Pediatric gynecology is a unique subspecialty that encompasses knowledge from various specialties including general pediatrics, gynecology, reproductive endocrinology, as well as pediatric endocrinology and pediatric urology. Treatment of a particular patient may thus require the collaboration of clinicians from one or more of these fields.
Gynecologic disorders in children can differ greatly from those encountered in the adult female. Even the simple physical examination of the genitalia differs significantly. Thus, a thorough understanding of such differences can aid in clarifying and diagnosing the variety of gynecologic abnormalities seen in this age group.
Hypothalamic-Pituitary-Ovarian (HPO) Axis
A carefully orchestrated cascade of events unfolds in the neuroendocrine system and regulates development of the female reproductive system.
In utero, gonadotropin-releasing hormone (GnRH) neurons develop in the olfactory placode. These neurons migrate through the forebrain to the arcuate nucleus of the hypothalamus by 11 weeks' gestation (Fig. 16-5). They form axons that extend to the median eminence and to the capillary plexus of the pituitary portal system (Fig. 15-11) (Ronnekliev, 1990; Schwanzel-Fukuda, 1989; Silverman, 1987). Gonadotropin-releasing hormone, a decapeptide, is influenced by higher cortical centers and is released from these neurons in a pulsatile fashion into the pituitary portal plexus. As a result, by midgestation, the GnRH “pulse generator” stimulates secretion of gonadotropins, that is, follicle-stimulating hormone (FSH) and luteinizing hormone (LH), from the anterior pituitary. In turn, the pulsatile release of gonadotropins stimulates ovarian synthesis and release of gonadal steroid hormones. Concurrently, accelerated germ cell division and follicular development begins, resulting in the creation of 6 to 7 million oocytes by 5 months' gestation. By late gestation, gonadal steroids exert a negative feedback upon secretion of both the pituitary gonadotropins and hypothalamic GnRH. During this time, oocyte number decreases through a process of gene-related apoptosis to reach a level of 1 to 2 million by birth (Vaskivuo, 2001).
At birth, FSH and LH concentrations rise abruptly in response to the fall in placental estrogen levels and are highest in the first 3 months of life (Fig. 14-1). This transient rise in gonadotropin levels is followed by an increase in gonadal steroid concentrations, which is thought to explain instances of neonatal breast budding, minor bleeding from endometrial shedding, and short-lived ovarian cysts. Following these initial months, gonadotropin levels gradually decline to reach prepubertal levels by age 1 to 4 years.
Variation in oocyte number and hormone levels during prenatal and postnatal periods. (DHEA = dehydroepiandrosterone; FSH = follicle-stimulating hormone; hCG = human chorionic gonadotropin; LH = luteinizing hormone.) (Adapted from Speroff, 2005, with permission.)
The childhood years are thus characterized by low plasma levels of FSH, LH, and estradiol. Estradiol levels typically measure <10 pg/mL, and LH values are <0.3 mIU/mL. Both may be assessed if precocious development is suspected (Neely, 1995; Resende, 2007; Sathasivam, 2010). ...