Menstrual cycle and ovulation

Before any treatment, a physician investigates a woman’s menstrual cycle. The hormonal profile is important, but the only proof of normal ovulation is an ultrasound performed a day after expected ovulation.  

Ovulation within the appropriate time frame is central for successful fertilization and pregnancy. In most cases, ovulation problems are ruled out if there are any evidences of ovulation taking place: regular cycle, absence of ovarian cysts, changes in basal temperature, or an LH surge or rising progesterone.    

However, the only conclusive way to demonstrate ovulation is an ultrasound performed after expected ovulation. Furthermore, ultrasound has to be performed 2-3 days after LH surge to be bona fide evidence of normal ovulation. This is because if the oocyte failed to ovulate within 3 days after LH surge, it may still be fertilized but will miss its optimal (viable) fertilization window and will fail to establish viable pregnancy.  Consequently, an ultrasound performed more than 3 days after LH surge will prove that ovulation took place, but will not tell whether ovulation took place within the optimal time frame. 

Strictly speaking, even evidence of ovulation 3 days after LH surge still leaves a possibility of an oocyte missing viable fertilization window, but this is the best that can realistically be done. 

This scope of information gives a physician a good view of the menstrual cycle:

  1. Duration of the cycle
  2. Duration of the period
  3. Ultrasound on day 1-3 of the cycle for antral follicles count
  4. Level of FSH on day 1-3 of the cycle
  5. Level of E2 on day 1-3 of the cycle
  6. Ultrasound on day 10-12 of the cycle (or later before ovulation) to make sure that the follicle is at the expected size. 
  7. Day of ovulation using home ovulation kits or basal temperature chart  to determine the duration of the follicular phase
  8. Ultrasound two days after the initial rise of LH (or basal temperature) to confirm that ovulation takes place within the optimal time of conception for the oocyte AND to measure the thickness of the endometrium 
  9. Progesterone level on day 5-7 after ovulation 

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