OHSS After IVF: Symptoms, Prevention and When to See a Doctor

Dr. Anshika Lekhi, MBBS, MS (Obstetrics & Gynecology), The Fertilife, Gurgaon

Ovarian hyperstimulation syndrome is the complication of IVF that patients hear about and rarely have explained properly. Mild forms are common enough to be expected. The severe form is uncommon and is a medical emergency, and the distinction between those two sentences is what this page is for.

Call Someone If

Before anything else, because this is the part that matters most.

Contact your clinic the same day if you have rapidly worsening abdominal swelling, significant weight gain over a day or two, severe abdominal pain, persistent vomiting, breathlessness or difficulty lying flat, noticeably reduced urine output, or calf pain and swelling.

Do not wait for your next scheduled appointment, and do not wait for morning.

What OHSS Actually Is

The mechanism

Stimulation drugs recruit many follicles rather than the single one a natural cycle produces. In some women the ovaries overrespond, and after the trigger injection they release substances that make blood vessels leak fluid into the abdomen.

That fluid shift is the problem. It causes the swelling, and in severe cases it thickens the blood and strains the circulation.

Mild, moderate, severe

Mild means bloating, mild abdominal discomfort and slight nausea, and it settles on its own. Moderate adds more marked swelling, vomiting and weight gain, and needs monitoring. Severe involves significant fluid accumulation, breathing difficulty and the circulatory effects, and needs hospital care.

Most women who get any OHSS get the mild form.

Who Is More at Risk

The main risk factors

Younger women, those with a high antral follicle count or high AMH, and women with polycystic ovaries are all at higher risk, because those ovaries respond vigorously to stimulation.

If it has happened before

A previous episode of OHSS raises your risk in subsequent cycles. If you have PCOS, this should be an explicit part of your protocol discussion before stimulation starts, not something raised afterwards.

How It Is Prevented

The protocol does most of the work

Prevention is largely about how the cycle is designed, and modern practice has reduced severe OHSS considerably. Current reviews of stimulation strategy set out the approaches: antagonist protocols, individualised starting doses based on reserve testing rather than a standard dose, and careful monitoring so the dose can be reduced if the response runs ahead.

The trigger and the freeze-all

Two decisions matter most. An alternative trigger can be used in place of hCG in women responding strongly, because hCG is what drives the fluid leak and it persists in the body.

And a freeze-all cycle removes the other driver. If no embryo is transferred and no pregnancy follows immediately, the hormone surge that worsens OHSS does not happen, so everything is vitrified and transferred in a later prepared cycle.

Both of these cost you a few weeks and are worth it.

If You Develop It

Mild cases

Mild cases are managed at home with rest, adequate fluids, paracetamol for discomfort and daily weight checks so any change is caught. Your clinic will want to hear from you rather than wait.

More serious cases

Moderate and severe cases need review, sometimes scans and bloods, and occasionally admission for fluids or drainage of accumulated fluid. The NHS summary of IVF risks covers where this sits among the other complications.

How long it lasts

Symptoms typically settle over a week to ten days if pregnancy has not occurred. If it has, the course can be longer, because the pregnancy itself produces hCG.

Why Timing of Symptoms Matters

There are two patterns and they behave differently.

Early OHSS appears within about a week of the trigger and is driven by the trigger injection itself. It tends to settle as that hormone clears.

Late OHSS appears later and is driven by the pregnancy hormone from an implanting embryo. It can be more persistent, precisely because the source keeps producing, and it is the pattern that most often needs closer management.

Telling your clinic exactly when symptoms started is genuinely useful information, so note the date rather than describing it vaguely.

What to Ask Before Your Cycle

Ask what my AMH and follicle count suggest about my risk. Ask which protocol is planned and why. Ask what trigger will be used and whether an alternative is appropriate for me. Ask whether a freeze-all is being considered.

Then ask for the out-of-hours number, and keep it somewhere you will find it at two in the morning. Our patient journey sets out each stage of an IVF cycle, and you can reach us on +91 73037 08364.

This page is educational and does not replace medical advice. If you develop symptoms of OHSS, contact your fertility clinic straight away or seek urgent care.