Donor Risks and Complications

Ovarian Hyperstimulation Syndrome [OHSS]

The medications (gonadotropins) used to stimulate your ovaries during in-vitro fertilization (IVF) or associated procedures for fertility treatment are designed to ensure that a reasonable number of eggs are obtained to maximize your chances of pregnancy.

Ovarian Hyperstimulation Syndrome (OHSS) happens when too many ovarian follicles have developed in response to the usual dosage of medication. It is a result of the hormones produced by the ovaries in response to the drugs given. OHSS is usually mild and causes no more than a slight lower abdominal discomfort in most cases. Although uncommon, it warrants medical attention as it can be potentially life threatening if left untreated in severe cases. When detected early and managed appropriately, the condition can be alleviated.

Occurrence of OHSS

Some 6 to 8 percent of patients undergoing IVF treatment will experience mild forms of OHSS. The severe form will affect less than one percent of patients.


You may be developing OHSS if you experience some or all of the following symptoms :

  • Persistent lower abdominal discomfort
  • Nausea and vomiting
  • Bloatedness or swelling of the abdomen and genital area
  • Shortness of breath
  • Dehydration
  • Reduction of urine volume
  • Abdominal pain

Medical Attention

OHSS is usually self-limiting and can then be treated at home with rest and adequate fluid intake. Immediate medical attention is required should the symptoms persist or worsen. In this instance, admission to hospital for treatment and close monitoring are required. Most of the time, the symptoms will subside in 5 to 10 days.


Prevention is the best form of treatment and we will endeavor to avoid OHSS at all stages. Some women are more likely to develop OHSS, especially those with polycystic ovaries, those who are thin and those who had responded with many follicles or experienced OHSS in the past. We may recommend abandoning the cycle before the hCG injection if your risks of OHSS are high or unexpected rigorous response is encountered in your cycle.

If you are undergoing the IVF/ICSI, your eggs may be collected but you may not have fresh embryo transfer. The resulting good quality embryos will be frozen for later use.

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