Is It Really IBS? When Bowel Endometriosis Is the Real Culprit

Many people are diagnosed with Irritable Bowel Syndrome (IBS) when they actually have endometriosis affecting their bowel or colon. Understanding the difference is crucial to getting the right treatment and relief.

IBS and Endometriosis: Why the Confusion Happens

IBS and endometriosis can cause very similar digestive symptoms, including:

Bloating
Constipation or diarrhea
Nausea
Abdominal cramping
Gas and painful bowel movements

Because these symptoms overlap, patients (especially women and AFAB individuals) are often told they have IBS—without proper testing for other causes, including endometriosis.

Key Point: If your IBS symptoms get worse around your period, don’t respond well to diet changes or medications, or are paired with painful periods or pelvic pain—endometriosis could be the real cause.

What Is Bowel Endometriosis?

Endometriosis occurs when tissue similar to the uterine lining grows outside the uterus. When it grows on the bowel or colon, it's called bowel endometriosis. It can affect:

The rectum
The sigmoid colon
The small intestine
The appendix

Bowel endometriosis may cause:

Painful bowel movements (especially during periods)
Rectal bleeding during periods
Severe bloating (“endo belly”)
Changes in stool consistency or frequency

How IBS Is Diagnosed—and Why It’s Often Inaccurate

IBS is a diagnosis of exclusion, meaning it's often diagnosed when doctors don’t find another cause. The problem? Many physicians do not investigate endometriosis thoroughly before labeling someone with IBS.

Most IBS diagnoses rely on:

Symptom questionnaires
Ruling out conditions like Crohn’s or celiac disease
No imaging or surgical confirmation

This approach can miss deep-infiltrating endometriosis, especially on the bowel, which often requires laparoscopy (a surgical procedure) for diagnosis.

Clues That It Might Be Endometriosis, Not IBS

✅ Symptoms worsen with your menstrual cycle
✅ You have painful or heavy periods
✅ You’ve had pelvic pain or been told you might have fibroids or ovarian cysts
✅ IBS treatments (like fiber, probiotics, or gut-directed medications) haven’t worked
✅ You experience deep pain with intercourse or rectal bleeding during your period

Take Action: Keep a symptom diary and track how symptoms relate to your menstrual cycle. Bring this to your doctor.

Getting the Right Diagnosis

If you suspect bowel endometriosis:

See a specialist – Ideally, a gynecologist who specializes in endometriosis, particularly excision surgery.
Get proper imaging – Transvaginal ultrasound with bowel prep or an MRI with an endometriosis protocol can help detect lesions.
Ask about laparoscopy – A skilled excision surgeon can visually confirm and treat bowel endometriosis during surgery.

Treatment Options

IBS is typically managed with diet changes and medications. But bowel endometriosis often requires excision surgery, the gold standard treatment.

Excision surgery involves cutting out endometriosis lesions (including those on the bowel) rather than burning them (ablation), which has a higher recurrence rate and may not fully remove the disease.

Important: Not all gynecologists are trained in excising bowel endometriosis. Always seek a true endometriosis specialist.

References

International Working Group of AAGL et al. (2021). Consensus on the Surgical Management of Deep Endometriosis. J Minim Invasive Gynecol. https://doi.org/10.1016/j.jmig.2020.09.004

Endometriosis Foundation of America. “Understanding Bowel Endometriosis.” https://www.endofound.org

Giudice, L. C. (2010). Clinical practice. Endometriosis. N Engl J Med, 362(25), 2389–2398. https://doi.org/10.1056/NEJMcp1000274

Vercellini, P., et al. (2006). Bowel endometriosis: current perspectives on diagnosis and treatment. Fertil Steril, 85(6), 1377–1390. https://doi.org/10.1016/j.fertnstert.2006.03.011