Each month, a circular structure, called follicle, grows in one of the ovaries. This structure contains the egg and grows from 5-10 mm at the beginning of the cycle to 20 mm approximately at the middle of the cycle.. When the follicle reaches this size usually on day 14 of the cycle, it ruptures (ovulation). This process requires the presence of different hormones produced at the pituitary, adrenals, ovaries, thyroid gland, etc. Any change in the production of one of these glands can interfere with this process.

The best way to determine that a patient is ovulating or not is with an echographic follicular growth pattern. In this a transvaginal ultrasound is made at specific days of the cycle in order to see the follicle growth and rupture. Through this procedure we are also able to program artificial insemination, coitus, hormone quantification, medication response, etc.

Echographic follicular growth pattern.
A. Initial phase of the cycle
B. day 10th
C. Day 12th
D. Post ovulation follicle (corpus luteum)

One of the most frequent problem with ovulation is the policystic ovary syndrome (PCO), which includes a set of symptoms, all with a common factor: anovulation (absence of ovulation). This syndrome is characterized by oligomenorrhea (infrequent menses), hirsutism (abnormal hair growth), acne, overweight, acanthosis nigricans (abnormal pigmentation in some parts of the body), and presence of cysts in one or both ovaries. There is a relationship between this syndrome and some abnormalities with insulin metabolism, and these patients have some tendency toward diabetes mellitus.

Some other causes that can affect ovulation are hormonal disturbances such as hyperthyroidism, hyperprolactinemia, chronic stress, strenuous physical efforts, eating disorders (anorexia nervosa, bulimia, etc). Treatment depends on the cause of the problem.