Obgyn Topic 1-8 Flashcards
- What are the bones that form the bony pelvis?
The bony pelvis consists of the paired innominate bones (ilium, ischium, and pubis), sacrum, and coccyx.
Where are the innominate bones joined anteriorly and posteriorly?
The innominate bones are joined anteriorly at the symphysis pubis and posteriorly articulate with the sacrum at the sacroiliac joints.
What happens to the joints of the bony pelvis during pregnancy?
During pregnancy, the joints relax to allow some mobility during labor and birth.
How is the bony pelvis divided?
The bony pelvis is divided into the false pelvis and the true pelvis by the pelvic brim.
What are the sections of the true pelvis?
The true pelvis is divided into three sections: the pelvic inlet, mid-pelvis, and pelvic outlet.
What are the boundaries of the pelvic inlet?
The pelvic inlet is bounded anteriorly by the superior surface of the pubic bones and posteriorly by the promontory and alae of the sacrum.
What is the mid-pelvis level?
The mid-pelvis is at the level of the ischial spines.
What are the boundaries of the pelvic outlet?
The pelvic outlet is bounded anteriorly by the lower border of the symphysis, laterally by the ischial tuberosities, and posteriorly by the tip of the sacrum.
What does the term vulva refer to?
Vulva refers to the female external genitalia, including the mons pubis, labia majora, labia minora, clitoris, external urinary meatus, vestibule of the vagina, vaginal orifice, and hymen.
What is the mons pubis composed of?
The mons pubis is composed of a fibrofatty pad of tissue above the pubic symphysis and is covered with dense pubic hair.
What are the labia majora?
The labia majora are two longitudinal cutaneous folds extending from the mons pubis to the perineum, with an outer hair-covered surface and an inner smooth layer.
What do the labia majora enclose?
The labia majora enclose the pudendal cleft, into which the urethra and vagina open.
What are the labia minora?
The labia minora are enclosed by the labia majora and divide anteriorly to enclose the clitoris, forming the prepuce and frenulum.
Where is the clitoris located and what is its structure?
The clitoris is situated between the anterior ends of the labia minora and consists of two corpora cavernosa of erectile tissue enclosed in a fibrous sheath.
What is the role of the clitoris in sexual function?
The clitoris plays an important role in sexual stimulation due to its rich supply of sensory nerve endings.
What is the vestibule in the female genitalia?
The vestibule is a shallow depression between the labia minora, with the external urethral orifice opening anteriorly and the vaginal orifice posteriorly.
Where do Bartholin’s glands drain?
Bartholin’s glands drain into the vestibule at the posterior margin.
What are Skene’s ducts?
Skene’s ducts lie alongside the lower 1cm of the urethra and drain into the vestibule.
Where is the external urethral orifice located?
The external urethral orifice lies 1.5–2 cm below the base of the clitoris and is covered by the labia minora.
What is the hymen and what happens after it is penetrated?
The hymen is a thin fold of skin covering the vaginal orifice. After penetration, its remnants form the carunculae myrtiformes, nodules of fibrocutaneous material.
Where are Bartholin’s glands located, and what is their function?
Bartholin’s glands are located on either side of the vaginal introitus, and they secrete mucus during sexual arousal.
What causes Bartholin’s cysts?
Bartholin’s cysts form due to the occlusion of the gland duct, leading to fluid accumulation in the duct.
What is the vagina and its length in a mature female?
The vagina is a muscular tube about 6-7.5 cm long in the mature female, lined by non-cornified squamous epithelium.
How does the vagina adapt during parturition?
The vagina is capable of considerable distension to accommodate the passage of the fetal head during parturition.
Where is the vagina located in relation to the anal canal, rectum, and peritoneum?
The vagina is separated from the anal canal by the perineal body, lies in apposition to the ampulla of the rectum in the middle third, and is covered by the peritoneum of the rectovaginal pouch in the upper segment.
What is the vaginal vault and what are its zones?
The vaginal vault is where the uterine cervix protrudes into the vagina, with four zones: the anterior fornix, posterior fornix, and two lateral fornices.
What is the pH of the vagina in a sexually mature, non-pregnant female and its function?
The pH of the vagina is between 4.0 and 5.0, which has an antibacterial function, reducing the risk of pelvic infection.
What are the functions of the vagina?
The functions of the vagina are copulation, parturition, and the drainage of menstrual loss.
What is the uterus, and where is it located?
The uterus is a hollow, muscular, pear-shaped organ situated in the pelvic cavity between the bladder anteriorly and the rectum and pouch of Douglas posteriorly.
What are the dimensions of the uterus in a sexually mature female?
The uterus is approximately 7.5 cm long and 5 cm wide in a sexually mature female.
What is the normal position of the uterus, and what are anteversion and retroversion?
The uterus normally lies in anteversion, with the fundus anterior to the cervix. In about 10% of women, the uterus lies in retroversion.
What are anteflexion and retroflexion of the uterus?
Anteflexion is when the uterus is curved anteriorly in its longitudinal axis, while retroflexion is when it is curved posteriorly.
What are the main parts of the uterus?
The uterus consists of the body or corpus, the isthmus, and the cervix.
What are the muscle layers of the corpus uteri?
The corpus uteri has three layers of smooth muscle cells: the external layer with transverse fibers, the middle layer arranged circularly, and the inner layer with longitudinal, circular, and oblique fibers.
What is the shape and volume of the uterine cavity in the non-pregnant state?
The uterine cavity is triangular in shape and flattened anteroposteriorly, with a total volume of approximately 2 mL.
What lines the uterine cavity?
The uterine cavity is lined by the endometrium, which consists of mucus-secreting columnar epithelium.
What is the cervix, and how does it change after vaginal birth?
The cervix is a barrel-shaped structure extending from the external cervical os to the internal cervical os. The external os is round or oval in non-parous women but becomes transverse after vaginal birth.
What is the cervical canal, and what epithelium lines it?
The cervical canal is fusiform in shape and is lined by ciliated columnar epithelium that secretes mucus.
What is the squamocolumnar junction?
The squamocolumnar junction is the transition point between the ciliated columnar epithelium of the cervical canal and the vaginal ectocervix epithelium.
What are nabothian follicles and how do they form?
Nabothian follicles form when cervical glands become obstructed.
What is the isthmus of the uterus and its role in pregnancy?
The isthmus joins the cervix to the corpus uteri and enlarges during pregnancy, contributing to the formation of the lower uterine segment.
What is the role of the isthmus during labor?
During labor, the isthmus becomes part of the birth canal but does not contribute significantly to fetal expulsion.
What does the broad ligament connect, and what does it contain?
The broad ligament connects the lateral uterus, fallopian tubes, and ovaries with the lateral pelvic wall. It contains the ovarian artery and vein, round ligament, fallopian tubes, and ovaries.
What is the role of the round ligament, and what does it connect?
The round ligament is responsible for the anteroversion-anteflexion position of the uterus. It connects the uterine horn with the labia majora and contains the lymphatics of the uterine horn.
What does the cardinal ligament connect, and what does it contain?
The cardinal ligament connects the cervix with the lateral pelvic wall and contains the uterine artery and vein and the ureter.
Where are the fallopian tubes located?
The fallopian tubes are located between the fundus of the uterus and the ovaries, lying on the posterior surface of the broad ligament.
What is the length of the fallopian tubes?
The fallopian tubes are approximately 10-12 cm long.
What encloses the fallopian tubes, and what does it contain?
The fallopian tubes are enclosed in the mesosalpinx, which contains the blood vessels and nerve supply to the tubes and ovaries.
What are the four sections of the fallopian tube?
The fallopian tube is divided into the interstitial portion, isthmus, ampulla, and infundibulum.
Where does fertilization typically occur in the fallopian tube?
Fertilization typically occurs in the ampulla, a widened section of the fallopian tube.
What lines the fallopian tubes, and what is its function?
The fallopian tubes are lined by a single layer of ciliated columnar epithelium, which assists in the movement of the oocyte.
What are the ovaries, and what are their functions?
The ovaries are paired, almond-shaped organs with both reproductive and endocrine functions.
What are the dimensions of the ovaries?
The ovaries are approximately 2.5-5 cm in length and 1.5-3.0 cm in width.
Where are the ovaries located?
The ovaries lie on the posterior surface of the broad ligament in a shallow depression known as the ovarian fossa.
What attaches the anterior border of the ovary to the broad ligament?
The anterior border of the ovary is attached to the posterior layer of the broad ligament by the mesovarium, a fold in the peritoneum.
What attaches the lower pole of the ovary to the uterus?
The lower pole of the ovary is attached to the lateral border of the uterus by the ovarian ligament.
What covers the surface of the ovary?
The surface of the ovary is covered by cuboidal or low columnar germinal epithelium.
What lies beneath the germinal epithelium of the ovary?
Beneath the germinal epithelium is a layer of dense connective tissue known as the tunica albuginea.
What are Graafian follicles, and where are they found?
Graafian follicles are found in the highly vascular, central portion of the ovary, known as the medulla.
What is the blood supply to the pelvic organs?
The blood supply to the pelvic organs is provided by the internal iliac arteries (hypogastric arteries).
What does the internal pudendal artery supply?
The internal pudendal artery supplies the perineum
What does the vaginal artery supply, and where can it arise from?
The vaginal artery supplies the anterior and posterior walls of the vagina and can also arise from the uterine artery.
What does the uterine artery supply, and what happens during pregnancy?
The uterine artery supplies the body and fundus of the uterus through its superior branch and the cervix and vagina through its cervical branch. During pregnancy, the uterine artery becomes a major vascular structure due to the increase in uterine blood flow.
Where does the ovarian artery arise from, and what does it supply?
The ovarian artery arises from the abdominal aorta, crosses the proximal end of the external iliac artery, and supplies the ovary through the suspensory ligament of the ovary.
Where do the pelvic lymphatics course and drain?
The pelvic lymphatics course along the internal iliac vessels and drain into the inferior mesenteric and aortic lymph nodes (upper part of rectum), paraaortic lymph nodes (ovaries, fallopian tubes, uterus fundus), and internal and external iliac lymph nodes (uterus body and cervix, bladder, rectum).
What do the inferior mesenteric and aortic lymph nodes drain?
They drain the upper part of the rectum.
What do the paraaortic lymph nodes drain?
They drain the ovaries, fallopian tubes, and the uterus fundus.
What do the internal and external iliac lymph nodes drain?
They drain the uterus body and cervix, bladder, and rectum.
What are the autonomic nerves of the pelvis?
The autonomic nerves of the pelvis include the superior and inferior hypogastric plexus, hypogastric nerve, sacral splanchnic nerves, and pelvic splanchnic nerves (S2-S4).
What are the functions of the pelvic splanchnic nerves?
The pelvic splanchnic nerves (S2-S4) provide parasympathetic fibers, form part of the pelvic plexus, and innervate the descending and sigmoid colon, pelvic organs, and perineum, including sexual organs.
What does the pudendal nerve (S2-S4) provide motor and sensory innervation to?
The pudendal nerve provides motor innervation to the external urethral sphincter, external anal sphincter, and levator ani. It provides sensory innervation to the perineum, clitoris, posterior labia, and anal canal.
What injury risks are associated with the pudendal nerve, and what clinical use does it have?
Injury to the pudendal nerve (e.g., during pelvic trauma or surgery) can cause urinary and fecal incontinence. It is also used for pudendal nerve block during childbirth or surgeries involving the perineum, with the ischial spine as the landmark for injection
What is the pelvic floor and its role?
The pelvic floor is a diaphragm across the outlet of the true pelvis, supporting some abdominal organs. It is important in defecation, coughing, vomiting, and parturition.
What muscles form the principal support of the pelvic floor?
The levator ani muscles, consisting of the iliococcygeus, puborectalis, and pubococcygeus muscles, form the principal support of the pelvic floor.
What is the perineum, and how is it divided?
The perineum is the region below the pelvic floor and is divided into anterior (urogenital triangle) and posterior (anal triangle) sections by a line between the ischial tuberosities.
What structures are found in the urogenital triangle of the perineum?
The urogenital triangle includes part of the urethra and the urogenital diaphragm, which is traversed by the vagina.
What structures are found in the anal triangle of the perineum?
The anal triangle includes the anus, anal sphincter, and perineal body
What passes through the lateral aspect of the fossa in the perineum?
The pudendal nerve and internal pudendal vessels pass through the lateral aspect of the fossa, enclosed in the fascial layer of Alcock’s canal.
What forms the cortex of the ovary during oogenesis?
Germ cells form sex cords that become the cortex of the ovary, which breaks up into separate clumps of cells by 16 weeks, becoming primary follicles that incorporate central germ cells.
How many oogonia are present by 20 weeks of intrauterine life?
By 20 weeks, there are approximately 7 million oogonia.
What happens to oogonia after 20 weeks of intrauterine life?
No further cell division occurs after 20 weeks, and no more ova are produced. The oogonia begin the first meiotic division, becoming primary oocytes by birth.
How does the number of primary oocytes change from birth to puberty?
By birth, there are about 1 million primary oocytes, and this number decreases to approximately 0.4 million by puberty.
What cells surround the oogonia in the cortex of the ovary?
The oogonia are surrounded by follicular cells that later develop into granulosa cells.
What characterizes the first stage of follicular development in the ovary?
The first stage is characterized by the enlargement of the ovum and the aggregation of stromal cells to form thecal cells.
When is a dominant follicle selected, and what structure forms around the ovum?
A dominant follicle is selected around day 6 of the menstrual cycle, and the innermost granulosa cells adhere to the ovum, forming the corona radiata.
What is the zona pellucida, and when does it form?
The zona pellucida is a clear layer of gelatinous material that collects around the ovum during follicular development.
What happens to the follicle after ovulation if implantation does not occur?
The corpus luteum reaches its peak about 7 days after ovulation and regresses unless implantation occurs. If not, it becomes a white scar known as the corpus albicans.
What hormone produced by an implanting embryo prolongs corpus luteum function?
β-hCG (human chorionic gonadotropin) produced by the implanting embryo prolongs corpus luteum function until the placenta takes over at about 10 weeks of gestation.
What initiates the hormonal events associated with ovulation?
The release of GnRH (gonadotropin-releasing hormone) initiates the hormonal events, resulting in the release of FSH (follicle-stimulating hormone) and LH (luteinizing hormone) from the pituitary.
How does GnRH influence LH and oestrogen levels during the menstrual cycle?
GnRH is released in episodic surges, which increase plasma LH levels just before midcycle, initiating the oestrogen-induced LH surge.
How do FSH levels change during the menstrual cycle?
FSH levels are slightly higher during menses and subsequently decline due to the negative feedback effect of oestrogen production by the dominant follicle.
When does the LH surge occur in relation to ovulation?
The LH surge occurs 35–42 hours before ovulation, accompanied by a smaller coincidental FSH peak.
What happens to LH and FSH levels in the second half of the menstrual cycle?
LH and FSH levels are slightly lower in the second half of the cycle, but continued LH release is necessary for normal corpus luteum function.
How do estrogen and progesterone levels change during the menstrual cycle?
Estrogen increases during the first half of the cycle, falls to about 60% of its follicular phase peak after ovulation, and rises again during the luteal phase.
Progesterone levels are low before ovulation but increase throughout most of the luteal phase.
What regulates the release of FSH and LH by the pituitary?
Feedback mechanisms involving estrogen and progesterone from the ovaries regulate the release of FSH and LH. In cases of ovarian failure, such as menopause, the lack of these hormones leads to elevated gonadotrophin levels.
What are the functions of FSH and LH during the menstrual cycle?
FSH stimulates follicular growth and development, specifically binding to granulosa cells. It helps the dominant follicle mature by stimulating estrogen production and inducing LH receptors in granulosa cells.
LH triggers ovulation, reactivates meiosis I in the oocyte, and supports corpus luteum development.
What happens to the follicles during a menstrual cycle?
Around 30 follicles begin to mature during each cycle, but only one dominant follicle becomes fully developed. The dominant follicle continues developing under the influence of FSH, while other follicles degenerate due to lower FSH levels.
What is the role of LH receptors in the menstrual cycle?
LH receptors are found in the theca and granulosa cells of the developing follicle and later in the corpus luteum. LH binds to these receptors to:
Trigger ovulation, allowing the oocyte to be released from the follicle.
Reactivate meiosis I in the oocyte, which had been arrested.
Sustain the development and function of the corpus luteum, which secretes progesterone to support a potential pregnancy.
Endometrial Cycle Phases
Menstrual Phase
Phase of Repair
Follicular/Proliferative Phase
Luteal/Secretory Phase
Endometrial Cycle Menstrual Phase
(Days 1-4):
The outer two layers of the endometrium (zona compacta and zona spongiosa) are shed due to the vasoconstriction of spiral arterioles, leading to necrosis. This phase is triggered by a fall in estrogen and progesterone.
Endometrial Cycle Phase of Repair
(Days 4-7):
A new capillary bed forms, and the epithelial surface regenerates. This prepares the endometrium for the next cycle.
Endometrial Cycle Follicular/Proliferative Phase
(Days 7-14):
The endometrium undergoes maximal growth, with elongation and expansion of the endometrial glands and stromal development.
This phase is driven by rising estrogen levels, which stimulate growth until ovulation.
Endometrial Cycle Luteal/Secretory Phase
(Days 15-28):
After ovulation, the endometrium becomes more glandular and secretory in response to progesterone produced by the corpus luteum. The glands become convoluted with a “saw-toothed” appearance, and there is basal vacuolation in epithelial cells.
As menstruation approaches, there is stromal edema and infiltration of leukocytes, preparing the endometrium for its shedding unless pregnancy occurs.
What is fertilization?
Fertilization is the fusion of male and female gametes to produce a diploid genetic complement from both partners.
What is sperm transport and how is it influenced by the female cycle?
Sperm migrate into the cervical mucus after semen deposition near the cervical os. Migration is facilitated by receptive mucus in mid-cycle, but during the luteal phase, the mucus is not receptive, limiting sperm access to the uterine cavity.
What is the rate of sperm migration under favorable conditions?
Sperm migrate at a rate of 6 mm per minute under favorable conditions.
What is capacitation and where does it occur?
Capacitation is the final maturation process of sperm, allowing penetration of the zona pellucida, and occurs during passage through the Fallopian tubes.
What triggers the acrosome reaction during fertilization?
The adherence of sperm to the oocyte triggers the acrosome reaction, leading to the release of lytic enzymes that help sperm penetrate the oocyte membrane.
How is the sperm head incorporated into the oocyte?
The sperm head fuses with the oocyte plasma membrane and is engulfed by phagocytosis into the oocyte, where it decondenses to form the zygote.
What happens to the conceptus 36 hours after fertilization?
The conceptus is transported through the Fallopian tube by muscular peristaltic action and undergoes cleavage. By the 16-cell stage, it becomes a solid ball of cells called the morula.
What structure forms after the morula and when does it attach to the endometrium?
A blastocyst forms after the morula, and six days after ovulation, it attaches to the endometrium, usually near the mid-portion of the uterine cavity.
What occurs by the seventh post-ovulatory day in the process of implantation?
The blastocyst penetrates deeply into the endometrium. Endometrial cells are destroyed by the cytotrophoblast, initiating the decidual reaction, where stromal cells become large and pale.
- What is the weight change of the uterus from non-pregnancy to term?
The non-pregnant uterus weighs ~40–100 g, increasing during pregnancy to 300–400 g at 20 weeks and 800-1000 g at term.
What is the structure of the uterus during pregnancy?
The uterus consists of bundles of smooth muscle cells separated by thin sheets of connective tissue composed of collagen, elastic fibers, and fibroblasts. These all hypertrophy during pregnancy.
How does myometrial growth occur during pregnancy?
Myometrial growth occurs almost entirely due to muscle hypertrophy and elongation of the cells from 5 µm in the non-pregnant state to 200–600 µm at term. This is influenced by estrogen and progesterone.
What are the three functional and morphological divisions of the uterus?
The uterus is divided into three sections:
Cervix
Isthmus
Body of the uterus (corpus uteri).
What percentage of uterine muscle cells are in the cervix?
The cervix contains only 10% of uterine muscle cells, with 80% of its total protein in the non-pregnant state consisting of collagen.
What happens to the collagen content of the cervix by the end of pregnancy?
By the end of pregnancy, the collagen concentration in the cervix is reduced to one-third of its pre-pregnancy levels.
What are the characteristic changes in the cervix during pregnancy?
The characteristic changes include:
Increased vascularity
Hypertrophy of cervical glands
Increased mucous secretion, forming an antibacterial mucus plug
Reduction in collagen, accumulation of glycosaminoglycans and water, leading to cervical ripening.
What changes occur in the isthmus of the uterus during pregnancy?
By the 28th week, regular contractions stretch and thin the isthmus, resulting in the early formation of the lower uterine segment, which is fully formed during labor.
Why is the lower uterine segment the preferred site for a caesarean delivery?
Due to its relative avascularity and quiescence in the puerperium, the lower uterine segment is the ideal site for a caesarean delivery incision.
How does the corpus uteri change during pregnancy?
The corpus uteri changes in size, shape, position, and consistency. The fundus enlarges, the round ligaments emerge from a relatively lower point, and the uterus transforms from pear-shaped to globular and ovoid.
What is the capacity of the uterine cavity at full term?
The uterine cavity expands from around 4 mL to 4000 mL at full term.
How do the uterine arteries change during pregnancy?
The uterine arteries dilate, and the arcuate arteries supplying the placental bed become 10 times larger. Spiral arterioles increase to 30 times their pre-pregnancy diameter.
How much does uterine blood flow increase during pregnancy?
Uterine blood flow increases from 50 mL/min at 10 weeks gestation to 500–600 mL/min at term.
What is the contribution of the ovarian vessels to uterine blood supply during pregnancy?
In pregnancy, 20–30% of the blood supply to the uterus is contributed by the ovarian vessels.
Clinical significance of amniotic fluid volume
