OB-GYN MCQs: Pregnancy and Delivery

History and Examination in OB-GYN

• The expected date of delivery (EDD) of a human pregnancy can be calculated as 40 weeks after the last menstrual period (LMP) or 280 days from the LMP.
• The last menstrual period (LMP) is used to calculate the EDD, and it is usually around 14 days after ovulation.

Anatomy of the Female Genital Tract, Bony Pelvis, and Fetal Skull

• The uterine cervix is the portion of the uterus below the isthmus, and its external OS cell lining is columnar epithelium.
• The main support of the uterus is provided by the cardinal ligament.
• The most important muscle in the pelvic floor is the levator ani.
• The pelvis includes the ilium, ischium, pubis, sacrum, and coccyx bones.
• The joint between the two pubic bones is called the pubis symphysis.
• The greatest diameter of the fetal head is the occipitomental diameter.

Labor and Fetal Surveillance and Mechanism of Labor

• Hyperextension of the fetal head is found in face presentation.
• The stages of labor include:
  • First stage: from onset of labor to full dilation of the cervix
  • Second stage: from full dilation of the cervix to delivery of the fetus
  • Third stage: from delivery of the fetus to delivery of the placenta and membranes
• A pelvis favorable to vaginal delivery has:
  • A sacral promontory that cannot be felt
  • An obstetric conjugate of more than 10 cm
  • Ischial spines that are not prominent
  • A subpubic arch that accepts 2 fingers
  • An intertuberous diameter that accepts 4 knuckles
• The fetal head follows the pelvic axis, which is a curved line, first directed anteriorly then caudal.
• Engagement is strictly defined as when the greatest biparietal diameter of the fetal head passes the pelvic inlet.
• The relationship of the fetal parts to one another determines the presentation of the fetus.
• The relationship of the long axis of the fetus to the long axis of the mother is called the lie.
• The fetal head may undergo changes in shape during normal delivery due to molding.

Embryology of Female Genital Tract, Malformations, Intersexuality, and Puberty

• In a bicornuate uterus, complications during pregnancy can include polyhydramnios, abortion, preterm labor, and abnormal fetal lie.
• In Turner's syndrome:
  • The karyotype is 45 XO
  • The ovaries are streak
  • The condition presents with primary amenorrhea
  • The girls are of short stature
  • The nipple are widely spaced
  • The condition can be diagnosed by chromosomal analysis
• In Androgen Insensitivity Syndrome:
  • The karyotype is 46 XY
  • The phenotype is female
  • The breast are usually well developed
  • The ovaries are absent
  • The condition presents with primary amenorrhea
  • The testes are usually present in the inguinal area### Developmental Anomalies
• Gonadectomy should be performed after puberty due to increased risk of malignancy
• Estrogen replacement therapy is not necessary in cases of bicornuate uterus, as the individual has enough estrogens to produce breast development

Bicornuate Uterus

• Associated with increased risk of congenital anomalies in the urinary system
• Can cause abortions, abnormal fetal lie, infertility, and retained placenta, but not congenital anomalies of the baby

Turner's Syndrome

• Characterized by:
  • Streak ovaries that should be removed surgically due to 25% tendency to be malignant
  • Short stature (less than 5 feet tall)
  • Raised FSH levels
  • Female internal genitalia
  • Normal but infertile external genitalia
• Diagnosis is best confirmed by chromosomal analysis (karyotyping)

Adnexa Uteri

• Include ovaries, fallopian tubes, and broad ligament, but not round ligament

Development of External Genitalia

• Genital tubercles form labia minora
• Genital swelling forms labia majora
• Genital fold forms scrotum in males
• Dihydrotestosterone is essential for muscularity of external genitalia

Congenital Uterine Malformations

• Can cause spontaneous abortions, premature labor, pregnancy-induced hypertension, and abnormal fetal lie, but not obstructed labor

Ovarian Dysgenesis

• Associated with elevation of pituitary gonadotropins

Androgen Insensitivity Syndrome

• Characterized by:
  • Chromosomal sex of 46 XX
  • Scant or no pubic or axillary hair
  • No uterus
  • Normal female external genitalia
  • Breast development is usually normal

Testicular Feminization Syndrome

• Characterized by:
  • Normal testes
  • Breast development is usually present
  • Low testosterone levels
  • Karyotype is 46 XY

Turner's Syndrome

• Characterized by:
  • Underdeveloped ovaries
  • Widely spaced nipples
  • Short stature
  • Webbed neck
  • Diagnosis can be confirmed by chromosomal analysis

Development of Internal Genital Organs

• Uterus, fallopian tubes, cervix, and upper vagina develop from the mesonephric duct
• Testes secrete testosterone, which causes regression of the Müllerian ducts in the male fetus
• Vagina is formed by the urogenital sinus
• Müllerian agenesis is characterized by the absence of the uterus and upper vagina with normal female external genitalia and 46 XX

Puberty

• Transitional period of development during which an individual matures from childhood to sexual and reproductive maturity
• Breast budding is the first visible sign of puberty
• Maximum growth velocity occurs at 12 years
• Age of menarche has decreased over the last 3-4 decades due to improved nutrition, general health, and lifestyle changes
• Thelarche marks the attainment of reproductive maturity

Turner's Syndrome

• Associated with:
  • Absent uterus
  • Primary amenorrhea
  • Normal height
  • Normal breast development

Uterine Anomalies

• Associated with:
  • Urinary tract abnormalities
  • Recurrent pregnancy loss
  • Preterm labor
  • Müllerian tract anomalies
  • Polycystic ovary

Endocrine Influences

• First endocrine influence in 2nd sexual characters is the secretion of delta-4 androstenedione from the adrenal gland
• Follicular growth is usually followed by ovulation, cyst formation, atresia, or arrest
• Normal sequence of pubertal changes in the female is thelarche, maximal growth velocity, and menarche

Barr Body

• Is the condensed nonfunctioning X chromosome
• Found only in females

Precocious Puberty

• Most common cause is idiopathic
• Can be caused by gonadoblastoma, Albright syndrome, and abnormal skull development

Physiology of Menstrual Cycle

• Ovulation is suggested by:
  • Basal body temperature drop of at least 0.5°C in the second half of the cycle
  • Elevated estrogen levels on day 21
  • Elevated progesterone levels on day 10 of the cycle
• Luteal phase is associated with:
  • High progesterone levels
  • High basal body temperature
• Follicular phase is characterized by:
  • Endometrial gland proliferation
  • High estrogen levels
• Estrogen hormone is produced from the corpus luteum, placenta, and adrenal glands
• Midcycle LH surge:
  • Enhances thecal cell androgen production
  • Luteinizes granulosa cells
  • Initiates resumption of meiosis
• Involuting corpus luteum becomes a hyalinized mass known as a corpus albicans
• Best method to predict the occurrence of ovulation is by detecting LH surge

Multiple choice questions on obstetrics and gynecology, including calculating expected delivery dates and performing patient examinations.