In vitro fertilization (IVF) involves a series of carefully orchestrated steps to facilitate conception. The “trigger shot” represents a pivotal moment in the treatment cycle. This precisely timed injection is designed to prepare the eggs for retrieval, serving as a signal for their final maturation within the ovaries. Its accurate administration is considered crucial for IVF success.
The Purpose of the Trigger Shot
The trigger shot plays a significant role by mimicking the body’s natural luteinizing hormone (LH) surge, which in a typical menstrual cycle initiates ovulation. In an IVF cycle, this artificial surge instructs ovarian follicles to complete the final stage of egg development, preparing them for fertilization. The most commonly used medication is human chorionic gonadotropin (hCG), which acts similarly to LH. Gonadotropin-releasing hormone (GnRH) agonists can also be employed as a trigger, particularly in protocols aimed at reducing the risk of ovarian hyperstimulation syndrome (OHSS).
Determining Your Shot Time
The timing of the trigger shot is determined through a monitoring process. Clinics track follicle growth and hormone levels to identify the optimal moment for administration. This monitoring involves regular transvaginal ultrasounds to measure the size of the ovarian follicles. Blood tests are also conducted to assess hormone levels, such as estrogen and progesterone. The goal is for several lead follicles to reach an ideal size, generally between 16-22 millimeters in diameter, before the trigger shot is given.
Based on these measurements, the fertility team provides the patient with the exact day and time for the injection. This timing is highly individualized, ensuring that the eggs are at their peak maturity when retrieved. Patients receive specific instructions from their clinic, often down to the minute.
The Window Before Egg Retrieval
Following the trigger shot, a specific timeframe, typically 34 to 36 hours, is allowed before the egg retrieval procedure. This window is essential for the eggs to complete their final maturation. The trigger shot enables the eggs to release from the follicle walls, making them accessible for aspiration during retrieval.
This narrow window is critical because it ensures the eggs are mature while also preventing spontaneous ovulation. Administering the shot too early might lead to immature eggs, while a delay could result in premature ovulation and the loss of eggs. Deviating from this precise timing can significantly impact both the number and quality of eggs retrieved, influencing the overall success of the IVF cycle.
Administering Your Trigger Shot
The trigger shot is most commonly administered as a subcutaneous injection, just under the skin, typically in the abdomen. Patients receive detailed instructions from their clinic on how to prepare the medication and perform the injection. This includes guidance on using a new syringe and needle for each dose.
Follow the clinic’s specific instructions precisely, including the exact time for the injection. If a patient has concerns about administering the injection, misses the shot, or experiences any issues such as accidental injection into muscle or an incomplete dose, contacting their clinic immediately. The fertility team can provide guidance on next steps, which may include adjusting the retrieval time or treatment plan. Never attempt to self-correct by taking a double dose.