What is the primary purpose of a trigger shot in IVF protocols?

• A. To stimulate endometrial lining growth.
• B. To prevent luteal phase after ovulation.
• C. To reduce gonadotropin dose.
• D. To mature oocytes by inducing final meiosis and ovulation.

Answer: (B)

In IVF, the trigger shot is given to cause the final maturation of the egg and to induce ovulation so the eggs are ready for retrieval. It mimics the natural LH surge that resumes meiosis in the oocyte, allowing the egg to progress from its arrested state to mature (metaphase II) and to be released from the follicle for collection. Timing is crucial, typically about 34–36 hours before egg retrieval, to have mature eggs at the right moment. This is not about growing the uterine lining or reducing gonadotropin use; those aspects are managed separately in the stimulation protocol. After retrieval, luteal phase support helps maintain the uterine lining for potential implantation.