OHSS: Ovarian Hyperstimulation Syndrome Explained
OHSS (ovarian hyperstimulation syndrome) is a condition in which the ovaries respond more strongly than expected to the medications used during IVF. Most cases are mild, but it needs monitoring and preventive care.
With modern protocols, the risk of OHSS has been greatly reduced through individualised dosing and close follow-up. Below is an informational overview of its causes, symptoms and prevention.
Why does OHSS happen?
The hormone medications used for ovarian stimulation help several follicles grow. In some women the ovaries over-respond, releasing substances that allow fluid to shift from the blood vessels into the abdomen.
This can become more noticeable after the trigger injection (hCG) or when a pregnancy develops.
Who is at higher risk?
Risk is not the same for everyone. It can be higher in these situations:
- Women with polycystic ovary syndrome (PCOS)
- A high ovarian reserve (high AMH)
- Younger age and lower body weight
- A history of over-response in previous cycles
What are the symptoms?
Mild OHSS may cause bloating, mild discomfort and nausea. Moderate to severe forms can cause weight gain, marked abdominal swelling, vomiting and reduced urine output.
Shortness of breath, severe pain or rapid weight gain are reasons to contact your doctor without delay.
How is it prevented?
Prevention is based on individual planning and close monitoring. Your doctor decides which approach fits you:
- A starting dose tailored to you
- Frequent monitoring with ultrasound and blood tests
- Antagonist protocols and an alternative trigger (agonist trigger)
- Freezing all embryos and postponing transfer when needed (freeze-all)
Treatment and course
Mild cases usually settle on their own with plenty of fluids, rest and follow-up. Moderate to severe cases need medical supervision, sometimes in a hospital setting.
OHSS is most often temporary and, when recognised early, is managed safely.
Related Reading
- IVF Injections and Medications: The Process, Side Effects and Common Questions
- The Stages of IVF Treatment
- IVF Nutrition and Lifestyle: Before, During and After Transfer
Sources and references
This article is supported by the following independent, authoritative sources: