Internal Structures

The internal structures include the vagina, uterus, uterine tubes, and ovaries. The vagina is a fibromuscular, collapsible tubular structure that extends from the vulva to the uterus and lies between the bladder and rectum. During the reproductive years the mucosal lining is arranged in transverse folds called rugae. These rugae allow the vagina to expand during childbirth. Estrogen deprivation that occurs after childbirth, during lactation, and at menopause causes dryness and thinness of the vaginal walls and smoothing of the rugae. Vaginal secretions are acidic (pH 4 to 5), which reduces the vagina’s susceptibility to infections. The vagina serves as a passageway for menstrual flow, as a female organ of copulation, and as a part of the birth canal for vaginal childbirth. The uterine cervix projects into a blind vault at the upper end of the vagina. Anterior, posterior, and lateral pockets called fornices surround the cervix. The internal pelvic organs can be palpated through the thin walls of these fornices.

The uterus is a muscular organ shaped like an upside-down pear that sits midline in the pelvic cavity between the bladder and the rectum above the vagina. Four pairs of ligaments support the uterus: the cardinal, uterosacral, round, and broad. Single anterior and posterior ligaments also support the uterus. The cul-de-sac of Douglas is a deep pouch, or recess, posterior to the cervix and formed by the posterior ligament.

The uterus is divided into two major parts: an upper triangular portion called the corpus and a lower cylindric portion called the cervix (Fig. 2-2). The fundus is the dome-shaped top of the uterus and is the site where the uterine tubes enter the uterus. The isthmus (lower uterine segment) is a short, constricted portion that separates the corpus from the cervix.

The uterus serves many purposes. It receives and implants the fertilized ovum and nourishes it throughout the pregnancy. During childbirth, the uterus is responsible for the expulsion of the fetus. It also is the organ for cyclic menstruation.

The uterine wall consists of three layers: the endometrium, the myometrium, and part of the peritoneum. The endometrium is a highly vascular lining made up of three layers, the outer two of which are shed during menstruation. The myometrium is made up of layers of smooth muscles that extend in three different directions (longitudinal, transverse, and oblique) (Fig. 2-3). Longitudinal fibers of the outer myometrial layer are mostly in the fundus, and this arrangement assists in expelling the fetus during the birth process. The middle layer contains fibers from all three directions, which form a figure-eight pattern encircling large blood vessels. This arrangement assists in constricting blood vessels after childbirth and controls blood loss. Most of the circular fibers of the inner myometrial layer are around the site where the uterine tubes enter the uterus and around the internal cervical os (opening). These fibers help keep the cervix closed during pregnancy and prevent menstrual blood from flowing back into the uterine tubes during menstruation.

The cervix is made up of mostly fibrous connective tissues and elastic tissue, enabling it to stretch during vaginal childbirth. The opening between the uterine cavity and the canal that connects the uterine cavity to the vagina (endocervical canal) is the internal os. The narrowed opening between the endocervix and the vagina is the external os, a small circular opening in women who have never been pregnant. The cervix feels firm (similar to the end of a nose) with a dimple in the center, which marks the external os.

The outer cervix is covered with a layer of squamous epithelium. The mucosa of the cervical canal is covered with columnar epithelium and contains numerous glands that secrete mucus in response to ovarian hormones. The squamocolumnar junction, where the two types of cells meet, is usually just inside the cervical os. This junction is also called the transformation zone and is the most common site for neoplastic changes. Cells from this site are scraped for the Papanicolaou (Pap) test (or smear) (see p. 51).

The uterine (fallopian) tubes attach to the uterine fundus. Broad ligaments support these tubes that range from 8 to 14 cm in length. The uterine tubes provide a passage between the ovaries and the uterus for the passage of the ovum.

The ovaries are almond-shaped organs located on each side of the uterus below and behind the uterine tubes. During the reproductive years, they are approximately 3 cm long, 2 cm wide, and 1 cm thick. They diminish in size after menopause. The two functions of the ovaries are ovulation and production of estrogen, progesterone, and androgen.

Bony Pelvis

The bony pelvis serves three primary purposes: protection of the pelvic structures, accommodation of the growing fetus during pregnancy, and anchorage of the pelvic support structures. Two innominate (hip) bones (consisting of the ilium, ischium, and pubis), the sacrum, and the coccyx make up the four bones of the pelvis (Fig. 2-4). Cartilage and ligaments form the symphysis pubis, sacrococcygeal, and two sacroiliac joints that separate the pelvic bones. The pelvis is divided into two parts: the false pelvis and the true pelvis (Fig. 2-5). The false pelvis is the upper portion above the pelvic brim or inlet. The true pelvis is the lower curved bony canal, which includes the inlet, the cavity, and the outlet through which the fetus passes during vaginal birth. Variations that occur in the size and shape of the pelvis are usually a result of age, race, and injury. Pelvic ossification is complete by approximately 20 years of age.

Breasts

The breasts are paired mammary glands located between the second and sixth ribs (Fig. 2-6). Approximately two thirds of the breast overlies the pectoralis major muscle, between the sternum and midaxillary line, with an extension to the axilla referred to as the tail of Spence. The lowest third of the breast lies over the serratus anterior muscle. Connective tissue called fascia attach the breast to the muscles.

The breasts of healthy mature women are approximately equal in size and shape but are often not absolutely symmetric. The size and shape vary depending on the woman’s age, heredity, and nutrition. However, the contour should be smooth with no retractions, dimpling, or masses. Estrogen stimulates growth of the breast by inducing fat deposition in the breasts, development of stromal tissue (i.e., an increase in its amount and elasticity), and growth of the extensive ductile system. Estrogen also increases the vascularity of breast tissue. The increase in progesterone at puberty causes maturation of mammary gland tissue, specifically the lobules and acinar structures. During adolescence, fat deposition and growth of fibrous tissue contribute to the increase in the gland’s size.

Findings from several studies using ultrasound imaging to investigate the anatomy of the breast found differences from previous descriptions (Geddes, 2007; Love & Barsky, 2004; Ramsay, Kent, Hartmann, & Hartmann, 2005). Each mammary gland is made of a number of lobes, which are divided into lobules. Lobules are clusters of acini. An acinus is a saclike terminal part of a compound gland emptying through a narrow lumen or duct. The acini are lined with epithelial cells that secrete colostrum and milk. Just below the epithelium is the myoepithelium (myo, or muscle), which contracts to expel milk from the acini.

The ducts from the clusters of acini that form the lobules merge to form larger ducts draining the lobes. Ducts from the lobes converge in a single nipple (mammary papilla) surrounded by an areola. The anatomy of the ducts is similar for each breast but varies among women. Protective fatty tissue surrounds the glandular structures and ducts. Cooper’s ligaments, or fibrous suspensory, separate and support the glandular structures and ducts. Cooper’s ligaments provide support to the mammary glands while permitting their mobility on the chest wall (see Fig. 2-6). The round nipple is usually slightly elevated above the breast. On each breast the nipple projects slightly upward and laterally. It contains 4 to 20 openings from the milk ducts. The nipple is surrounded by fibromuscular tissue and covered by wrinkled skin (the areola). Except during pregnancy and lactation, there is usually no discharge from the nipple.

The nipple and surrounding areola are usually more deeply pigmented than the skin of the breast. Sebaceous glands called Montgomery tubercles directly beneath the skin (see Fig. 2-6) give the areola its rough appearance. These glands secrete a fatty substance thought to lubricate the nipple.

The vascular supply to the mammary gland is abundant. The skin covering the breasts contains an extensive superficial lymphatic network that serves the entire chest wall and is continuous with the superficial lymphatics of the neck and abdomen. In the deeper portions of the breasts, the lymphatics form a rich network as well. The primary deep lymphatic pathway drains laterally toward the axillae.

The breasts change in size and nodularity in response to cyclic ovarian changes throughout reproductive life. Increasing levels of both estrogen and progesterone in the 3 to 4 days before menstruation increase vascularity of the breasts, induce growth of the ducts and acini, and promote water retention. As a result, breast swelling, tenderness, and discomfort are common symptoms just before the onset of menstruation. After menstruation, cellular proliferation begins to regress, acini begin to decrease in size, and retained water is lost. In time, after repeated hormonal stimulation, small persistent areas of nodulations may develop just before and during menstruation, when the breast is most active. The physiologic alterations in breast size and activity reach their minimal level approximately 5 to 7 days after menstruation stops. The best time for a woman who wishes to perform a breast self-examination (BSE) is during this phase of the menstrual cycle or whenever the breasts are not tender or swollen (see Patient Instructions for Self-Management box).

Patient Instructions for Self-Management

Breast Self-Examination

If you choose to perform a breast self-examination, the best time is when breasts are not tender or swollen.

How to examine your breasts:

1. Lie down and put a pillow under your right shoulder. Place your right arm behind your head (Fig. 1).

2. Use the finger pads of your three middle fingers on your left hand to feel for lumps or thickening. Your finger pads are the top third of each finger. Use circular motions of the finger pads to feel the breast tissue.

3. Press firmly enough to know how your breast feels. Use light pressure to feel the tissue just under the skin, medium pressure for a little deeper, and firm pressure to feel the breast tissue close to the chest and ribs. A firm ridge in the lower curve of the breast is normal.

4. Move around the breast in a set way, such as using an up and down or vertical line pattern (Fig. 2). Go up to the collar bone and down to the ribs and from your underarm on the side to the middle of your chest. Use the same technique every time. It will help you to make sure that you have gone over the entire breast area and to remember how your breast feels.

5. Now examine your left breast using the finger pads of your right hand.

6. You may want to check your breasts while standing in front of a mirror. See if there are any changes in the way your breasts look: dimpling of the skin, changes in the nipple, or redness or swelling.

7. You may also want to perform an extra breast self-examination while you are in the shower (Fig. 3). Your soapy hands will glide over the wet skin, making it easy to check how your breasts feel.

8. Checking the area between the breast and the underarm and the underarm itself is important. Examine the area above the breast to the collarbone and to the shoulder while you are standing or sitting up with your arms lightly raised.

9. If you find any changes, see your health care provider right away.

Source: American Cancer Society. (2008). How to perform a breast self-exam. Internet document available at www.cancer.org (accessed June 4, 2009).

Menstruation

Menstrual cycle

Initially, menstrual periods are irregular, unpredictable, painless, and anovulatory. After the ovary produces adequate cyclic estrogen to make a mature ovum, periods tend to be regular and ovulatory. The menstrual cycle is a complex interplay of events that occur simultaneously in the endometrium, hypothalamus and pituitary glands, and ovaries. The menstrual cycle prepares the uterus for pregnancy. When pregnancy does not occur, menstruation follows. Menstruation is the periodic uterine bleeding that begins approximately 14 days after ovulation. The average length of a menstrual cycle is 28 days, but variations are common. The first day of bleeding is designated as day 1 of the menstrual cycle, or menses (Fig. 2-7). The average duration of menstrual flow is 5 days (range of 1 to 8 days), and the average blood loss is 50 ml (range of 20 to 80 ml), but these vary greatly (Fehring, Schneider, & Raviele, 2006). The woman’s age, physical and emotional status, and environment also influence the regularity of her menstrual cycles.

Hypothalamic-pituitary cycle.

Toward the end of the normal menstrual cycle, blood levels of estrogen and progesterone fall. Low blood levels of these ovarian hormones stimulate the hypothalamus to secrete gonadotropin-releasing hormone (GnRH). In turn, GnRH stimulates anterior pituitary secretion of follicle-stimulating hormone (FSH) that stimulates development of ovarian graafian follicles and their production of estrogen. Estrogen levels begin to fall, and hypothalamic GnRH triggers the anterior pituitary release of luteinizing hormone (LH). A marked surge of LH and a smaller peak of estrogen (day 12; see Fig. 2-7) precede the expulsion of the ovum (ovulation) from the graafian follicle by approximately 24 to 36 hours. LH peaks at approximately the thirteenth or fourteenth day of a 28-day cycle. If fertilization and implantation of the ovum do not occur by this time, the corpus luteum regresses. Levels of progesterone and estrogen decline, menstruation occurs, and the hypothalamus is once again stimulated to secrete GnRH. This process is the hypothalamic-pituitary cycle.

Ovarian cycle.

 Animation: Ovaries

 Animation: Ovarian Cycle

 Animation: Ovulation

The primitive graafian follicles contain immature oocytes (primordial ova). Before ovulation, from 1 to 30 follicles begin to mature in each ovary under the influence of FSH and estrogen. The preovulatory surge of LH affects a selected follicle. The oocyte matures, ovulation occurs, and the empty follicle begins its transformation into the corpus luteum. This follicular phase (preovulatory phase) (see Fig. 2-7) of the ovarian cycle varies in length from woman to woman and accounts for almost all variations in ovarian cycle length (Fehring et al., 2006). On rare occasions (approximately 1 in 100 menstrual cycles), more than one follicle is selected and more than one oocyte matures and undergoes ovulation.

After ovulation, estrogen levels drop. For 90% of women, only a small amount of withdrawal bleeding occurs, so it goes unnoticed. In 10% of women bleeding is sufficient for it to be visible, resulting in what is known as midcycle bleeding.

The luteal phase begins immediately after ovulation and ends with the start of menstruation. This postovulatory phase of the ovarian cycle usually requires 14 days (range of 13 to 15 days). The corpus luteum reaches its peak of functional activity 8 days after ovulation, secreting both estrogen and progesterone. Coincident with this time of peak luteal functioning, the fertilized ovum is implanted in the endometrium. If no implantation occurs, the corpus luteum regresses, steroid levels drop, and menstruation occurs.

Endometrial cycle.

The endometrial cycle is divided into four phases (see Fig. 2-7). During the menstrual phase, shedding of the functional two thirds of the endometrium (the compact and spongy layers) is initiated by periodic vasoconstriction in the upper layers of the endometrium. The basal layer is always retained, and regeneration begins near the end of the cycle from cells derived from the remaining glandular remnants or stromal cells in the basalis.

The proliferative phase is a period of rapid growth lasting from approximately the fifth day to the time of ovulation. The endometrial surface is completely restored in approximately 4 days, or slightly before bleeding ceases. From this point on, an eightfold to tenfold thickening occurs, with a leveling off of growth at ovulation. The proliferative phase depends on estrogen stimulation derived from ovarian follicles.

The secretory phase extends from the day of ovulation to approximately 3 days before the next menstrual period. After ovulation, larger amounts of progesterone are produced. The fully matured secretory endometrium reaches the thickness of heavy, soft velvet. It becomes luxuriant with blood and glandular secretions, a suitable protective and nutritive bed for a fertilized ovum.

Implantation of the fertilized ovum generally occurs approximately 7 to 10 days after ovulation. If fertilization and implantation do not occur, the corpus luteum, which secretes estrogen and progesterone, regresses. With the rapid fall in progesterone and estrogen levels, the spiral arteries go into spasm. During the ischemic phase, the blood supply to the functional endometrium is blocked, and necrosis develops. The functional layer separates from the basal layer, and menstrual bleeding begins, marking day 1 of the next cycle (see Fig. 2-7).

Other cyclic changes.

When the hypothalamic-pituitary-ovarian axis functions properly, other tissues undergo predictable responses. Before ovulation the woman’s basal body temperature (BBT) is often below 37° C; after ovulation, with rising progesterone levels, her BBT rises. Changes in the cervix and cervical mucus follow a generally predictable pattern. Preovulatory and postovulatory mucus is viscous (thick), so sperm penetration is discouraged. At the time of ovulation, cervical mucus is thin and clear. It appears, feels, and stretches like egg white. This stretchable quality is termed spinnbarkeit. Some women experience localized lower abdominal pain, termed mittelschmerz, that coincides with ovulation.

Climacteric.

The climacteric is a transitional phase during which ovarian function and hormone production decline. This phase spans the years from the onset of premenopausal ovarian decline to the postmenopausal time when symptoms stop. Menopause refers to the last menstrual period. Unlike menarche, however, menopause can be dated only with certainty 1 year after menstruation ceases. The average age at natural menopause is 51 to 52 years, with an age range of 35 to 60 years. Menopause is preceded by a period known as the perimenopause, during which ovarian function declines. Ova slowly diminish, and menstrual cycles are anovulatory, resulting in irregular bleeding; the ovary stops producing estrogen, and eventually menses no longer occurs. This period lasts approximately 5 years (range 2-8 years) (Speroff & Fritz, 2005).

Prostaglandins

Prostaglandins (PGs) are oxygenated fatty acids classified as hormones. The different kinds of PGs are distinguished by letters (PGE, PGF), numbers (PGE₂), and letters of the Greek alphabet (PGF_2α). PGs are produced in most organs of the body, most notably by the endometrium. Menstrual blood is a potent PG source. PGs affect smooth-muscle contractility and modulation of hormonal activity. Indirect evidence supports the effects of PGs on ovulation, fertility, and changes in the cervix and cervical mucus that affect receptivity to sperm, tubal and uterine motility, sloughing of endometrium (menstruation), onset of abortion (spontaneous and induced), and onset of labor (term and preterm).

Sexual Response

The hypothalamus and anterior pituitary gland in females regulate the production of FSH and LH. The target tissue for these hormones is the ovary, which produces ova and secretes estrogen and progesterone. A feedback mechanism involving hormone secretion from the ovaries, hypothalamus, and anterior pituitary aids in the control of the production of sex cells and steroid sex hormone secretion.

Sexual stimulation results in vasocongestion (congestion of blood vessels, usually venous) that causes vaginal lubrication and engorgement and distention of the genitals. This venous congestion occurs to a lesser degree in the breasts and other parts of the body. Arousal is characterized by myotonia (increased muscular tension), resulting in voluntary and involuntary rhythmic contractions. Examples of sexually stimulated myotonia are pelvic thrusting, facial grimacing, and spasms of the hands and feet (carpopedal spasms).

The sexual response cycle is divided into four phases: excitement phase, plateau phase, orgasmic phase, and resolution phase. The four phases occur progressively, with no sharp dividing line between any two phases. Specific body changes take place in sequence. The time, intensity, and duration for cyclic completion also vary for individuals and situations. Table 2-1 compares male and female body changes during each of the four phases of the sexual response cycle.

Preconception Counseling

Preconception health promotion provides women and their partners with information that is needed to make decisions about their reproductive future. Preconception counseling guides couples on how to prevent unintended pregnancies, stresses risk management, and identifies healthy behaviors that promote the well-being of the woman and her potential fetus (Moos, 2006).

All providers who treat women for well-woman care or other routine care should incorporate preconception health screening as part of the routine care for women of reproductive age (Johnson et al., 2006). The initiation of activities that promote healthy mothers and babies must occur before the period of critical fetal organ development, which is between 17 and 56 days after fertilization. By the end of the eighth week after conception and certainly by the end of the first trimester, any major structural anomalies in the fetus are already present. Because many women do not realize that they are pregnant and do not seek prenatal care until well into the first trimester, the rapidly growing fetus may be exposed to many types of intrauterine environmental hazards during this most vulnerable developmental phase.

Preconception care is important for women who have had a problem with a previous pregnancy (e.g., miscarriage, preterm birth). Although causes are not always identifiable, in many cases, problems can be identified and treated and may not recur in subsequent pregnancies. Preconception care is also important to minimize fetal malformations. For example, the woman may be exposed to teratogenic agents such as drugs, viruses, and chemicals, or she may have a genetically inherited disease. Preconception counseling can educate the woman about the effects of these agents and diseases, which can help prevent harm to the fetus or allow the woman to make an informed decision about her willingness to accept potential hazards should a pregnancy occur (Atrash, Johnson, Adams, Cordero, & Howse, 2006).

A model for preconception care of women of reproductive age targets all women from menarche to menopause at every encounter, not just in maternity and women’s health. Providing optimal health care for women whether or not they desire to conceive can result in a high level of preconception wellness (Moos, 2006). Suggested components of preconception care, such as health promotion, risk assessment, and interventions, are outlined in Box 2-1.

Pregnancy

A woman’s entry into health care is often associated with pregnancy, either for diagnosis or for actual care. Suspicion of pregnancy occurs most commonly when a woman is late with her menses. A woman should enter prenatal care within the first 12 weeks of pregnancy; this allows for early pregnancy counseling, especially for the woman who has had no preconception care. Extensive discussion of pregnancy is found in Unit Two.

Well-Woman Care

Current trends in the health care of women have expanded beyond a reproductive focus. A holistic approach to women’s health care includes a woman’s health needs throughout her lifetime. This view is one that goes beyond simply her reproductive needs. Women’s health assessment and screening focus on a multisystem evaluation emphasizing the maintenance and enhancement of wellness.

Fertility Control and Infertility

Almost half of the pregnancies in the United States each year are unintended even with birth control use (Trussell, 2007). Education is the key to encouraging women to make family planning choices based on preference and actual risk-to-benefit ratios. Women who enter the health care system seeking contraceptive counseling can be assisted to use a chosen method correctly (see Chapter 4 for further discussion).

Women also enter the health care system because of their desire to achieve a pregnancy. Approximately 15% of couples in the United States have some degree of infertility. Infertility can cause emotional pain for many couples, and the inability to produce an offspring sometimes results in feelings of failure and inordinate stress on the relationship. Steps toward prevention of infertility should be undertaken as part of ongoing routine health care, and such information is especially appropriate in preconception counseling. For additional information about infertility, see Chapter 4.

Menstrual Problems

Irregularities or problems with the menstrual period are among the most common concerns of women and often cause them to seek help within the health care system. Common menstrual disorders include amenorrhea, dysmenorrhea, premenstrual syndrome, endometriosis, and menorrhagia or metrorrhagia. These problems are discussed in Chapter 3.

Perimenopause

Although fertility is greatly reduced during the perimenopausal period, women are urged to maintain some method of birth control because pregnancies can still occur. Most women seeking health care at this time do so because of irregular bleeding that may accompany the perimenopause. Others are concerned about vasomotor symptoms (hot flashes and flushes). All women need to have factual information, the dispelling of myths, a thorough examination, and periodic health screenings.