The whole treatment consists of two or three ultrasounds, the first performed during day 2 or 3 of the patient’s menstrual cycle and the second between days 6 and 9, in order to assess the endometrium and measure the size and number of growing follicles. The oocyte retrieval is usually performed between days 9 to 14 of the cycle. An injection of HCG (Human Chorionic synthetic follicle stimulating hormone) to mature the eggs is given approximately 36 hours prior to egg retrieval. Oocyte collection is performed under ultrasound guidance with a specially designed needle and the entire procedure takes up to 30 to 40 minutes. Then the immature oocytes are culture in maturation mediums for 24 to 48 hours. Embryo transfer is usually performed 2 to 5 days after the immature oocyte collection.