OHSS warning signs, and when to call your clinic
Ovarian hyperstimulation syndrome (OHSS) is when the ovaries overreact to fertility injections and fluid shifts out of the blood vessels into the abdomen. Mild OHSS, with bloating and mild discomfort, is common and settles on its own. Moderate to severe OHSS is uncommon, affecting about 1 in 100 cycles, but needs urgent care. Call your clinic the same day if you have rapidly worsening belly swelling, severe pain, vomiting that stops you keeping fluids down, breathlessness, or you are passing very little urine. This page explains what is normal, what is not, and how clinics prevent it.
Ovarian hyperstimulation syndrome, or OHSS, is a reaction to the injections used to grow multiple eggs. The ovaries become enlarged and, in more serious cases, fluid leaks out of the blood vessels and collects in the abdomen. It is the main safety risk to be aware of during the injection and post-trigger part of an IVF cycle.
Most OHSS is mild and settles by itself. The reason it still deserves a whole page is that the uncommon moderate and severe forms come on over a day or two and need prompt medical care, so it helps to know in advance which signs to act on.
What is normal, and what is not
Some bloating and tenderness after your egg retrieval is expected. Your ovaries have grown many follicles, so the lower belly often feels full and a little sore for several days. The question is not whether you feel bloated, but whether things are staying steady or getting worse.
| Usually mild | Call your clinic | |
|---|---|---|
| Belly | Mild bloating, slowly easing | Swelling that grows visibly day by day, waistband suddenly tight |
| Pain | Mild discomfort, helped by paracetamol | Severe pain, or pain that keeps worsening |
| Stomach | Slight nausea | Vomiting, unable to keep fluids down |
| Breathing | Normal | Breathless, or tight in the chest |
| Urine | Passing urine normally | Passing little urine, or very dark urine |
| Weight | Stable | Rapid gain, more than about 1 kg in a day |
A useful home check is to weigh yourself at the same time each day and note how much urine you are passing. A fast jump in weight or a clear drop in urine means fluid is shifting into your abdomen, and that is the point to phone the clinic rather than wait.
Why it happens, and when
OHSS is driven by hCG. That is why it tends to appear in two windows: a few days after the trigger shot (which contains hCG), and again later if an embryo implants and the body starts making its own hCG. This second window is why a positive pregnancy can sometimes come with worsening symptoms, and why clinics watch high-risk patients into the two-week wait.
Higher risk comes with a strong response to stimulation: many follicles, a high AMH or high antral follicle count, younger age, or polycystic ovaries (PCOS).
How clinics prevent it
Good clinics plan around this risk rather than react to it. Common measures, supported by fertility-society guidelines, include:
- Using an antagonist protocol, which allows a safer trigger option in high responders.
- Replacing the hCG trigger with a GnRH-agonist (a 'lupride' or agonist trigger) when the response is strong.
- Adjusting or lowering the injection dose during the cycle based on scan and blood monitoring.
- Choosing a 'freeze-all' cycle: freezing all embryos and transferring later, which avoids the pregnancy-driven second wave of OHSS.
- Prescribing cabergoline tablets after the trigger to reduce fluid leakage in at-risk patients.
If your clinic recommends freezing all embryos instead of a fresh transfer, this is often a safety decision, not a setback. It lets the ovaries settle and, in high responders, gives a similar or better chance in a later frozen cycle.
A note for India
Fertility injections are managed on an outpatient basis here, so most monitoring and the trigger decision happen at day visits, and you carry the responsibility of spotting worsening symptoms at home between them. Keep your clinic's number and your treating doctor's name saved and reachable, including who to call after hours. If symptoms turn severe at night or while travelling and you cannot reach the clinic, go to the nearest hospital with an emergency department and say clearly that you are in an IVF cycle and may have OHSS, because a general casualty doctor may not assume it.
- Mild OHSS is common, affecting up to a third of cycles. Moderate to severe OHSS, the kind needing medical care, is uncommon, at roughly 1 in 100 cycles, and clinics actively work to prevent it in higher-risk patients.
- Some bloating and tenderness is normal after retrieval. The warning sign is worsening: swelling that grows day by day, severe pain, vomiting, breathlessness, or passing little urine. Steady mild bloating that slowly eases is usually fine, but call your clinic if you are unsure.
- Yes. If a pregnancy starts, the body's own hCG can trigger a later wave of OHSS in high responders. This is one reason clinics sometimes freeze all embryos and transfer in a later cycle instead of doing a fresh transfer.
- Staying hydrated with fluids, and salty drinks or oral rehydration solution, is generally advised in mild OHSS, but it is not a substitute for medical review if symptoms are worsening. Follow your clinic's specific advice.
How common is serious OHSS?
I am bloated after egg retrieval. Should I worry?
Can OHSS happen after the embryo transfer?
Does drinking more water help?
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