••• Chapter 40^ Pediatric and Adolescent Gynecology^393
❍ List five ways in which the vagina of a child is different from the vagina of an adult.
(1) Thinner epithelium.
(2) Neutral pH.
(3) Lack of glycogen.
(4) Lack of lactobacilli.
(5) Insufficient level of antibodies to help resist infection.
❍ What is the initial endocrinologic change associated with the onset of puberty?
The occurrence of episodic pulses of luteinizing hormone (LH) occurring during sleep.
❍ What is the last endocrinologic event of puberty?
The activation of the positive gonadotropin response to increasing levels of estradiol, which results in the mid cycle
gonadotrophic response.
❍ What is the relationship between the age of menarche and the onset of ovulatory cycles?
Adolescents with an early menarche at <12 years of age achieve ovulatory cycles sooner, with 50% of cycles being
ovulatory within a year of menarche. Women with later onset of menarche could take 8 to 12 years before their
cycles become fully ovulatory.
❍ When is the normal length of the menstrual cycle established?
The normal cycle length is usually established by the 6th year after menarche.
❍ What is a useful way to group the various causes of primary amenorrhea?
Based on the presence or absence of secondary sexual characteristics and female internal genitalia.
❍ List several differential diagnosis of primary amenorrhea in a patient with absent breast development and a
present uterus.
(1) Chromosomal abnormalities: 45X, 46X, mosaicism.
(2) 17 alpha hydroxylase deficiency with 46XX karyotype.
(3) Hypothalamic failure.
(4) Pituitary failure.
❍ List several differential diagnosis of primary amenorrhea in a patient with present breast development and
an absent uterus.
(1) Androgen insensitivity.
(2) Uterovaginal agenesis (Mayer-Rokitansky-Küster-Hauser syndrome).
❍ List one differential diagnosis of primary amenorrhea in a patient with absent breast development and an
absent uterus.
17 alpha hydroxylase deficiency with 46XX karyotype.