Chapter Contents
The physiology of the fetal hypothalamopituitary axis 989
Neonatal breast development 989
Vulval problems 990
Abnormalities of the hymen 990
Vaginal bleeding problems 991
Uterine prolapse 991
Urethral prolapse 991
Paraurethral cysts 991
Ovarian cysts 991
Gynaecological problems in neonatal life are unusual and rare. Many conditions that are thought to be pathological are commonly physiological or anatomical variants, but these variants cause considerable anxiety amongst parents. Knowledge of the physiology and anatomy of the development of the genital tract during fetal life is therefore important, so that an explanation of these variations can be offered to parents in a reassuring manner.
The physiology of the fetal hypothalamopituitary axis
The early fetal brain undergoes rapid development, and, by 5 weeks of gestation, gonadotrophin-releasing hormone (GnRH) can be detected in whole-brain extract ( ). GnRH can be localised to the hypothalamus by 8–13 weeks’ gestation ( ; ), and the hypothalamic GnRH content of female fetuses reaches a maximum at between 22 and 25 weeks’ gestation and thereafter declines ( ). This is almost certainly in response to negative feedback of circulating oestradiol.
Luteinising hormone (LH) and follicle-stimulating hormone (FSH) can be identified within the pituitary gland by 9–11 weeks’ gestation ( ; ) and the portal circulation linking the hypothalamus with the pituitary is known to be intact by 12 weeks’ gestation ( ). In response to GnRH release, FSH and LH reach their maximum between 16 and 24 weeks ( ). Subsequently, FSH levels decline, almost certainly owing to active secretion of inhibin from the granulosa cells in the ovary. During the latter part of fetal life, gonadotrophin levels are reduced and remain at low levels until birth ( ). Both inhibin and circulating oestradiol exhibit this negative-feedback mechanism.
Following birth, the contribution of placental oestradiol to the fetal circulation is withdrawn, the fetal hypothalamopituitary axis becomes activated and both GnRH and gonadotrophin levels rise immediately ( ). FSH levels and LH levels remain elevated for several months after birth, but subsequent central suppression of GnRH leads to decline in gonadotrophin levels by around 6 months of age. The central suppression of the pulse generator in the arcuate nucleus of the hypothalamus may be brought about by several modulators, including noradrenaline (norepinephrine), dopamine, central opiates, neuropeptide Y, glutamate or aspartate ( ; ; ; ). The cell receptors on the GnRH-secreting neurons are controlled by a gene encoding for transforming growth factor-alpha ( ), and this gene may well itself be controlled by the secretion of leptin ( ), a hormone produced by adipose tissue; decreasing the body mass index towards later infancy and increasing body mass at puberty may be intimately involved in the activation of the gene.
Thus, throughout fetal and early neonatal life, the hypothalamopituitary ovarian uterine axis is fully developed and active, and capable of responding to all of the appropriate integrated mechanisms. It is only the genetic downregulation of central receptors that suppresses activity after birth.
Neonatal breast development
Breast development occurs during fetal life and is well described as proceeding in female infants for several months after birth ( Fig. 38.1 ). It is occasionally associated with secretions similar to lactation. Two studies suggest that, after birth, circulating levels of oestriol, which would be maternally derived, decline rapidly, and yet breast development continues for several months after birth ( ; ). Elevated levels of oestradiol and prolactin in the neonate are directly related to breast size, the relationship being particularly strong with prolactin. Therefore it would seem that the infant’s own gonadal secretions are responsible for the control of the breast. Histological studies further support this theory ( ). Breast development in early neonatal life thus is a normal physiological process and ceases at 3–6 months of age; the breast bud may thereafter regress.
A recent study ( ) suggests that breast regression is delayed in infants who are fed soy-based infant formulas. It is suggested that phyto-oestrogens in soy-based milk preserve breast tissue in the neonate until cessation of this type of formula feed and thereafter breast tissue regresses.
Supernumerary nipples are a common finding; they extend along the nipple line on either side of the chest wall, down the abdomen and may occur in the labia. Bilateral ectopic breast tissue has been described in the vulva ( ).
Vulval problems
Labial cysts in the newborn are rare, and occur in about 6 per 1000 female infants. These congenital cysts require no treatment whatsoever, and conservative management leads to complete resolution within 2–3 months of life. No surgical approach should be taken in these circumstances ( ).
Inguinal hernia in infants is very common and is encountered in approximately 1–3% of full-term newborns and 3–5% of premature babies ( ). Surgical management of this involves closure of the hernia ( Ch. 29, part 4 ). It is important to be aware that, in female infants, a differential diagnosis of an irreducible inguinal mass must include the presence of either a prolapsed ovary or the uterus and ovary, and, in female infants with ambiguous genitalia, the inguinal mass may be a testis. It is unusual for these to be seen immediately after birth, but they may become obvious in the ensuing months. Ultrasound of these masses can be extremely useful and may help to differentiate the presence of ovarian tissue in the hernia sac and also aid in differentiating the presence of an ovary or a testis. It is important that, when these masses are detected, early treatment is offered, as correction of this anatomical defect will reduce the risk of torsion and infarction and subsequent loss of the gonad. This is particularly important when the herniation is an ovary, which requires conservation.
Abnormalities of the hymen
The hymen at birth is usually annular or fimbriated and commonly associated with external ridges. Hymenal tags are extremely common at birth ( ), and are often misdiagnosed as ‘prolapse’. The hymen changes its characteristics during the first 3 years of life and becomes crescentic by age 3 years in the vast majority, with the external ridges disappearing ( ). Problems in neonatal life that are associated with peripheral oedema often lead to oedema of the hymen, which may protrude beyond the vulval entrance and again be mistaken for a prolapse.
Failure of the hymen to perforate during embryological life may lead to retention of vaginal secretions which cannot escape and the vagina distends proximal to the hymen. Although these membranes are often referred to as imperforate hymen, it is likely that this is not strictly correct and that these membranes are transverse vaginal septa, resulting from failure of fusion of the urogenital sinus and the downgrowth of the vaginal plate from the müllerian structures. When a large quantity of fluid collects, there may be difficulty in emptying the bladder, as the distended vagina fills the pelvis, and the child may be very fretful and clearly in discomfort. The physical signs are of a lower abdominal cystic swelling and a bulging membrane at the introitus ( Fig. 38.2 ). Diagnosis is extremely important, as misdiagnoses abound in which laparotomy has been performed, and even hysterectomy, and this is absolutely unnecessary. The most common misdiagnoses are to believe that this is either a swelling which is an ovarian cyst or, occasionally, a full bladder with urethral prolapse. Ultrasound imaging may diagnose a hydrocolpos both antenatally and after delivery, and the condition has been described as early as 25 weeks’ gestation ( ). With ultrasound, it is simple to demonstrate the uterus sitting above a distended vagina, when the diagnosis of hydrocolpos can be made. Treatment is straightforward in most cases: the intact membrane is incised and the retained fluid released. Redundant portions of the membrane may be excised and the procedure completed. If the obstruction is more extensive owing to a wide transverse septum, great care is needed to avoid damage to the bladder and rectum, but an end-to-end anastomosis can be achieved to result in a normal vagina. These cases of hydrocolpos are probably exceptional, as most cases of transverse vaginal septum are not diagnosed until puberty ( ).
