IBS and Endometriosis: The Painful Overlap Most Doctors Miss

IBS and Endometriosis: The Painful Overlap Most Doctors Miss

By Dr. Onikepe Adegbola, MD PhD — Johns Hopkins-trained physician-scientist and founder of Casa de Sante

How Endometriosis Causes GI Symptoms

Direct Bowel Involvement

• Endometriotic implants grow on the bowel surface in 5-12% of endometriosis patients. Most common locations: rectosigmoid colon, appendix, and small bowel.
• These implants respond to the menstrual cycle (growing with estrogen, bleeding with menstruation) → cyclic bowel wall inflammation → pain, bleeding, and altered motility that PERFECTLY mimics IBS.
• Deep infiltrating endometriosis (DIE) can penetrate through the bowel wall → strictures → obstruction symptoms (severe constipation, bloating, vomiting). This is a surgical condition, not a dietary one.

Indirect Mechanisms

• Pelvic inflammation: Even without direct bowel implants, endometriosis creates a chronic inflammatory environment in the pelvis → affects bowel motility and sensitivity through proximity and shared nerve supply.
• Adhesions: Endometriosis causes adhesions (scar tissue) between pelvic organs → can tether the bowel → mechanical restriction of normal bowel movement → constipation, pain with bowel movements.
• Central sensitization: Chronic pelvic pain → nervous system upregulation → visceral hypersensitivity that ALSO applies to the gut. This is the same mechanism as IBS visceral hypersensitivity — but triggered by endometriosis.

Distinguishing Endometriosis from IBS

Symptom Pattern Differences

• Cyclic symptoms: Endometriosis GI symptoms worsen predictably with menstruation. IBS symptoms can fluctuate with the cycle but not as dramatically or consistently.
• Pelvic pain: Endometriosis causes pelvic pain BETWEEN periods (not just during). IBS abdominal pain is typically lower abdominal but not specifically pelvic.
• Dyspareunia: Pain during intercourse (especially deep penetration) is common in endometriosis, uncommon in IBS.
• Rectal bleeding during menstruation: Highly specific for bowel endometriosis. NOT a feature of IBS.
• Infertility: 30-50% of women with endometriosis experience infertility. IBS does not cause infertility.

When to Push for Evaluation

• You've been diagnosed with IBS but your symptoms are dramatically worse during your period.
• Standard IBS treatments (low FODMAP, antispasmodics) provide minimal or no relief.
• You have painful periods that interfere with daily activities (this is NOT normal — despite cultural normalization of period pain).
• Family history of endometriosis (first-degree relative = 7x increased risk).

Treatment Approach

Medical Management

• Hormonal suppression: Continuous oral contraceptives, GnRH agonists, or dienogest suppress menstruation → suppress the cyclic inflammation → reduce GI symptoms from endometriosis.
• If hormonal therapy resolves your "IBS" symptoms: That's strong evidence that the symptoms were endometriosis-driven, not true IBS.

Surgical

• Laparoscopic excision of endometriotic implants — especially bowel implants — can resolve GI symptoms that failed all dietary and medical management.
• Post-surgical: some patients develop TRUE IBS from adhesion formation or nerve damage. Others have complete GI symptom resolution.

Managing Both Conditions

• Some patients have BOTH endometriosis AND IBS (two separate conditions coexisting). After adequate endometriosis treatment, remaining GI symptoms may represent true IBS → standard IBS management (low FODMAP, etc.) becomes appropriate.
• The low FODMAP diet can help manage GI symptoms regardless of whether they're from endometriosis or IBS — but it won't address the underlying endometriosis pathology. Diet manages symptoms; it doesn't treat the disease.