Summary Obstetric related disease

,Chapter 1 – Reproductive Basics

1 – Physiology of Reproduction

 Pregnancy hormones  B-hCG, hPL, Progesterone, Estriol
o hCG (produced by syncytiotrophoblast)
 α-subunit  Similar to FSH, LH, TSH (hence cross-reactivity on testing)
 β-subunit  Unique!
 Purpose: Maintains corpus luteum (which produces progesterone)
o ↓ progesterone:
1. Spiral artery constriction
2. Endometrial necrosis + release of prostaglandins
3. Endometrial shedding
o Placenta takes over progesterone secretion after 8-10wks
 Corpus luteum deficiency
 Treat: Vaginal progesterone (8-10wks)!
 Interpretation:
o If positive: Consider viable pregnancy
 Very high: Twins, Hydatidiform Mole, ?Down’s
 Low/Falling: Ectopic, Miscarriage
o If negative: Excludes pregnancy >2wk post-ovulation
 Takes 2wk for embryo to invade maternal capillaries within
uterus (hence 2wk for b-hCG to show up in mother’s blood)
 Uses:
o Amenorrhea (?preg)
o PV bleeding (?ectopic/miscarriage)
o Pelvic pain (?ectopic/miscarriage)
o Pelvic mass (?preg)
o Enlarged uterus (?preg)
 Trends
o Short-term
 Viable preg: Doubles every 2-3 days in early viable pregnancy
 Failing preg: Decreasing in early pregnancy
o Long-term
 Peak: 10wk (hence where hyperemesis WORST)
 Plateau: 20wk (then constant until end of pregnancy)

, o hPL (fetal growth hormone  similar to HGH and Prolactin)
 Rises throughout entire pregnancy
 Antagonises insulin  Gestational diabetes in 2nd + 3rd trimester
 Decreased levels seen in:
 Threatened abortion
 IUGR
o Progesterone (“Pro” + “Gestation”)
 Site of Production:
 Non-Preg: Corpus luteum
 <7wk preg: Corpus luteum
 8-9wk preg: Corpus luteum + Placenta
 >10wk preg: Placenta
 Purpose:
 Early Preg: Secretory endometrium ready for implantation
 Late Preg: Stabilise myometrium to prevent pre-term labour (reduces
sensitivity to oxytocin, and inhibits production of prostaglandins)
o Estriol
 Background:
 Estrogen (converted from androgens by aromatase)
o Estrone (E1)
 Production: Adipose tissue (from adrenal steroids)
 Dominant time: Post-menopause
o Estradiol (E2)
 Production: Follicle (granulosa cells)
 Dominant time: Non-pregnant reproductive years
o Estriol (E3)
 Production: Placenta
 Fetal DHEAS passes to placenta and is converted to
estriol
 Dominant time: Pregnancy (healthy endometrium)

o Typical blood panel for 16-20wk pregnant




 Notes:
o Stages: Zygote  2/4/8 cell stage  Morula  Blastocyst
 Trophoblast  Outer layer of blastocysts consisting of:
 Syncytiotrophoblast  Outer layer; secretes hCG to preserve progesterone
 Cytotrophoblast  Inner layer
 Embryoblast  Inner cell mass of blastocyst

,