What is OHSS?
Ovarian hyperstimulation syndrome is the body’s response to excess hormones, causing the ovaries to swell and become painful. Women who are using fertility medication during IVF to stimulate egg growth are at risk of developing the condition. Typically, high levels of human chorionic gonadotropin (hCG) create unwanted side effects that can range from mild to severe.
Pain, bloating, and nausea
Approximately 3-6% of women who undergo IVF will experience OHSS. Symptoms can include abdominal pain, nausea, vomiting, tenderness in the ovaries, bloating, and diarrhea. In severe cases, women can experience persistent nausea, shortness of breath, a tight or enlarged abdomen, severe pain, and blood clots. If OHSS is suspected, a doctor should be consulted immediately. To avoid the risk of OHSS, women can consider frozen embryo transfer, an approach offering multiple benefits.
1. No hormone stimulation
During IVF, the patient is given fertility medication to promote egg growth before a retrieval is scheduled. Once retrieved, the eggs are combined with sperm in the lab to create an embryo. In some cases, the embryo can be transferred into the uterus during the same cycle. However, for women who want to decrease the risk of OHSS, a frozen embryo transfer may be preferred. In this scenario, the retrieval and transfer are separated by at least 1 cycle with the eggs frozen in between. This break gives the body time to recover from the artificial hormones before the transfer occurs. Once ready, the FET cycle can take place without the addition of hCG or other fertility hormones.
2. Less pressure for more eggs
Another benefit of FET is less pressure to produce multiple eggs in a single cycle. Women planning for a fresh transfer will want to do everything possible to make sure enough eggs are retrieved so a viable option can be transferred right after. This can mean aggressive hormone regimens. With FET, patients are afforded the benefit of time and can use lower hormone doses to stimulate egg growth. If a retrieval only produces 1 or 2 eggs, another cycle can be scheduled at a later date. Once the patient has enough embryos frozen, a transfer can be performed.
3. Higher success with FET
In addition to reducing the risk of OHSS, a frozen transfer is thought to have higher odds of pregnancy success. Studies show that women who use frozen embryos have significantly higher rates of clinical pregnancy, ongoing pregnancy, and live birth. Fewer side effects and higher chances of a baby are sure to convince any woman of the benefits of frozen transfer.
FET to avoid OHSS
Although any egg retrieval using fertility medication can cause OHSS, the risk can be lowered with specific approaches. Separating the retrieval and transfer into 2 different cycles can give the body a necessary break and allow hormones to clear from the system. A frozen approach also decreases the pressure to use high doses of hormones to retrieve multiple eggs at once. Lastly, A FET transfer offers the benefit of higher chances of success. Although each case is unique, IVF patients looking to avoid OHSS and successfully become pregnant should consider a frozen embryo transfer when pursuing fertility treatment.