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Pediatric gynecology is a unique subspecialty that encompasses knowledge from various specialties including general pediatrics, gynecology, and 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. In 1986, the North American Society for Pediatric and Adolescent Gynecology (NASPAG) was established to conduct and encourage medical education and research in the field of pediatric and adolescent gynecology (PAG). To further this mission, PAG fellowships are now available nationwide.
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Gynecologic disorders in children can differ greatly from those encountered in the adult female. Even the simple physical examination of the genitalia differs significantly. A thorough understanding of these differences can aid in diagnosis.
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PHYSIOLOGY AND ANATOMY
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Hypothalamic-Pituitary-Ovarian Axis
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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. 17-5, p. 378). They form axons that extend to the median eminence and to the capillary plexus of the pituitary portal system (Fig. 16-9, p. 344). GnRH, 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 from the anterior pituitary. The gonadotropins are follicle-stimulating hormone (FSH) and luteinizing hormone (LH). In turn, the pulsatile release of gonadotropins stimulates ovarian synthesis and release of sex 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, sex steroids exert a negative feedback on secretion of both hypothalamic GnRH and pituitary gonadotropins. During this time, oocyte numbers decline through a process of gene-related apoptosis to reach a level of 1 to 2 million by birth (Vaskivuo, 2001).
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At birth, FSH and LH concentrations rise abruptly in response to the fall in placental estrogen levels. Levels of these gonadotropins are highest in the first 3 months of life (Fig. 15-1). This transient rise in their levels is followed by an increase in sex steroid concentrations. This rise is thought to explain instances of neonatal breast budding, minor bleeding from endometrial shedding, short-lived ovarian cysts, and transient white vaginal mucous discharge. Following these initial months, gonadotropin levels gradually decline to reach prepubertal levels by age 1 to 2 years.
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