were back then.

Even basic questions concerning disease frequency still cannot be answered with any great authority. For example, if you keep up with endometriosis medical literature, you’ve probably noticed that the unusually broad range of 3-37% is often cited as the estimated risk rate of bowel endometriosis.

Estimated risk rates are supposed to become more precise in lockstep with improved diagnostic technologies and awareness efforts. And yet, if you review older medical literature on the subject, you find that the estimate range has barely budged in decades.  One article from 1960 is particularly revealing on this point, as it cites a nearly identical risk rate of 3%-34%, based on a meta-analysis of 7,000 endometriosis cases reported between the years of 1913-1960. (Macafee & Greer, Intestinal Endometriosis, British Journal of Medicine, 1960).

Either Rain or Shine

Unfortunately, overly broad estimates like these are about as useful as a weather report that says it’s either going to rain or be sunny! In other words, they’re essentially just too imprecise to be of any use in a clinically setting.

Of course, we could just quickly settle the matter by assuming that the average of these figures – 20.4% – would be as good a guess as any. However, as certified data nerds over here, imprecision like this was bothering us just as much as it was probably bothering you! And so, we decided to dive in a little deeper, to see if we could provide more insight into such a basic question as the disease frequency of bowel endometriosis in women with endometriosis and whether it’s as rare as some of the lower-range estimates would suggest.

Most Common Form of Extragenital Endo? Bowel Endo

To simplify things, we’ll set aside the question of prevalence rate in the general population, which is a different measurement. Instead we’ll limit the analysis to just the incidence risk rate (also called incidence proportion rate) of bowel involvement in the population at risk for developing the disease; namely, the estimated 10% of the (usually reproductive-aged) female population who develop endometriosis. In other words, we will try to answer the question that women with endometriosis would likely ask:

“What is the chance that I’ll develop bowel endometriosis?”

With the question narrowed in this specific way, we start to get more useful data, at least from a clinical standpoint instead of an epidemiological one. One intriguing finding is that today bowel endometriosis is recognized as the most common form of extragenital endometriosis, accounting for approximately 80% of all cases of endometriosis that doesn’t involve a woman’s reproductive organs or structures.

Selection Bias Skewing Estimates

Such statistics are interesting, but they still don’t really answer the burning question: just how common is bowel involvement in women with endometriosis?  An exact number can never really be known, due to a variety of factors.

However, one thing we do know is that the commonly cited statistics on the matter are riddled senseless with selection bias. In fact, as epidemiologists would be quick to point out, aggregating data from disparate studies (like what is done for meta-analyses) can easily lead to very misleading conclusions if done incorrectly; Indeed, even outright alternative Franken-facts can result if researchers commit the ultimate epidemiological sacrilege of failing to follow established guidelines, like the ones outlined in the PRISMA standards for systematic reviews.

This means that the numbers at both ends of the large estimate range should be qualified and understood as confounded by selection bias, as well as other potential study design flaws. In the case of the lower range estimates like 3%, such calculations may be based on years of under-reporting by non-specialists, who naturally tend to see fewer endometriosis patients, which translates into predictably lower reported incidence risk rates. (Of course, this is setting aside the issue of spurious results from mixing prevalence and incidence data).

In 14 years, for example, one colorectal surgeon reported encountering only26 cases of endometriosis of the bowel. Contrast this to a referral center like Drs. Nezhats, where 26%-30% of endometriosis patients are found to have histopathologically confirmed bowel involvement.

Unfortunately, under-reporting by non-specialists has likely contributed to the persistent myth within the medical community in general that bowel endometriosis is extremely rare. Yet, historically, even specialists admitted missing certain types of endometriosis in the days before video laparoscopy became the diagnostic and surgical gold standard. One study, for example, noted that the diagnosis of endometriosis at surgery increased from 42% in 1982 to 72% in 1988, reflecting the switch from open surgery to video laparoscopy in the late 1980s. And bowel endometriosis was one of the types of disease that was particularly susceptible to being missed during open surgery, with one specialist noting that “The deep cul-de-sac including anterior rectum and posterior vagina was largely neglected” in the days before video laparoscopy. Despite reports like these, which demonstrate a history of diagnostic errors even by specialists, nevertheless old beliefs can sometimes have a long shelf life in medicine.

It’s no wonder, then, that so many women still continue to be misdiagnosed when they report bowel symptoms that a specialist would recognize as possibly suggestive of bowel endometriosis, but which specialists from other disciplines might indeed mistake for other diseases with similar symptoms. As mentioned, such diagnostic errors are far from harmless and have even led to unnecessary surgeries, like this case of a woman losing her perfectly healthy appendix because her ileum endo was mistaken for acute appendicitis; or like the especially heartbreaking cases when unnecessary colostomies are performed or several inches of healthy bowel are removed because bowel endo was mistaken for cancer.

Bowel Endo Not So Rare

Although we’ll never be able to completely extricate ourselves from the clutches of selection bias or other potentially confounding factors, the good news is that recent reports from non-specialists are showing signs that the old myth about bowel endometriosis being extremely rare is finally coming to an end. In one gastroenterology article from 2012, for example, the author emphasizes this point in his first sentence, stating unequivocally that

Endometriosis of the gastrointestinal tract is a common disorder.”

Another non-specialist reported in 2005 that, although he only saw 29 patients with endometriosis in 8 years, of those 24% (7/29) had bowel endometriosis that was severe enough to warrant surgical intervention.

Indeed, as even non-specialists might now agree, it does seem fairly clear today that bowel involvement in endometriosis patients is not as rare as the lower, single digit estimates like 3% would suggest.

Even early 20th century specialists began to suspect this. In 1918, for example, British surgeon Prof. Dr. Cuthbert Lockyer, one of the world’s most respected endometriosis experts at the time, noted that the “medical literature concerning adenomyomas of the alimentary tract was quite extensive,” while in the same year legendary endometriosis specialist, Thomas Cullen, described rectovaginal septum bowel disease as especially “widespread”, as if he were trying to convince his skeptical colleagues otherwise. (Lockyer’s Fibroids and Allied Tumors, 1918).

As for updated estimates from today, based on the latest research, and taking into consideration the issues of selection bias, publication bias, and other potential study design flaws, the disease frequency of bowel endometriosis may indeed be in the double digits after all, possibly somewhere between 15-20%.

However, we’ll need to review more clues to help unravel this century’s long enigma.


Advanced Disease Predictor of Bowel Involvement

Additional evidence suggesting that bowel involvement is likely more common than initially believed can be inferred by its correlation with other forms of endometriosis, for which we have better statistics. As it turns out, bowel endometriosis has been found to be more common in those with moderate to severe, Stage III-Stage IV disease. Deeply infiltrating endometriosis (DIE) is also now considered by most experts as a form of severe disease, so this means its presence is predictive of potential bowel involvement as well.

You might now be thinking, ‘But how common is moderate to severe endometriosis?’ Studies vary greatly, but recent estimates suggest that up to 41%of women developmoderate to severe disease. As for the most aggressive deeply infiltrating endometriosis, a 2016 study by Lagana et al, reported that it occurs in “approximately 20% of all women with endometriosis.” Of course, referral centers normally will report higher figures than these. For example, in one of Dr. Nezhat’s studies, 61% of the study participants had the most severe, stage IV disease.

Another way to look at this question is to consider that endometriosis is the leading cause of hysterectomy and third leading cause of gynecologic hospitalization in the U.S. Therefore, no matter what is said, about this or that stage, disturbing statistics like these speak volumes and demonstrate just how serious endometriosis can be for a very large number of women.

Ovarian Endometriosis Also Predictor of Bowel Disease

Studies have also shown that those with ovarian endometriosis are more likely to have bowel involvement as well. Even specialists from nearly a century ago noticed this pattern, including the father of endometriosis himself, John A. Sampson, who reported in 1922 that bowel involvement occurred in 50% of his patients who had ovarian endometriosis.

Since the ovaries are considered among the most common sites of endometriosis, representing up to 50—80% of all cases, this is another indicator suggesting that bowel involvement is not especially rare by any means.  New research conducted by Dr. Nezhat et al also found that 62% of those with bowel endometriosis had urinary tract involvement as well (bladder and/or ureter).

Risk Factors Predictive for Bowel Endometriosis

  • Presence of moderate to severe disease
  • Presence of Ovarian Endometriosis (Endometriomas)
  • Presence of deeply infiltrating endometriosis (DIE)
  • Presence of rectovaginal septum endometriosis (RSE)
  • Presence of urinary tract endometriosis (bladder/ureter)
  • Previous surgeries for endometriosis

Most common sites? Rectum & Sigmoid Colon

Considering that the entire intestinal tract can average up to 30 feet long if it were to be fully stretched out, this means that there are potentially up to 30 feet worth of areas where bowel endometriosis can grow, since the disease has proven itself a master of survival in nearly every anatomical areaof the body (except the spleen apparently). However, endometriosis seems to have a preference for certain areas more than others, a pattern that was also observed by early 20th century specialists.

In fact, endometriosis’ propensity for anatomical favoritismis so pronounced, that an estimated 72%-93% of cases occur in just two specific sites of the bowel:

  • Rectum
  • Sigmoid Colon

These observations aren’t actually new discoveries. Nearly 100 years ago, legendary specialists like Cullen and Lockyer also repeatedly observed these disease patterns.

Anatomy class, revisited

As you can may recall from anatomy class (see Figure 1 and 2), the rectum is the straight-yet-a-little-twisted section of the lower large intestine, measuring in at about 18-20 centimeters (cm) long (~7 inches) and 2.5–3 centimeter in diameter (~1 inch). The rectum is wedged between the anal canal at one end, the sigmoid colon on the other, and the rectovaginal septum at its front (anterior), which separates the rectum from the posterior vaginal wall. As you can see from Figure 3, the deepest part of the pouch of Douglas (posterior cul-de-sac, rectouterine pouch) is also adjacent to the rectum, where it serves as a membranous partition between the top half of the rectum and the uterus. Although a multi-tasker, playing a key role in water and electrolyte resorption, the rectum’s main function is to store feces until the brain tells the body that it’s time to go.

Is there something about the rectum – especially its anterior wall – that makes endometriosis want to grow there? Many endometriosis hotspots are in close proximity to the rectum, including the ovaries, the uterosacral ligaments, posterior vaginal fornix, and rectovaginal septum.

In fact, rectovaginal septum endometriosis (RVE) has long been recognized as one of the areas most often associated with severe disease, including obliterated cul-de-sac and deeply infiltrating endometriosis (DIE), one of the most potentially painful and aggressive forms of endometriosis, known for its ability to aggressively invade adjacent tissue, accompanied as well by severe fibrosis and densely packed tentacles of scar tissue engulfing practically everything in its path.

By the early 20th century, specialists had also zeroed in on the rectovaginal septum as an especially active area of especially aggressive disease. In 1920 Schwartz even suggested that the deeply infiltrating rectovaginal growths nodules he kept finding – referred to back then as adenomyoma of the rectovaginal septum – were the likely source that would eventually progress and invade the rectum and sigmoid colon. “The rectal mucosa at first moves freely over the adenomyoma [of the rectovaginal septum]” Schwartz noted, but that eventually it becomes “blended with the adjacent anterior rectal wall.”

But, why the rectum and its upstairs neighbor, the sigmoid colon, but not its distal downstairs neighbor, the anal canal? And what about the extraperitoneal vs. intraperitoneal parts of the rectum, do these different areas show different disease patterns? Such seemingly simple questions, yet no one actually knows the answers! For our detail-loving viewers, stay tuned for an upcoming segment about these enigmas, including information about possible connections between the rectum-sigmoid colon and other tissues in the body that endometriosis seems to prefer.

Other common areas of bowel endo
After the rectum and sigmoid colon, the other most common sites have been reported as follows:

  • Rectovaginal Septum (about 57%)
  • Appendix (about 24%)
  • Ileum (distal ileum, ileocaecal region)(about 5%)
  • Cecum (about 3.5%)

There is essentially universal agreement that the rectum and sigmoid colon are the most common sites of bowel endometriosis. However, when it comes to the next most common areas, studies do vary, with some suggesting that one or the other is more common, and vice versa. (Frequency estimates of appendix endo are particularly controversial, with some insisting that it’s one of the most rarest sites, while others think it’s more common than reports would indicate). It’s also important to note that more than one area of the bowel may be affected, with some reports suggesting that up to 30% of cases involve multiple sites. For this reason especially, there is a great deal of overlap in the above-listed reported percentages.

Rare cases of other parts of the large intestine have been reported in the literature and include:

  • Transverse colon
  • Descending colon
  • Gallbladder
  • Hepatic Juncture
Most Common Sites of Bowel Endo
* Rectum & Sigmoid Colon
* Rectovaginal Septum
* Appendix
* Ileum
* Cecum

Small Intestine
With the exception of the ileum (which is part of the small bowel), small intestine involvement is more rare, accounting for only about 7% of cases of bowel endometriosis (a figure which likely corresponds to just the ileum). As for other areas besides the ileum, there are so few cases in the medical literature, that you can practically count them on just two hands, including such rare forms as:

  • Meckel’s Diverticulum
  • Jejunum
  • Duodenum

Even though these cases of small intestine endometriosis are now considered certifiably rare, no area of the body should ever be ruled out when it comes to endometriosis, which continues to defy our clinical gaze with its uncanny abilities of self-preservation and chameleon-esque tendencies, which have earned it the undisputed title, the great masquerader.


Symptoms of Bowel Endometriosis
Given the wide variety of often paradoxical symptoms, including asymptomatic cases, the nickname of ‘great masquerader’ definitely seems like an appropriate title for this particularly difficult to diagnose disease.And when all tests come back normal, like is so common with endometriosis of any kind, this makes the situation all the more stressful, as women are sometimes accused of imagining or faking their symptoms if tests fail to detect any abnormalities.

This is why we really provide as much extra detail in this symptoms section as possible, to help raise the index of suspicion, especially for those who may not experience classic disease patterns or symptoms.

Symptoms of bowel endometriosis can include:

  • Abdominal or intestinal (stomach) “cramping” or pain
  • Painful bowel movements (dyschezia)
  • Constipation
  • Diarrhea
  • Alternating Diarrhea and Constipation
  • Abdominal Bloating (Abdominal distension)
  • Overall change in bowel habits, including hyperperistalsis, flatulence
  • Cyclic Bowel symptoms associated with menstruation
  • Bowel urgency or incomplete evacuation of bowels
  • Nausea and/or vomiting, often with menstruation
  • “Cramping” rectal pain (tenesmus)
  • Rectal pain when sitting
  • Changes in the color or consistency of stool
  • Painful sexual intercourse (dyspareunia)
  • Bladder symptoms, especially urinary frequency
  • Sub-fertility and/or Infertility
  • Cyclic and/or chronic hematochezia
  • Cyclic and/or chronic epigastric pain
  • Blood in the stool
  • Bleeding within the intestinal tract (enterorrhagia)
  • Acute right-side pain that mimics appendicitis
  • Bowel symptoms that mimic Ulcerative Colitis
  • Bowel symptoms that mimic Crohn’s Disease
  • Bowel symptoms that mimic other Inflammatory Disease
  • Bowel symptoms that mimic Irritable Bowel Syndrome
  • Bowel symptoms that mimic Celiac Disease

Symptoms that require urgent medical care
Although extremely rare, life-threatening cases of bowel obstruction and/or perforation caused by bowel endometriosis have been reported in the literature and would require urgent emergency surgery to treat. Some reports estimate that only about 1% of bowel endometriosis leads to true bowel obstruction. The number of cases of bowel perforation caused by bowel endometriosis are less clear, but one study suggested the rate to be 1 in 1500 cases.

Even though such cases are exceedingly rare, it’s always a good idea to be aware of potentially serious clinical symptoms, which includes:

  • Extreme flu-like symptoms
  • Fever, chills, clammy wet skin
  • Other sepsis symptoms like rapid breathing & extreme drop in blood pressure
  • Feculent vomiting (fecal vomiting)
  • Extreme abdominal distention
  • Blood in stool
  • Severe diarrhea causing dangerous dehydration
  • Severe constipation that goes on for longer than several days

Symptoms:Caveats & Contradictions
When it comes to endometriosis, so many exceptions and contradictions apply that lengthy qualifying statements are almost always needed, even for something that seems so straightforward as a list of symptoms. But, given the complexities involved, we thought you’d appreciate the following additional details that will help provide more perspective and context when it comes to the often unusual proclivities of bowel endometriosis symptomology.

Superficial or Severe Disease?
To begin with, one important point to remember about bowel involvement is that it can run the gamut from mild, superficial lesions that appear to cause no troublesome symptoms, to severe, full thickness disease that is so destructive that parts of the bowel become completely destroyed, damaged beyond repair, resulting in the sufferer enduring major reconstructive surgery in order to restore normal organ function, a process that may entail losing significant segments of one of the body’s most important organs. As a result of such a wide range of potential disease tendencies, naturally symptoms will vary, as well as treatment protocols, depending on the severity of disease. Bowel endometriosis may also be a progressive disease, meaning that symptoms may worsen over time.

Women can also have bowel endometriosis and other bowel disorders like colitis at the same time (co-morbidities), which can sometimes throw a clinician off the correct diagnostic trail initially.

It’s also important to bear in mind that medications commonly prescribed for endometriosis, like GnRh analogs, other hormonal treatments, and opioids, can also cause or exacerbate existing bowel symptoms, which may further complicate attempts to accurately diagnose the true underlying cause of the various symptoms.

Bowel symptoms but no bowel disease
However, what complicates matters even more is the fact that gastrointestinal (GI) symptoms are “almost as common as gynecological” ones. [3 ) Some studies even suggest that up to 90% of all women with endometriosisreport bowel symptoms, but only a fraction of those end up being diagnosed with bowel endometriosis at surgery.

Bowel disease but no bowel symptoms
In a paradoxical twist to the dilemma of bowel symptoms without bowel disease, studies also show the opposite; that many women with histopathologically confirmed bowel endometriosis often do not report any bowel symptoms! For example, in a study by Nezhat et al, of those with histopathologically confirmed bowel endometriosis, 41% reported having no bowel symptoms at all. Of the remaining 59% of patients who did report GI symptoms, only 36%included those symptoms as one of their chief complaints.This is similar to the symptom profile of other types of endometriosis, where women may only have mild or no symptoms at all, yet have extensive disease – and vice versa.

Menstruation and symptoms not always in sync
Perhaps even worse still, studies dating back decades have consistently shown that many women with symptomatic bowel endometriosis also do not experience the classic cyclical onset of symptoms, which is one of the most universally recognized hallmarks of endometriosis. According to the same study by Nezhat et al, only 45% of patients described their symptoms as cyclic in nature, occurring at or around the time of menstruation. This means that the majority – 55% – did not have symptoms that correlated to menstruation.

Such statistics won’t be surprising to specialist or women with endometriosis, who already know that symptoms don’t always follow classic disease patterns. Unfortunately, this common absence of any discernible cyclic correlation with menstruation is likely another reason that bowel endometriosis is so easily missed by non-specialists. Indeed, non-specialist gynecologistswill likely take one look at all of the GI symptoms being reported and will end up referring women to gastroenterologists.This may represent the first of many fateful wrong turns and diagnostic dead ends that women may face for years, because,once at the gastroenterologist’s office, they too may take one look at all of the apparent heterogeneous symptom chaos and end up labeling what they see with the medical equivalent of a junk drawer diagnosis, such as Irritable Bowel Syndrome or other similarly non-specific ailments.

Even though all of these diagnostic hurdles may seem daunting at first, there is hope, as upon closer inspection, definite clinical patterns are discernible which can help a doctor potentially recognize signs of bowel endometriosis during an initial diagnostic workup, which we cover in the diagnostic protocols section of this page.  As noted earlier, many of the disease patterns listed above have also been consistently observed for nearly a century, which is an excellent indicator that these diagnostic clues are likely to be clinically significant.

Impact of Bowel Endometriosis? Potentially Devastating

Bowel endometriosis: a life-altering disease
Even though symptoms lists and overviews can be useful for providing a snapshot of a disease, what they cannot tell you is just how unbearable and severe these symptoms can be, especially for the person who is suffering from them several times a month, or even daily. Take the symptom of constipation, for example. Did you know that women with endo have reported constipation that lasts for up to several weeks? Imagine how much extreme discomfort and sickness this can cause! As for abdominal bloating – ‘endo belly’ as it is called in the endometriosis community – it can be so severe, that women with this symptom may bemistaken as being 6-9 months pregnant. Severe abdominal swelling can also cause tremendous discomfort and other life-altering symptoms, such as bladder incontinence.

The severe, chronic diarrhea that may accompany bowel endometriosis can be equally grueling.  As one article noted about a rare case of Meckel’s Diverticulum endometriosis, the patient experienced severe diarrhea that occurred over 8 times a day. Serious cases of diarrhea like this can cause severe dehydration and sickness that could require urgent medical attention.

Women with bowel endometriosis can also lose a lot of weight due to severe pain associated with eating. One patient lost 60 pounds in just a few months period because her bowel endometriosis caused so much acute sudden pain the moment she ate.

And bowel movements – well, as one patient described it, they were simply unbearable. In fact, many women with severe bowel pain have described passing out right there in the bathroom – public bathrooms included – because the pain was so excruciating. Pain so severe patient can barely breathe.

As for sexual intercourse, it is also described by many with bowel endometriosis in particular (or closely related – rectovaginal septum disease) as just “out of the question”because the pain is so excruciating. This symptom alone can put a lot of strain on relationships and cause extreme emotional distress to couples.

Violent, contracting pains
Specialists from the early 20th century were very sympathetic to the terrible suffering that bowel endometriosis could cause in their patients.For example, a specialist from 1939 described one of his patients with bowel endometriosis as suffering horribly with “violent, contracting pains in the abdomen” that were so painful that the woman was in a state of abject fear each time her next period approached. Back then, specialists were even referring to invasive bowel endometriosis as “strangulating intestinal endometriosis”, which no doubt better describes the type of extreme symptoms this form of the disease can cause.

Misdiagnoses leads to wrong treatments
As for bowel endometriosis’ ability to mimic other diseases, this too is a serious matter that can potentially lead to unnecessary risks, including harm caused by unnecessary surgeries. The case of unnecessary emergency appendectomies is particularly telling on this point. Referred to as “negative appendectomy”, these are cases of unnecessary surgery, when a healthy appendix is mistaken removed from patients in an emergency setting who were misdiagnosed with acute appendicitis. The error rates are incredibly high in women especially, with studies showing unnecessary removal of healthy appendix occurring in approximately 20-30%.

As you can probably guess, women with undiagnosed endometriosis are even more susceptible to these types of surgical misdiagnoses in emergency settings, as their acute right-side pain symptoms can easily be mistaken for burst appendix, when in fact they may have bowel endometriosis of the ileum or a right-side burst ovarian endometrioma, both of which can present with similar symptoms.

Many emergency surgeries are done via the more painful and potentially riskier large-incision laparotomies. This means that women with endometriosis have likely been needlessly subjected to the potential serious risks of major surgery for decades (losing their healthy appendix to boot) despite the fact that nearly 100 years-worth of medical literature exists which has been repeatedly warning practitioners about bowel endometriosis’s uncanny ability to mimic acute appendicitis.

Thankfully, recent studies suggest that these high error rates havebeen declining over the last 10 years, a welcome trend emergency room surgeons attribute in part to theirnew custom of utilizing diagnostic video laparoscopy before surgery, which has helpedsignificantly reduce the rate of unnecessary appendectomies.

Though any unnecessary surgery is a terrible thing, there are actually even worse cases than negative appendectomy that women with endometriosis have been subjected to over the years. The stories of extremely risky and ghastly abdominoperineal procedures and permanent colostomies for presumed cases of bowel cancer are some of the most heartbreaking. Referred to as “mutilative operations” by one mid-20th century specialist, these tragic errors were the result of women with endometriosis mistakenly subjected to extremely dangerous radical surgeries intended for bowel cancer, which can be nearly indistinguishable to the naked eye from bowel endometriosis.

Even modern practitioners today often mistake bowel endometriosis for adenocarcinoma in particular, which is an especially aggressive cancerthat can appear to the naked eye nearly identical to certain cases of advanced bowel endometriosis, even to trained oncologists!

Thanks to the modern technique of intraoperative frozen section histopathological inspection, today many are saved from making the same mistakes as countless others used to do in the not-too-distant past. However, there are a few very recent reports that give reason for pause, which make us realize that we are not out of the danger zone yet on this issue. The most recent of these very unfortunate cases was from 2016 in which the anguished author admits to having made the grave error of removing a large segment of his patient’s bowel, thinking it was a case of bowel cancer, only to find later that the diagnosis was bowel endometriosis of the ileum.

Another error involving removal of several inches of bowel was reported in a 2009 gastroenterology journal, in which the author was so sure that the tumor on the vermiform appendix was cancer that a frozen section to double check wasn’t done.Instead, not only was the appendix where the tumor was found removed, but also the “cecum, ascending colon, terminal ileum, and 16 lymph nodes were performed under the clinical diagnosis of gastrointestinal stromal tumor.”Prior to surgery, a colonoscopy had been performed, during which time two repeat biopsies were done, but in both times, they failed to show signs of endometriosis.

Even in such rare cases when errors like these are made, at least surgeons now try to avoid open surgeries as much as possible, thanks to the advent and acceptance of video laparoscopy,which ushered in the modern era of minimally invasive surgery and influenced surgeons from all disciplines, including oncology, to move away from the radical large incisions surgeries of yesteryear. In fact the transformation to minimally invasive surgery has been so successful that many gynecological surgeons today have never even witnessed the radical operations of yesteryear, such as midline, abdominoperineal, McBurney incision for open appendectomy,or other extremely large-incision open surgeries that not too long ago were once so common.


– Diagnosing Bowel Endometriosis: Common Diagnostic Errors

– Diagnosing Bowel Endometriosis: Step-by-Step Workup

– Treating Bowel Endometriosis

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