Chapter 051. Menstrual Disorders and Pelvic Pain (Part 2)

Role of the hypothalamic-pituitary-gonadal axis in the etiology of amenorrhea. Gonadotropin-releasing hormone (GnRH) secretion from the hypothalamus stimulates follicle-stimulating hormone (FSH) and luteinizing hormone (LH) secretion from the pituitary to induce ovarian folliculogenesis and steroidogenesis. Ovarian secretion of estradiol and progesterone controls the shedding of the endometrium, resulting in menses and, in combination with the inhibins, provides feedback regulation of the hypothalamus and pituitary to control secretion of FSH and LH. The prevalence of amenorrhea resulting from abnormalities at each level of the reproductive system (hypothalamus, pituitary, ovary, uterus, and outflow tract) varies depending on whether amenorrhea is primary...
Nội dung trích xuất từ tài liệu:
Chapter 051. Menstrual Disorders and Pelvic Pain (Part 2) Chapter 051. Menstrual Disorders and Pelvic Pain (Part 2)Figure 51-1 Role of the hypothalamic-pituitary-gonadal axis in the etiology ofamenorrhea. Gonadotropin-releasing hormone (GnRH) secretion from the hypothalamusstimulates follicle-stimulating hormone (FSH) and luteinizing hormone (LH)secretion from the pituitary to induce ovarian folliculogenesis and steroidogenesis.Ovarian secretion of estradiol and progesterone controls the shedding of theendometrium, resulting in menses and, in combination with the inhibins, providesfeedback regulation of the hypothalamus and pituitary to control secretion of FSHand LH. The prevalence of amenorrhea resulting from abnormalities at each levelof the reproductive system (hypothalamus, pituitary, ovary, uterus, and outflowtract) varies depending on whether amenorrhea is primary or secondary. PCOS,polycystic ovarian syndrome. Disorders of menstrual function can be thought of in two main categories:disorders of the uterus and outflow tract and disorders of ovulation. Many of theconditions that cause primary amenorrhea are congenital but go unrecognized untilthe time of normal puberty (e.g., genetic, chromosomal, and anatomicabnormalities). All causes of secondary amenorrhea can also cause primaryamenorrhea. Disorders of the Uterus or Outflow Tract Abnormalities of the uterus and outflow tract typically present as primaryamenorrhea. In patients with normal pubertal development and a blind vagina, thedifferential diagnosis includes obstruction by a transverse vaginal septum orimperforate hymen; müllerian agenesis (Mayer-Rokitansky-Kuster-Hausersyndrome), which has been associated with mutations in the WNT4 gene; andandrogen insensitivity syndrome (AIS), which is an X-linked recessive disorderthat accounts for ~10% of all cases of primary amenorrhea (Chap. 340). Patientswith AIS have a 46, XY karyotype, but because of the lack of androgen receptorresponsiveness, they have severe underandrogenization and female externalgenitalia. The absence of pubic and axillary hair distinguishes them clinically frompatients with müllerian agenesis. Asherman syndrome presents as secondaryamenorrhea or hypomenorrhea and results from partial or complete obliteration ofthe uterine cavity by adhesions that prevent normal growth and shedding of theendometrium. Curettage performed for pregnancy complications accounts for>90% of cases; genital tuberculosis is an important cause in endemic regions. Disorders of Uterus or Outflow Tract: Treatment Obstruction of the outflow tract requires surgical correction. The risk ofendometriosis is increased with this condition, perhaps because of retrogrademenstrual flow. Müllerian agenesis may also require surgical intervention,although vaginal dilatation is adequate in some patients. Because ovarian functionis normal, assisted reproductive techniques can be used with a surrogate carrier.Androgen resistance syndrome requires gonadectomy because there is risk ofgonadoblastoma in the dysgenetic gonads. Whether this should be performed inearly childhood or after completion of breast development is controversial.Estrogen replacement is indicated after gonadectomy, and vaginal dilatation maybe required to allow sexual intercourse. Disorders of Ovulation Once uterus and outflow tract abnormalities have been excluded, all othercauses of amenorrhea involve disorders of ovulation. The differential diagnosis isbased on the results of initial tests including a pregnancy test, gonadotropins, andassessment of hyperandrogenism (Fig. 51-2). Figure 51-2