A 15-year-old girl is brought to the office due to irregular menstrual periods. Menarche was at age 13, and since then her periods have been irregular with cycles varying from 3 to 8 weeks. The patient has no chronic medical issues, has never had surgery, and takes no medications. Her mother and older sister have polycystic ovary syndrome, and both take oral contraceptives. The patient has never been sexually active. Vital signs are normal. Physical examination shows normal hair distribution with Tanner V secondary sexual characteristics. Abdominal examination is normal. There is dark red blood noted at the cervical os with no active bleeding. Serum prolactin and TSH levels are normal. Administration of micronized oral progesterone results in withdrawal bleeding in 3 days. Pelvic ultrasound reveals normal ovaries and uterus. Which of the following is the most likely explanation of this patient's irregular menstrual periods?

Question

A 15-year-old girl is brought to the office due to irregular menstrual periods.  Menarche was at age 13, and since then her periods have been irregular with cycles varying from 3 to 8 weeks.  The patient has no chronic medical issues, has never had surgery, and takes no medications.  Her mother and older sister have polycystic ovary syndrome, and both take oral contraceptives.  The patient has never been sexually active.  Vital signs are normal.  Physical examination shows normal hair distribution with Tanner V secondary sexual characteristics.  Abdominal examination is normal.  There is dark red blood noted at the cervical os with no active bleeding.  Serum prolactin and TSH levels are normal.  Administration of micronized oral progesterone results in withdrawal bleeding in 3 days.  Pelvic ultrasound reveals normal ovaries and uterus.  Which of the following is the most likely explanation of this patient's irregular menstrual periods?

Quizplus · Accepted Answer

11ec25c8_d9a6_8aae_bc81_83becb2538af_MD0003_00 The initial menstrual cycles in adolescents are irregular and anovulatory. The abnormal uterine bleeding (AUB) that follows menarche is due to immaturity of the developing hypothalamic-pituitary-gonadal axis that produces inadequate quantities and proportions of gonadotropin-releasing hormone, and subsequently FSH and LH, required to induce ovulation. In the absence of ovulation, menstrual cycles lack their regular periodicity. The endometrium builds up under the influence of estrogen, but without the influence of progesterone, the cue to slough the endometrium is lacking and menstrual-like bleeding occurs due to estrogen breakthrough bleeding. Normally, progesterone is produced in increased amounts by the corpus luteum following ovulation, and withdrawal of this progesterone as the corpus luteum degenerates results in menses. absence of ovulation In patients with AUB, bleeding after exogenous progesterone administration confirms normal endogenous estrogen production and proliferative endometrium. It also eliminates causes of estrogen deficiency (eg, primary ovarian insufficiency), endometrial abnormalities (eg, intrauterine adhesions), and outlet tract abnormalities (eg, imperforate hymen). Treatment of AUB in adolescents with either progestin-only or combination estrogen/progestin oral contraceptives is indicated when bleeding is disruptive to activities, is heavy, or results in anemia. Anovulation typically resolves 1-4 years postmenarche, after which menstrual cycles normalize. (Choices A and C) Excess LH secretion and androgen excess are characteristic of polycystic ovary syndrome. Clinical features include irregular menses, signs of hirsutism, and multiple small "pearl-string" ovarian cysts on ultrasound. This patient has no signs of hirsutism and shows normal ovaries on ultrasound, making this diagnosis less likely. (Choice B) Estrogen deficiency, characteristic of primary ovarian insufficiency, typically presents with secondary amenorrhea. Patients with estrogen deficiency do not have bleeding after progesterone stimulation due to the lack of proliferative endometrium. (Choice E) Intrauterine adhesions (eg, Asherman syndrome) are a cause of secondary amenorrhea typically due to previous uterine instrumentation (eg, dilation and curettage) or infection (eg, endometritis). In these patients, a progesterone withdrawal bleed does not occur due to the lack of endometrial tissue. Educational objective: The initial menstrual cycles in adolescents are irregular and anovulatory due to hypothalamic-pituitary-gonadal axis immaturity and insufficient secretion of gonadotropin-releasing hormone. References: Dysfunctional uterine bleeding in adolescent girls and evaluation of their response to treatment. (http://www.ncbi.nlm.nih.gov/pubmed/24192679)

A 15-Year-Old Girl Is Brought to the Office Due to Irregular