Which condition is characterized by the presence of endometrial tissue outside the uterus?

Endometriosis is characterized by the presence of endometrial-like tissue situated outside the uterine cavity, which commonly affects areas such as the ovaries, fallopian tubes, and the pelvic lining. This abnormal growth can lead to symptoms such as chronic pelvic pain, dysmenorrhea, and infertility.

In endometriosis, the tissue responds to hormonal changes similar to the endometrial tissue within the uterus, which can cause inflammation, scarring, and the formation of adhesions. The specific locations where this tissue grows and the response to hormonal fluctuations are key aspects of the condition, distinguishing it from other gynecological issues.

Conditions like uterine fibroids, ovarian cysts, and pelvic adhesions involve different types of tissue or pathophysiological changes. Uterine fibroids are benign tumors made of smooth muscle and connective tissue, ovarian cysts generally involve fluid-filled sacs on the ovaries rather than endometrial tissue, and pelvic adhesions are bands of scar tissue that can form after surgery or inflammation but do not involve endometrial tissue. Each of these conditions presents different pathologies and symptoms, highlighting why endometriosis is uniquely defined by the presence of endometrial tissue outside its normal location.