The antagonist protocol begins directly with stimulation on the second day of the cycle, where an ultrasound is performed to check the ovarian state. During the stimulation period the scans and blood tests (measurement of estradiol and LH) and based on the findings, the simultaneous administration of an antagonist (Orgalutran, Cetrotide) to prevent premature ovulation starts at a certain day. Egg collection usually takes place on the 12th to 14th day.
The advantages of this protocol are that it is more patient friendly, simple, lasts less and presents a lower risk of overstimulation. Perhaps the only disadvantage is that in certain categories of patients such as those with a history of endometriosis, it has slightly lower success rates.
