Endometriosis and IBS are relatively common problems for women, and both can be tricky to diagnose. Symptoms are often vague such as abdominal pain, bloating, and constipation or diarrhea and may change during menstruation. It often takes years to get the right diagnosis. In cases where both are present, a diagnosis of one may mean a missed diagnosis of the other.
Here we will discuss the differences, similarities, and possible interactions between these two conditions and why it is important to get an accurate diagnosis.
What is Endometriosis?
Endometriosis is a gynecologic condition in which the tissue that forms the lining of the uterus is found outside the uterus. This misplaced tissue is often referred to as a lesion.
Lesions may stick to the lining of the abdominal cavity or other organs, including the bowel. Lesions may cause bleeding, inflammation, and formation of scar tissue. Endometriosis is associated with pelvic pain and may contribute to infertility. It can have a serious impact on a woman’s quality of life.
Symptoms of endometriosis may include1,2:
- Visceral hypersensitivity
- Chronic pelvic and back pain
- Severe period-related pain (dysmenorrhea)
- Painful ovulation
- Deep pain during or after sex
- Gastrointestinal symptoms:
- Painful bowel movements
- Constipation or diarrhea
- Urinary symptoms such as pain or blood in the urine
- Chronic fatigue
Some women with endometriosis have no symptoms.
The gold standard for diagnosis is laparoscopy. Laparoscopy is a surgical procedure where small incisions are made in the abdomen to insert a camera to view the organs and abdominal cavity. Biopsies may be taken at the same time.1
Diagnosis through laparoscopy is costly, invasive, and comes with some risk. Therefore, if a woman has suspected endometriosis, treatment may be started without a definitive diagnosis. An abdominal and pelvic exam will often be completed to support a suspected diagnosis and rule out other causes of symptoms.
Treatment for endometriosis may include one or a combination of the following: pain medications, treatments that target the nerves, hormonal therapies, and surgery.1
What is IBS?
Irritable Bowel Syndrome (IBS) is a relatively common disorder that is thought to be related to overactive gut-brain interactions 3. People with IBS have recurrent abdominal pain associated with having a bowel movement. They also typically have altered bowel habits such as constipation, diarrhea, or both. Abdominal bloating or distention is a common feature in IBS as well, though not always present.4
Symptoms of IBS may vary depending on which subtype is present (see below). However, abdominal pain must be present for a diagnosis of IBS regardless of subtype. Pain is usually associated with bowel movements.
IBS symptoms may include4:
- Visceral hypersensitivity
- Abdominal pain
- Alternating bowel habits
- Bloating or distention
- Straining during bowel movements
- A sense of urgency
- Feelings of incomplete evacuation
- Excess gas or wind
- Psychological symptoms such as anxiety or depression
Symptoms may change over time.
There is no single gold standard test for diagnosing IBS. A diagnosis is usually based on a thorough history of symptoms. Laboratory tests, colonoscopy or other procedures may be used to rule out other conditions but are not always necessary for a diagnosis of IBS.
The Rome IV criteria were developed by an international team of experts. According to these criteria, those with IBS will have symptoms of abdominal pain at least once a week (on average) for at least three months. This pain is associated with a change in stool frequency, a change in stool form, and relief or worsening of abdominal pain with having a bowel movement.3
The appearance and consistency of stool is often used to help categorize patients into the following subtypes: IBS-C (constipation), IBS-D (diarrhea), IBS-M (mixed), or IBS-U (unclassified, where a patient meets criteria for IBS but bowel habits are not consistent with other subtypes).
A relatively new blood test may be helpful in diagnosing post-infectious IBS.5 Post-infectious IBS may develop in someone who has had gastroenteritis, often caused by food poisoning. This blood test measures markers called anti-cytolethal distending toxin B (anti-CdtB) and anti-vinculin which are produced in the body in response to certain types of infection.
Treatment for IBS may include one or a combination of the following: medications to treat diarrhea or constipation, medications targeting abdominal pain, changes in eating habits, exclusion diets, fiber supplements, probiotics, herbal supplements, exercise, relaxation techniques, cognitive behavioral therapy, gut-directed hypnotherapy, and biofeedback.
Overlapping Symptoms of Endometriosis and IBS
Unfortunately, both endometriosis and IBS can be difficult to diagnose and without invasive testing it can be difficult to differentiate between the two.
In endometriosis, gut symptoms can be caused by lesions on or near the bowel. However, gut symptoms can be present without bowel involvement. In fact, in one study only about 8% of women with endometriosis had lesions that affected the bowel, whereas 90% had gastrointestinal symptoms.2
The exact mechanism for gut symptoms in endometriosis without bowel involvement is not clear. However, it may be related to inflammation, hormones, changes to the nervous system, and / or overactive gut-brain communication.
Increased visceral hypersensitivity is one of the main features of IBS and is often also present in endometriosis.6 People with increased visceral hypersensitivity are more sensitive to pressure, distention, and stimulation of the abdomen. Therefore, they may they feel pain at a lower threshold than a healthy individual.
Other overlapping symptoms of endometriosis and IBS include abdominal bloating, pain with bowel movements, constipation and / or diarrhea, nausea, and fatigue.
Misdiagnosis vs Coexisting Conditions
Given the overlapping symptoms of IBS and endometriosis it should not come as a surprise that the two conditions may be easily mistaken for one another. Many women with endometriosis are diagnosed with IBS first.
However, it is possible to have both conditions. In fact, having endometriosis may mean you are a whopping 2.5 to 5 times more likely to have IBS, according to some studies.7,8
The cause of IBS is not fully understood. There is a growing consensus that infections, such as food poisoning, are a cause of IBS in many people. However, infection does not explain 100% of cases.
Some experts argue that endometriosis may be the cause of IBS for some women. This may be related to inflammation, which has been proposed as a mechanism in the development of IBS. It has also been proposed that endometriosis may have an effect on the enteric nervous system – that is, the nerves that affect gut function.9
In many cases, IBS is diagnosed before endometriosis. If you have been diagnosed with IBS but have other symptoms that are consistent with endometriosis it is important to see a gynecologist. Getting an accurate diagnosis can assure that you are getting the proper treatment. This may be especially important for women who are trying to get pregnant.
In addition to bowel symptoms, warning signs that might point to endometriosis include painful intercourse, heavy periods, back or pelvic pain, worsening of bowel symptoms during menstruation, difficulty getting pregnant, or having a close family member who has endometriosis.
Can Diet Help Symptoms of Endometriosis?
If you do a Google search on diet for endometriosis you might find information on gluten-free, grain-free, dairy-free, soy-free, vegan, low FODMAP or any number of other diets. Evidence is lacking for most of these diets and much of the hype on the internet revolves around patient testimonials, not science.
However, in some cases reducing or eliminating certain foods might be worth considering. Avoid implementing strict diets without guidance of a healthcare professional as it could lead to nutritional deficiencies or disordered eating in certain populations.
Fortunately, some data is emerging on diets and nutrients that may be helpful for endometriosis, though evidence at this time remains weak. Given the possible connections between IBS and endometriosis, it is possible that some of the dietary strategies that are helpful for IBS may also be helpful for women with endometriosis.
For information on supplements that may be helpful for endometriosis, check out Meredith East-Powell’s blog post: 8 Supplements that help Manage Endometriosis Naturally.
Soy Free Diet
Because hormone levels are a contributing factor in endometriosis, you may come across recommendations to avoid soy. Soy contains phytoestrogens, which are plant-based compounds that are similar to the human hormone estrogen.
However, there are not a lot of human studies that investigate the impact of soy on endometriosis, and the research that is out there has mixed results. One study even concluded that soy consumption may reduce the risk of endometriosis.10
If you include soy in your diet occasionally it is not likely to cause a problem. Some women may choose to avoid having soy as their main source of protein until more research is available.
Gluten Free Diet
A gluten free diet is essential for people with Celiac disease and possibly in rare cases of non-Celiac gluten sensitivity. However, there has been a trend to eliminate gluten in the general population with many claims that a gluten free diet is superior for nearly all aspects of health. In most cases, these claims are unproven.
With endometriosis, some people do report feeling better on a gluten free diet and there is some evidence, though weak, to support it.
One study looked at the effect of a gluten free diet on relief from endometriosis related pain. In this study, 75% of participants found relief from pain while following a gluten free diet.11 This may sound promising; however, it is not clear whether the absence of gluten is truly what improved symptoms.
Gluten containing grains such as wheat, barley, and rye, are also high in fructans. Fructans are one of the five categories of FODMAPs (see below) that can trigger symptoms for people with IBS. It is difficult to determine whether the benefits seen in the mentioned study were due to the elimination of gluten vs a reduction in FODMAPs.
For those of us without Celiac disease, going gluten free can increase the risk for nutrient deficiencies, decrease overall fiber intake, and cost us more at the grocery store.
Low FODMAP Diet
The low FODMAP diet has been shown to be an effective strategy for relieving symptoms in many IBS patients. FODMAPs are a group of carbohydrate foods that are poorly absorbed and easily fermentable by gut bacteria. A low FODMAP diet is an elimination diet in which these poorly absorbable carbohydrates are removed from the diet, then systematically re-introduced.
This careful approach helps to determine which of the five categories of FODMAPs a person might be sensitive to. The goal with a low FODMAP diet is to add back as many foods as possible, while limiting the foods that cause symptoms.
One small study looked at the low FODMAP diet in women with IBS and endometriosis. In this study women with both endometriosis and IBS (vs IBS alone) were three times as likely to respond favorably to the low FODMAP diet.9
This may be important in determining who might benefit from a low FODMAP approach. Further studies are needed to determine if there is a place for the low FODMAP diet in endometriosis patients without IBS.
Healthy Fats and Antioxidants
Omega-3 fatty acids and antioxidants are nutrients of interest for endometriosis due to their potential to reduce inflammation.12 There have been some studies on these nutrients with favorable outcomes, but it may be too soon to make specific recommendations.
It is recommended to consume a well-balanced diet with an abundance of fruits, vegetables, whole grains, nuts, seeds, legumes, and healthy fats. This type of dietary pattern is associated with lower inflammation. Whereas the typical Western diet high in convenience foods, saturated fat, sugar, and sodium is associated with higher inflammation.
It should be noted that even a diet high in anti-inflammatory nutrients is no replacement for medical treatment for endometriosis. However, this type of eating pattern is encouraged for overall health and might provide some additional benefits for women suffering from endometriosis.
IBS and endometriosis are conditions that can take years to accurately diagnose. Both can cause frustrating gastrointestinal symptoms and lead to a decreased quality of life.
IBS and endometriosis are relatively common in women. In fact, IBS is more common in women than in men. This may be at least partly attributed to an increased prevalence in IBS among patients with endometriosis.
When you have gastrointestinal or gynecological symptoms it is important to get an accurate diagnosis to help guide your treatment. This will ultimately lead to improved symptom control and prevention of more serious complications.
While there is no specific diet for endometriosis, consuming a large variety of plant-based foods can help ensure that you are meeting your nutrition needs and getting anti-inflammatory nutrients. Foods to consume include antioxidant rich fruits, vegetables, whole grains, nuts, seeds, and legumes. The addition of omega-3 rich fish and seafood may also be helpful.
Those who suffer from both endometriosis and IBS may find some relief from a low FODMAP diet. However, a low FODMAP diet removes many fiber- and antioxidant-rich foods and should not be maintained long term. Working with a Registered Dietitian can help assure a low FODMAP diet is properly executed and as many foods are re-introduced as possible.
Additionally, a healthy lifestyle that includes exercise and stress management is important in IBS and in the general population. Increasing physical activity, improving mindfulness, practicing deep breathing, and recognizing stress are things we can all do to improve our physical and mental well-being.
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3. Lacy BE, Pimentel M, Brenner DM, et al. ACG Clinical Guideline: Management of Irritable Bowel Syndrome. Am J Gastroenterol. 2021;116(1):17-44. doi:10.14309/ajg.0000000000001036
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