The Roles of Follistim and the Trigger Shot
During fertility treatments like IVF, a patient's cycle is carefully controlled with medications to maximize the number of mature eggs produced. This process involves two distinct and sequential phases: ovarian stimulation and final maturation. Understanding the specific function of each medication explains why you must stop one before the other begins.
The Purpose of Follistim (Follitropin Beta)
Follistim, or follitropin beta, is a synthetic form of follicle-stimulating hormone (FSH). It is the primary medication used during the ovarian stimulation phase of an IVF cycle. Its role is to encourage the ovaries to produce and develop multiple follicles, each containing an immature egg. For approximately 8 to 14 days, a patient administers daily injections of Follistim to promote this follicular growth. Throughout this phase, a fertility specialist closely monitors the development of the follicles using ultrasound and blood tests to measure estradiol levels. This monitoring helps determine the optimal moment to proceed to the next stage.
The Action of the Trigger Shot
Once a sufficient number of follicles have reached the appropriate size, the ovarian stimulation phase is complete. The trigger shot is then administered to induce the final maturation of the eggs. This injection typically contains human chorionic gonadotropin (hCG), which mimics the body's natural luteinizing hormone (LH) surge. This LH-like signal causes the eggs to detach from the follicle walls, preparing them for retrieval. The timing of this shot is critically important and is scheduled precisely 34 to 36 hours before the planned egg retrieval procedure.
Why Follistim is Not Continued After the Trigger Shot
As a rule of thumb, you do not continue Follistim after trigger shot administration. The transition from Follistim to the trigger shot signifies a shift from the stimulation phase to the final maturation phase. Continuing Follistim would be counterproductive for several reasons.
1. The Hormonal Shift: The trigger shot's purpose is to act as the final hormonal signal, replacing the need for additional FSH. Administering both simultaneously or continuing Follistim after the trigger would be redundant. Follistim stimulates growth, while the trigger shot prompts the final release. Once the signal for release is given, further growth stimulation is not required.
2. Risk of Ovarian Hyperstimulation Syndrome (OHSS): The primary risk associated with overstimulating the ovaries is Ovarian Hyperstimulation Syndrome (OHSS). Continuing FSH injections, like Follistim, after the trigger shot could worsen this risk. Fertility clinics closely monitor for signs of OHSS and will withhold or adjust medications if necessary to prevent it. By stopping Follistim at the trigger, the patient's risk profile is managed more effectively.
3. Optimized Timing for Egg Retrieval: The 36-hour timing between the trigger shot and egg retrieval is carefully calculated to ensure the eggs are at their optimal maturity. Administering extra medication could disrupt this delicate schedule and potentially compromise the quality or quantity of eggs retrieved. Following the exact instructions from your fertility clinic is paramount for a successful outcome.
Standard Fertility Medication Protocol: A Comparison
| Feature | Follistim (FSH) | Trigger Shot (hCG/GnRH agonist) |
|---|---|---|
| Purpose | Stimulate follicular growth and maturation over several days. | Induce final egg maturation and ovulation. |
| Hormone Type | Follitropin beta, a recombinant FSH. | Human chorionic gonadotropin (hCG) or GnRH agonist (Lupron). |
| Timing | Administered daily for 8–14 days during the stimulation phase. | A single, precisely timed injection, typically ~36 hours before retrieval. |
| Frequency | Daily injections. | One-time injection per cycle. |
| Continuation After Trigger? | No, discontinue all FSH shots. | Not applicable; it is the final shot of the stimulation phase. |
The Standard Timeline
- Baseline Appointment: A fertility specialist confirms the patient is ready to begin a cycle with an ultrasound and bloodwork.
- Ovarian Stimulation: The patient begins daily injections of FSH, such as Follistim. The dosage may be adjusted based on monitoring.
- Monitoring: The clinic performs regular ultrasounds and blood tests to track follicle growth and estrogen levels.
- Trigger Determination: Once the follicles reach the appropriate size, the doctor gives the patient a specific time to administer the trigger shot. All FSH injections, including Follistim, stop at this time.
- Trigger Administration: The patient takes the trigger shot at the designated time.
- Egg Retrieval: Approximately 36 hours later, the egg retrieval procedure takes place.
Important Considerations and Next Steps
While the protocol of stopping Follistim after the trigger shot is standard, there are always variations and individual patient circumstances to consider. Always adhere strictly to the schedule and instructions provided by your fertility clinic. They are best equipped to make decisions based on your specific health and treatment response. Any remaining medication should be stored as instructed or discarded, not used without explicit instruction. The conclusion of your stimulation phase is a significant milestone in your treatment. Following the instructions for the trigger shot precisely will ensure the best possible outcome for your cycle.
Conclusion
In summary, the question of whether you continue Follistim after the trigger shot is definitively answered with a "no." The Follistim injections are a key component of the ovarian stimulation phase, but their purpose is fulfilled once the final trigger shot is given. The trigger shot, whether hCG or a GnRH agonist, takes over to prompt final egg maturation. Strictly following your clinic's timeline for stopping Follistim is not only standard protocol but also critical for mitigating risks like OHSS and maximizing the success of your egg retrieval. If any uncertainty arises regarding your medication schedule, contact your fertility team immediately for clarification. Read more on the critical timing of the IVF trigger shot.
What to Do If You Forgot to Stop Follistim
If a patient accidentally administers Follistim after the trigger shot, they should immediately contact their fertility clinic. While a single mistaken dose is unlikely to ruin the cycle, the clinic needs to be aware to monitor for potential side effects and determine if any changes to the protocol are necessary. Do not take any further steps without speaking to a medical professional.
