Endometriosis is defined as the presence of endometrial tissue outside the uterus. Which site is most commonly affected?

Endometriosis is defined as the presence of endometrial tissue outside the uterus. Which site is most commonly affected?

• A. Ovaries
• B. Uterine myometrium
• C. Fallopian tubes
• D. Liver

Answer: (A)

Endometriosis involves endometrial tissue located outside the uterus, most commonly spreading within the pelvis. The ovaries are the single most frequent site, where ectopic endometrium can form ovarian endometriomas (often called chocolate cysts) due to cyclic hemorrhage and ongoing inflammation. This tendency to involve the ovaries fits with the typical pelvic distribution seen in endometriosis and explains why ovarian implants are such a classic finding. In contrast, tissue within the uterine wall is characteristic of adenomyosis, not endometriosis, and the liver is a much less common, distant site. Thus, the ovaries best fit as the most commonly affected location.

Endometriosis involves endometrial tissue located outside the uterus, most commonly spreading within the pelvis. The ovaries are the single most frequent site, where ectopic endometrium can form ovarian endometriomas (often called chocolate cysts) due to cyclic hemorrhage and ongoing inflammation. This tendency to involve the ovaries fits with the typical pelvic distribution seen in endometriosis and explains why ovarian implants are such a classic finding. In contrast, tissue within the uterine wall is characteristic of adenomyosis, not endometriosis, and the liver is a much less common, distant site. Thus, the ovaries best fit as the most commonly affected location.