Which tests distinguish IBS from IBD and bowel endometriosis?

We often start by looking for objective signs of inflammation. Stool fecal calprotectin plus blood tests like C-reactive protein (CRP) and a complete blood count can help differentiate inflammatory bowel disease (IBD) from conditions that don’t typically raise inflammatory markers. When these are elevated, it supports IBD and usually leads to colonoscopy with biopsy to confirm the diagnosis and define the type and extent of inflammation.

If inflammatory markers are normal but symptoms persist, IBS becomes more likely—but bowel endometriosis can look very similar and won’t reliably raise calprotectin or CRP. In that setting, targeted pelvic imaging such as transvaginal ultrasound or pelvic MRI can help evaluate for deep endometriosis involving the bowel. When Crohn’s disease is suspected beyond the reach of standard colonoscopy, MRI enterography is often used to assess the small bowel, and our team can help coordinate the right testing based on your symptom pattern.