It is now understood as a chronic inflammatory condition, meaning the immune system and inflammatory pathways play a key role in how symptoms develop and persist. This can lead to scar tissue formation and worsen irritation within the pelvis and abdomen.

In some cases, endometriosis can also involve or irritate nerves within the pelvis, which can contribute to more complex pain patterns, including sharp, radiating, or nerve-type pain within the pelvis, lower back, vagina, buttock, and upper thighs.
Importantly, endometriosis frequently overlaps with other chronic pain conditions affecting the bowel, bladder, and vagina. Many patients experience symptoms consistent with irritable bowel syndrome (IBS)—such as bloating, constipation, or diarrhea—and interstitial cystitis (painful bladder syndrome), which can cause urinary urgency, frequency, and bladder discomfort. Vaginal and pelvic floor conditions, including vaginismus, vestibulodynia, and vulvodynia, are commonly associated and contribute to pain, burning and heightened sensitivity with penetrative intercourse. These overlapping conditions are often linked through shared nerve pathways, pelvic floor dysfunction, and inflammation.

