Final answer:
A 27-year-old patient experiencing a menstrual cycle every 16 or 17 days is experiencing Polymenorrhea, frequent menstrual cycles less than 21 days apart. The correct answer is option C.
Step-by-step explanation:
The menstrual issue described by the 27-year-old patient, who is experiencing a period every 16 or 17 days over the past 2½ months, can be termed Polymenorrhea. Polymenorrhea refers to the occurrence of menstrual cycles more frequently than is considered normal, typically defined as cycles less than 21 days apart.
This contrasts with Hypomenorrhea, which refers to reduced menstrual flow; Metrorrhagia, which indicates bleeding at irregular intervals, particularly between the expected menstrual periods; and Menorrhagia, which is characterized by abnormally heavy or prolonged menstrual bleeding.
The patient should seek further medical evaluation to determine the underlying cause of her Polymenorrhea, which may include hormonal imbalances, stress, excessive weight loss, or other medical conditions.