FIGURE 51.1 Strategy for initial diagnostic evaluation of the patient with oligomenorrhea T, testosterone; TSH, thyroid-stimulating hormone; FSH, follicle-stimulating hormone; PCOS, polycystic ovary syndrome A common cause for oligomenorrhea or amenorrhea is current or recent use of a hormonal contraceptive method A parent may bring their child to a healthcare provider for complaint of oligomenorrhea; a confidential history may reveal that the patient is on a hormonal contraceptive method About half of women using contraceptive medroxyprogesterone injections for 12 months have amenorrhea; after years of use, the proportion with amenorrhea is 68% Amenorrhea also occurs in about 2% of menstrual cycles among patients taking combined hormonal contraceptives (pills, rings, patch) Some birth control pills are packaged for extended use, and the patient may only have withdrawal bleeding four times a year However, amenorrhea persisting 12 months after the last injection of medroxyprogesterone or months after birth control pills, ring, or patch have been stopped should be evaluated in the standard fashion ENDOCRINE ABNORMALITIES Hyperandrogenism Polycystic Ovarian Syndrome Classically, hirsutism, obesity, ovarian enlargement, amenorrhea, or infertility constitutes the clinical features of polycystic ovary syndrome (PCOS, previously