Maturation of ova in the laboratory

The goal of in vitro maturation (IVM) is to allow immature oocytes collected during egg retrieval to mature in the laboratory.

Once mature, the oocytes are fertilized with selected sperm cells. Two to five days after fertilization, the embryo is transferred into the patient’s uterus.

How does IVM work?

  • The process of in vitro maturation begins with two or three ultrasounds in order to observe the size and number of follicles in development.
  • Once the follicles have achieved the desired size, an injection of hCG (human chorionic gonadotropin) is administered to the patient. This hormone promotes the maturation of the eggs.
  • 38 hours after the hCG injection, the immature eggs are retrieved with a needle.
  • The eggs are then placed in culture medium to mature for 24 to 48 hours.
  • Once the eggs have reached maturity, they are fertilized through microinjection (ICSI). (see 3.3.5)
  • The transfer to the patient’s uterus is carried out 2 to 5 days after fertilization.

IVM may be considered for patients who have had numerous immature oocytes during egg retrieval in IVF treatment. However, it is at the doctor’s discretion whether or not to recommend IVM.