What is the most common pelvic mass found in reproductive-age women?

The most common pelvic mass found in reproductive-age women is ovarian cysts. Ovarian cysts are fluid-filled sacs that develop on the ovaries and are particularly prevalent during a woman's reproductive years due to the normal hormonal cycles and the monthly ovulation process. Many women will experience these cysts at some point, and they are usually benign and asymptomatic, often resolving on their own without treatment.

In contrast, while other options like uterine fibroids, ovarian masses, and endometriomas do occur in this population, they are not as universally common as ovarian cysts. Uterine fibroids can be prevalent but tend to affect women in their 30s and 40s rather than being a general characteristic of reproductive-age women. Ovarian masses may be present, but they encompass a broader category that includes both benign and malignant conditions, making them less common overall. Endometriomas, associated with endometriosis, are also less prevalent than simple ovarian cysts. Therefore, the prominence and frequency of ovarian cysts in reproductive-age women make them the most common pelvic mass encountered in this demographic.