What is characterized by irregular menstruation?

Metrorrhagia refers to irregular menstruation, which encompasses any abnormal bleeding that occurs outside of a normal menstrual cycle. This can manifest as bleeding in between periods or variations in the regularity and timing of menstrual cycles. It often indicates an underlying issue, such as hormonal imbalances, structural abnormalities in the uterus, or other gynecological conditions.

Menorrhagia, on the other hand, specifically denotes heavy or prolonged menstrual bleeding during the regular menstrual periods, rather than irregularity in the timing or occurrence of menstruation.

Prolapse involves the displacement of an organ, such as the uterus, and does not directly relate to the timing or irregularity of menstruation. Orchitis is the inflammation of the testes, which is not connected to menstrual cycles.

Thus, the correct characterization of irregular menstruation is most accurately defined by metrorrhagia.