trigger shot
An injection of hCG or GnRH agonist administered to induce final oocyte maturation and ovulation timing during fertility treatment.
Full Definition
The trigger shot is a precisely timed injection given during ovarian stimulation cycles to induce final oocyte maturation and control the timing of ovulation. Human chorionic gonadotropin (hCG) is most commonly used, mimicking the natural luteinizing hormone surge, though GnRH agonists may be used in patients at risk of OHSS. The trigger shot is typically administered when lead follicles reach 18-20mm in diameter, and egg retrieval is scheduled 34-36 hours later. Proper timing of the trigger shot is crucial for oocyte maturity and successful retrieval.
Usage
Usage note: Always specify the exact timing and type of trigger medication used.
In Context
- "The trigger shot will be administered tonight at 9 PM for retrieval on Thursday morning." — IVF cycle instruction
- "A dual trigger protocol was used combining hCG and GnRH agonist." — Stimulation cycle summary