Antagonist Protocol
generalDefinition
An IVF protocol in which a GnRH antagonist (Cetrotide or Ganirelix) is added mid-stimulation to prevent premature ovulation.
In IVF Treatment
The antagonist protocol is the most commonly used today due to its flexibility and lower OHSS risk. Stimulation medications start on cycle day 2-3, and the antagonist is added around Day 5-6 or when follicles reach 14 mm.