Differential diagnosis of bowel diseases: focus on irritable bowel syndrome and intestinal endometriosis

Irritable bowel syndrome (IBS) is a chronic functional bowel disorder characterized by abdominal pain associated with defecation and changes in stool frequency and pattern. Diagnosing IBS is one of the most complex and challenging in gastroenterology. Differential diagnosis should include a wide range of conditions, not only organic pathologies of the gastrointestinal tract but also pathologies of other organs and systems, including gynecological diseases. Endometriosis is a pathological process that involves the presence of tissue similar to the endometrium outside the uterine cavity, based on its morphological and functional properties. Endometriosis affects 10% (190 million) of women of reproductive age worldwide. Intestinal endometriosis is a pathological condition characterized by infiltration of the intestine with ectopic endometrial tissue. When examining the relationship between IBS and endometriosis/intestinal endometriosis, we used sources from PubMed and eLibrary published before February 25, 2026. This review demonstrates that the pathogenesis of IBS and endometriosis share several common factors, including genetic factors, intestinal microbiota dysbiosis, immune disorders, and low-grade chronic inflammation. In IBS, intestinal symptoms may coexist with gynecological symptoms, while gynecological symptoms in intestinal endometriosis and genital endometriosis may coexist with gastrointestinal symptoms, which can create certain diagnostic challenges. When differentially diagnosing IBS and intestinal diseases, the possible presence of genital endometriosis and intestinal endometriosis must also be considered. The presence of gynecological symptoms in patients with intestinal symptoms requires an interdisciplinary approach to differential diagnosis and close interaction between internists and gynecologists. Keywords: intestinal diseases, irritable bowel syndrome, genital endometriosis, intestinal endometriosis, clinical presentation, pathogenesis, differential diagnosis.