Ovulation induction is the process of using fertility medication to facilitate superovulation, i.e., the production of multiple mature eggs. For IVF, we like to obtain 10-20 total eggs, if possible. During this stage, the patient also undergoes regular ultrasounds and blood tests to measure estrogen levels and determine any ovarian cysts.
Vaginal Ultrasound
This exam indicates whether there are any cysts on the ovaries. Many cysts go away on their own. If not, the doctor can aspirate or 'collapse' them so that treatment may proceed.
Estrogen Level Blood Test
Estrogen, a primary female hormone produced by the ovaries, plays a crucial role in the reproductive cycle. During a natural menstrual cycle, estrogen levels typically increase during ovulation. At the beginning of the cycle, monitoring estrogen or Estradiol levels helps assess readiness to initiate treatment. Throughout the stimulation stage of IVF, ultrasound scans are accompanied by Estradiol blood tests to guide dosage adjustments as needed.
Ovulation Stimulating Medications
After the patient begins their menstrual period, they begin taking gonadotropin medications. These medications contain a concentrated form of the body's natural ovulation-stimulating hormone, which prompts the growth of egg-containing sacs called follicles. Typically, each follicle contains one egg. In a natural menstrual cycle, only one follicle will mature, but in an IVF cycle, anywhere from two to 30 follicles may develop, with the aim usually being around 10-20 total eggs.
Common gonadotropin medications include Gonal-F, Follistim, Bravelle, and Menopur. For patients following a protocol without Leuprolide, another medication called Ganirelix may be employed during the final 3-4 days of stimulation to prevent any LH surge and thereby prevent premature ovulation before the egg retrieval.
For the vast majority of IVF patients, the duration of gonadotropin injections (i.e., the number of days "in cycle") is about 10-12 days. During this time, patients undergo 4-5 monitoring visits, which involve ultrasound monitoring and Estradiol blood tests.
Preparing the Eggs for Ovulation and Fertilization
At each monitoring visit, the fertility doctor performs ultrasound exams and estrogen level tests to determine whether follicles are sufficiently large and eggs are mature. Once the majority of egg follicles measure between 16 and 20 mm in average diameter, patients are instructed to stop taking Leuprolide or Ganirelix and gonadotropin medications. The final step is to inject a single dose of a medication called human chorionic gonadotropin or hCG, also known as a “trigger shot,” which prompts the eggs to mature and detach from the follicle wall.
Timing of the hCG injection is critical
Because ovulation normally occurs about 40 hours after hCG injection, the egg retrieval procedure is scheduled approximately 36 hours after taking the medication. Patients are instructed to take the hCG injection precisely as directed.
Rest assured, our team will walk you through all aspects of the stimulation stage in advance to ensure you understand and are comfortable with all the instructions.