Trigger Shots in IVF: Medication Options & OHSS Prevention

What Is a Trigger Shot in IVF?

In the U.S., trigger shots play a crucial role in IVF treatment, helping mature follicles rupture and release eggs for retrieval. Timing the trigger shot correctly is essential for successful egg collection and embryo development. However, different trigger shot medications work in distinct ways, and doctors tailor their choice based on each patient’s specific needs and response to treatment.

At the same time, ovarian hyperstimulation syndrome (OHSS) is a potential risk in IVF. The use of trigger shots can sometimes contribute to this condition, making careful monitoring and prevention strategies necessary.

Types of Trigger Shots in IVF

hCG-Based Trigger Shots

hCG (human chorionic gonadotropin) trigger shots are the most commonly used in IVF. They mimic the body’s natural ovulation process, stimulating the final maturation and release of eggs. The most common hCG-based trigger shots include:

• Ovidrel – A recombinant hCG injection that mimics the luteinizing hormone (LH) surge, triggering ovulation approximately 36 hours after injection.

• Novarel – A urinary-derived hCG medication that works similarly to Ovidrel, promoting follicle rupture for egg retrieval.

• Pregnyl – Another hCG-based trigger shot that supports final follicle maturation and ovulation.

Advantages of hCG Trigger Shots

hCG-based trigger shots are highly effective because they closely resemble the body’s natural ovulation signals. This optimizes egg maturation and increases IVF success rates. However, in some cases, hCG can contribute to OHSS, especially in patients with high ovarian response.

GnRH Agonist Trigger Shots (Lupron)

Unlike hCG, GnRH agonists (such as Lupron) work by first stimulating then suppressing the release of LH and FSH. This allows doctors to precisely control ovulation timing and reduce the risk of OHSS.

GnRH agonist trigger shots are used to:

✔️ Control ovulation timing, ensuring follicles are retrieved at their optimal stage.✔️ Reduce OHSS risk by preventing excessive ovarian stimulation.✔️ Improve treatment safety, especially for high-risk patients.

Although GnRH agonists require longer treatment duration, they provide greater precision in ovulation control.

Preventing Ovarian Hyperstimulation Syndrome (OHSS)

OHSS is a serious complication that can occur during IVF, particularly when using ovulation-inducing medications. Symptoms include ovarian enlargement, abdominal pain, bloating, and fluid retention, which can become severe in some cases.

Because trigger shots play a role in ovarian response, it is crucial to implement preventative strategies to reduce OHSS risk.

Key OHSS Prevention Strategies in IVF

1️⃣ Precise Medication DosingDoctors carefully adjust trigger shot dosage based on ovarian response. For high-responders, lower hCG doses may be used to prevent overstimulation.

2️⃣ Frequent Ovarian MonitoringUltrasounds and hormone level tracking help assess follicle development, allowing doctors to modify treatment plans and prevent excessive stimulation.

3️⃣ GnRH Antagonist UseGnRH antagonists like Cetrotide and Ganirelix can help prevent premature ovulation and reduce the risk of OHSS in high-risk patients.

4️⃣ Low-Dose hCG ProtocolFor patients prone to OHSS, doctors may opt for a low-dose hCG trigger, such as a half-dose of Ovidrel, to minimize stimulation while still ensuring ovulation.

5️⃣ Embryo Freezing StrategyIf signs of OHSS appear, doctors may freeze all embryos and delay transfer. This allows the patient’s body to recover before proceeding with implantation, reducing complications.

Conclusion

In U.S. IVF treatments, trigger shots are essential for egg retrieval, but their correct use is key to success and safety. Different trigger shots, such as hCG-based and GnRH agonists, have distinct mechanisms, and doctors choose the most suitable one based on the patient’s response.

Since OHSS is a significant concern, strategies like dose adjustment, monitoring, GnRH antagonist use, and embryo freezing help prevent complications and enhance treatment outcomes. With personalized care and scientific advancements, IVF success rates continue to improve, offering hopeful parents a safer and more effective fertility journey.

Would you like to explore personalized IVF options? Contact Legend Family today to learn more!

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