SIBO and Pelvic Pain

9 minutes

According to the International Pelvic Pain Society, chronic pelvic pain (CPP) negatively affects millions of people across the gender identity spectrum throughout the world. 

It can impact a person’s physical, emotional, social and material well-being. There are many biopsychosocial contributors to pelvic pain and healthcare providers need special skills in physical examination and history taking in order to better evaluate and treat patients with this type of pain. Often, conventional medical and surgical treatments are ineffective, however, a range of new medical, surgical and mind-body therapies are available to help improve the lives of individuals living with CPP.

Because there are many causes of pelvic pain, it is challenging to determine the causative factors. Pelvic pain can be a result of various gynecological conditions, from sexually transmitted diseases to cancer treatment side effects and pelvic abnormalities. There is one often-overlooked condition that causes pelvic pain: SIBO.

Small intestinal bacterial overgrowth (SIBO) occurs when there is an abnormal increase in the overall bacterial population in the small intestine, particularly types of bacteria not commonly found in that part of the digestive tract. This condition is sometimes referred to as blind loop syndrome. It is associated with a broad range of predisposing small intestinal motility disorders and with surgical procedures that result in bowel stasis. What is unique about SIBO is that there are excessive numbers of aerobic and anaerobic bacteria colonizing the small intestine, a region usually containing few bacterial populations. The bacteria typically recognized as SIBO are mainly of the colonic type and are thus predominantly gram-negative aerobes and anaerobic species that ferment carbohydrates into gas. Common bacteria found in SIBO include Escherichia coli, Enterococcus spp., Klebsiella pneumonia and Proteus mirabilis, among others. The SIBO hypothesis proposes that it is this expansion of bacteria into the small intestine from the large intestine that leads to symptoms including bloating, abdominal discomfort and changes in stool form.

The true prevalence of SIBO and its relationship to various disorders is largely unknown. It is particularly difficult to define its true prevalence because there is an association between SIBO and a number of other disorders and symptoms often overlap. Bacterial overgrowth may be asymptomatic or only present with nonspecific symptoms, and all symptoms might be incorrectly ascribed to the underlying disease (leading to SIBO). In addition, the prevalence of SIBO is directly dependent on the characteristic of the study population and the diagnostic method used to detect or define bacterial overgrowth. If a breath test is used as the diagnostic method, prevalence varies further depending on the nature and dose of substrate used. In healthy people, SIBO has been described in 0–12.5% by the glucose breath test, 20–22% by the lactulose breath test and 0–35% by the 14C d-xylose breath test. Elderly patients may be especially susceptible to SIBO because of both a lack of gastric acid and the consumption of a disproportionately large number of drugs that can cause hypomotility. In addition, depending on the disease or disorder, the literature on the prevalence of SIBO varies substantially. For instance, the prevalence of SIBO in IBS varies from 30 to 85% depending on the source used. The prevalence of SIBO in liver cirrhosis is 50% and in celiac disease, the prevalence of SIBO in some studies is also estimated to be 50%. Interestingly, in asymptomatic morbidly obese patience the prevalence of SIBO was noted to be 17%.

Signs and symptoms of SIBO often include:

  • Loss of appetite
  • Abdominal pain
  • Nausea
  • An uncomfortable feeling of fullness after eating
  • Unintentional weight loss
  • Malnutrition
  • Abdominal bloating one to two hours after eating
  • Gas, belching, and a feeling of fullness 
  • Diarrhea and/or Constipation
  • Brain fog
  • Fatigue
  • Food sensitivities and reactions (if intestinal permeability occurs) 
  • Poor nutrient absorption (B12, iron) 

There are many ways to diagnose SIBO but the diagnosis often starts with clinical suspicion and history of risk factors. Physical examination and laboratory tests can be used, although findings are nonspecific. Currently, there is no adequately validated diagnostic test for SIBO despite decades of its recognition as a clinical entity. 

The Mayo Clinic reports that In order to diagnose small intestinal bacterial overgrowth (SIBO), you may have tests to check for bacterial overgrowth in your small intestine, poor fat absorption, or other problems that may be causing or contributing to your symptoms. Common tests include:

  • Breath testing. This type of noninvasive test measures the amount of hydrogen or methane that you breathe out after drinking a mixture of glucose and water. A rapid rise in exhaled hydrogen or methane may indicate bacterial overgrowth in your small intestine. Although widely available, breath testing is less specific than other types of tests for diagnosing bacterial overgrowth. Noninvasive breath tests have been shown to have a sensitivity of 60–90% and specificity of 85%, although validation with culture is limited.
  • Small intestine aspirate and fluid culture. This is currently the gold standard test for bacterial overgrowth. To obtain the fluid sample, doctors pass a long, flexible tube (endoscope) down your throat and through your upper digestive tract to your small intestine. A sample of intestinal fluid is withdrawn and then tested in a laboratory for the growth of bacteria.

In addition to these tests, the doctor may recommend blood testing to look for vitamin deficiency or a stool evaluation to test for fat malabsorption. In some cases, the doctor may also recommend imaging tests, such as X-rays, computerized tomography (CT) scanning or magnetic resonance imaging (MRI) to look for structural abnormalities of the intestine.

As per the Mayo Clinic, whenever possible doctors treat SIBO by dealing with the underlying problem (for example, by surgically repairing a postoperative loop, stricture or fistula). However, a loop can’t always be reversed. In that case, treatment focuses on correcting nutritional deficiencies and eliminating bacterial overgrowth.

For most people, the initial way to treat bacterial overgrowth is with antibiotics. Doctors may start this treatment if symptoms and medical history strongly suggest this is the cause, even when test results are inconclusive or without any testing at all. Testing may be performed if antibiotic treatment is not effective. A short course of antibiotics often significantly reduces the number of abnormal bacteria. Unfortunately bacteria can return when the antibiotic is discontinued, so treatment may need to be long term. Some people with a loop in their small intestine may go for long periods without needing antibiotics, while others may need them regularly. Doctors may also switch among different antibiotics to help prevent bacterial resistance. Keep in mind that antibiotics wipe out most intestinal bacteria, both normal and abnormal. As a result, antibiotics can cause some of the very problems they’re trying to cure, including diarrhea. Switching among different drugs can help avoid this problem.

Correcting nutritional deficiencies is a crucial part of treating SIBO, particularly in people with severe weight loss. Malnutrition can be treated, but the damage it causes can’t always be reversed.

Some treatments may improve vitamin deficiencies, reduce intestinal distress and help with weight gain:

  • Nutritional supplements. People with SIBO may need intramuscular injections of vitamin B-12, as well as oral vitamins, calcium and iron supplements.
  • Lactose-free diet. Damage to the small intestine may cause you to lose the ability to digest milk sugar (lactose). In that case, it’s important to avoid most lactose-containing products, or use lactase preparations that help digest milk sugar.

Some affected people may tolerate yogurt because the bacteria used in the culturing process naturally break down lactose.

Physical therapy should be considered as a part of a patient’s treatment team when treating SIBO, gut health and pain issues. The gut is part of a pressure system that is regulated by the pelvic floor and diaphragm. Physical therapy can ensure both of these have good mobilty and function. Physical therapy can also help alleviate related issues, such as pelvic pain, low back pain, constipation and urinary symptoms. It can also reduce trigger points or adhesions on the abdomen that can cause pain and cramping, as scar tissues can inhibit the mobility of the abdomen and/or intestines.

References

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  2. Bacterial overgrowth of the gastrointestinal tract.Toskes PP Adv Intern Med. 1993; 38():387-407.
  3. Small intestinal bacterial overgrowth in patients with irritable bowel syndrome. Posserud I, Stotzer PO, Björnsson ES, Abrahamsson H, Simrén M Gut. 2007 Jun; 56(6):802-8. 
  4. Savage D. (1977) Microbial ecology of the gastrointestinal tract. Annu Rev Microbiol 31: 107–133
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  11.  Pimentel M., Chow E., Lin H. (2000) Eradication of small intestinal bacterial overgrowth reduces symptoms of irritable bowel syndrome. Am J Gastroenterol 95: 3503–3506
  12. Small-intestinal bacterial overgrowth in cirrhosis is related to the severity of liver disease. Pande C, Kumar A, Sarin SK Aliment Pharmacol Ther. 2009 Jun 15; 29(12):1273-81
  13. Prevalence of small intestine bacterial overgrowth diagnosed by quantitative culture of intestinal aspirate in celiac disease. Rubio-Tapia A, Barton SH, Rosenblatt JE, Murray JA J Clin Gastroenterol. 2009 Feb; 43(2):157-61.
  14. High prevalence of small intestinal bacterial overgrowth in patients with morbid obesity: a contributor to severe hepatic steatosis. Sabaté JM, Jouët P, Harnois F, Mechler C, Msika S, Grossin M, Coffin B Obes Surg. 2008 Apr; 18(4):371-7.
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  16. https://www.mayoclinic.org/diseases-conditions/small-intestinal-bacterial-overgrowth/diagnosis-treatment/drc-20370172

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Editor’s note: this post was originally published on September 2, 2020 and updated on July 31, 2024.

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