Is it IBS or Endometriosis?

March is Endometriosis Awareness Month.

This gives us the perfect opportunity to talk about IBS (Irritable Bowel Syndrome). IBS can either co-exist with endometriosis or worse, mask it, further delaying its diagnosis. At present, endometriosis is diagnosed anywhere from 7 to 12 years after the onset of its symptoms.

But what is endometriosis? Endometriosis is characterized by the presence of tissue that is similar to, but not the same as, endometrial tissue. However, unlike endometrial tissue which is present inside the uterus, this tissue is disseminated outside the uterine cavity. Endometriosis is frequently present with painful and heavy menstruation and is therefore often misrepresented as a reproductive disease. However, many studies have found its presence outside of the pelvis, in the colon, lungs, diaphragm, eyes, and even in the brain - in other words, quite far away from the reproductive system.

Endometriosis, when present in the colon (the most common site outside of the pelvis), can give rise to symptoms very similar to IBS. 

Symptoms like abdominal pain, bloating, distention, diarrhea & constipation sound like something must be wrong with the gut, so it is quite common to summarily implicate the GI system and arrive at a diagnosis of IBS. However, inflammation caused by endo lesions can cause similar gut symptoms in the absence of IBS.

Let’s see how IBS is usually diagnosed, particularly since it doesn’t have a gold standard test, and colonoscopy is inadequate to correctly diagnose it.

IBS is diagnosed based on:⁣

• Your symptoms⁣ 
• Detailed history⁣
• Ruling out red flags such as unexplained anemia, blood in stool, family history of colorectal cancer, or IBD⁣ (irritable bowel disease)
• Physical exam - should be normal⁣
• Most importantly— the Rome IV criteria⁣

According to the 𝗥𝗼𝗺𝗲 𝗜𝗩 𝗰𝗿𝗶𝘁𝗲𝗿𝗶𝗮:⁣

IBS is a functional bowel disorder, in which recurrent abdominal pain is associated with defecation or change in bowel habits.⁣

• Disordered bowel habit should be present - constipation, diarrhea, or a mix⁣
• Symptoms onset should occur at least 6 months prior to the diagnosis & symptoms should be present for the last 3 months.⁣
• Abdominal pain should last for at least 1 day per week  in the last 3 months ⁣

 Plus, should be associated with 2 or more of⁣: 

• Related to defecation⁣
• Change in frequency of bowel movement⁣
• Change in the form of stool⁣

Endometriosis, on the other hand, can only be effectively diagnosed with laparoscopic surgery, which unfortunately is not readily accessible for a majority of the world population. Advances are being made in the use of ultrasound and MRI (Magnetic Resonance Imaging) for the diagnosis of endometriosis, but these tools are still unable to detect all types of lesions, and the success rate is heavily dependent on the skill of the radiologist studying the imaging. 

Colonoscopy is not a great diagnostic tool for Endo either, as it only picks up the bigger lesions invading the lining of the colon.

Rome IV criteria are essential to properly rule out IBS. However, a thorough history & review of other systems are also important as fluctuation in symptoms can really complicate things & confuse the clinician.⁣

⁣Similarly, to rule out Endo, a detailed history & seeing an Endo specialist are super important, especially if regular IBS treatment is not addressing your IBS symptoms, and you notice fluctuations in your symptoms in relation to your menstrual cycle.

References:

Endometriosis and irritable bowel syndrome: A systematic review and meta-analyses. PMID: 35957857

Intestinal endometriosis: the great masquerader. PMID: 15341718