Dysfunctional Uterine Bleeding

Dysfunctional Uterine Bleeding

Normal Menstruation

• Results from fluctuations in the circulating levels of estrogen and progesterone.
• Estrogen causes increased blood flow to the endometrium
• A significant correlation exists between plasma Estradiol and endometrial blood flow, with both increasing in the days preceding ovulation.
• These vasodilatory and vasoconstrictive effects are mediated by substances like:
  • acetylcholine
  • vasopressin
  • endothelin
  • histamine
• Estradiol and progesterone levels decrease several days prior to the onset of menses.
  • Endometrial blood flow decreases
  • Endometrial height decreases and vascular stasis occurs.
  • Tissue ischemia occurs.
  • Arterial relaxation
  • Sloughing of the endometrium.
  • Uterine bleeding occurs
• In women with DUB secondary to anovulation, endometrial blood flow is variable and follows no orderly pattern

Cessation of Menses

• Two main mechanisms:
  • Formation of the platelet plug
    • important in the functional endometrium
  • Prostaglandin dependent vasoconstriction
    • important in the basalis layer