A 16-year-old G0P0 patient presents with lower pelvic pain related to her cycle, occurring midcycle with unremarkable pelvic examination. What is the most likely diagnosis?

The most likely diagnosis in this scenario is Mittelschmerz, which is a term used to describe the mid-cycle pain that some women experience during ovulation. This phenomenon commonly occurs in the middle of the menstrual cycle, typically around day 14, coinciding with the release of an egg from the ovaries.

In this case, the patient's age, G0P0 status, and the description of her symptoms as lower pelvic pain related to her cycle occurring midcycle align well with typical features of Mittelschmerz. The pelvic examination being unremarkable further supports this diagnosis, as there would not be any significant findings such as tenderness or masses that might suggest other conditions.

Endometriosis might present with cyclical pain but is usually associated with a more complex clinical picture, including painful periods and other symptoms, as well as potentially abnormal findings on pelvic examination. Functional ovarian cysts can also cause pain but are often accompanied by other symptoms or findings, such as an adnexal mass, which would likely be visible upon examination. Pelvic inflammatory disease typically presents with more severe symptoms, including fever and significant tenderness on examination, which again would not be consistent with an unremarkable exam.

Thus, the presentation strongly indicates that Mittelschmerz is