Ovarian hyperstimulation syndrome (OHSS) is a potential complication of in vitro fertilisation (IVF) treatment. It occurs when the ovaries respond excessively to fertility medications used to stimulate egg development. Recognising OHSS symptoms after IVF is important because the condition can range from mild abdominal discomfort to serious complications that require urgent medical attention.

In India, individuals undergoing fertility treatment may experience bloating, pelvic discomfort, or nausea following egg retrieval. Although some discomfort can be expected after the procedure, worsening symptoms should not be ignored. Understanding the common signs, their timing, and the difference between mild and severe OHSS can help individuals recognise when medical assessment is necessary.

What Is OHSS After IVF?

OHSS develops when the ovaries react excessively to the hormonal medications used during ovarian stimulation. The ovaries may become enlarged, and fluid can move from blood vessels into surrounding tissues and the abdominal cavity.

This fluid accumulation can cause abdominal swelling, discomfort, nausea, and weight gain. In severe cases, OHSS may affect kidney function, breathing, and blood circulation, increasing the risk of blood clots.

Not everyone undergoing IVF develops OHSS. The severity varies depending on the individual's response to fertility medications and other medical factors. Most cases are mild, while severe cases require closer monitoring and sometimes hospital treatment. Source: Royal College of Obstetricians and Gynaecologists

What Are the Common OHSS Symptoms After IVF?

Symptoms may develop after the egg retrieval procedure or following embryo transfer, depending on the treatment cycle and hormonal changes.

Common symptoms include:

• Abdominal bloating: The abdomen may feel unusually full, swollen, or tight.
• Abdominal or pelvic pain: Discomfort may range from mild pressure to increasing pain.
• Nausea and vomiting: Hormonal changes and fluid accumulation can cause digestive discomfort.
• Rapid weight gain: A sudden increase in weight may indicate fluid retention rather than ordinary weight changes.
• Reduced appetite: Abdominal fullness and nausea may make eating uncomfortable.
• Diarrhoea: Some individuals experience changes in bowel movements.
• Increased thirst: Excessive thirst may indicate dehydration or fluid imbalance.
• Reduced urination: Passing less urine than usual, particularly dark or concentrated urine, may indicate a more serious problem.

These symptoms do not automatically confirm OHSS. However, symptoms that persist, worsen, or occur together after IVF require medical assessment.

When Do OHSS Symptoms Start After IVF?

The timing of OHSS varies according to the type of fertility treatment and whether pregnancy occurs.

Early-onset OHSS generally develops within the first several days after the ovulation-trigger injection or egg retrieval. It is commonly associated with the body's response to fertility medications.

Late-onset OHSS may develop around nine days or more after the trigger injection and is often associated with pregnancy-related hormonal changes. When pregnancy occurs, symptoms may become more severe or last longer.

Mild symptoms may improve over approximately seven to ten days. However, if pregnancy occurs, OHSS can persist for several weeks.

The timing alone cannot establish whether symptoms are harmless or serious. A healthcare professional should evaluate concerning changes, particularly when abdominal swelling or pain is increasing.

Mild, Moderate, and Severe OHSS Symptoms

OHSS is generally classified according to symptom severity and clinical findings.

Mild OHSS

Mild OHSS may involve slight abdominal bloating, pelvic discomfort, mild nausea, and enlarged ovaries. Symptoms are often manageable with appropriate medical guidance and monitoring.

However, even mild symptoms should be reported to the treating fertility team because the condition can sometimes progress.

Moderate OHSS

Moderate OHSS may involve more noticeable abdominal swelling, increasing discomfort, nausea, vomiting, and fluid accumulation within the abdominal cavity.

Individuals may notice that their clothes feel tighter around the waist or that their weight is increasing over a short period. Medical assessment is important to determine whether additional monitoring or treatment is required.

Severe OHSS

Severe OHSS can affect essential body functions and requires urgent medical evaluation. Warning signs include:

• Severe or persistent abdominal pain.
• Significant abdominal swelling or rapid weight gain.
• Repeated vomiting or inability to retain fluids.
• Very little urine or dark, concentrated urine.
• Extreme thirst or signs of dehydration.
• Difficulty breathing or chest pain.
• Painful swelling or tenderness in one leg.

Difficulty breathing, chest pain, fainting, or markedly reduced urine output should be treated as emergency warning signs. Immediate assessment at the nearest emergency department may be necessary. Source: NHS

Who Has a Higher Risk of OHSS After IVF?

Certain factors can increase the likelihood of developing OHSS. These include polycystic ovary syndrome (PCOS), a previous episode of OHSS, younger age, elevated anti-Müllerian hormone levels, and a high number of developing ovarian follicles.

The type and dose of fertility medication and the body's response to ovarian stimulation also influence risk. Pregnancy during the same treatment cycle can increase the severity or duration of OHSS in some individuals.

However, OHSS can occasionally occur even when risk factors are not obvious. Individual risk assessment and monitoring are therefore important throughout IVF treatment.

How Is OHSS Diagnosed and Managed?

A healthcare professional may review symptoms, recent fertility medications, weight changes, and urine output. Depending on the findings, investigations may include blood tests, ultrasound examinations, and assessments of kidney function and fluid accumulation.

Management depends on severity. Mild cases may be monitored outside the hospital with guidance about fluid intake, activity, and symptom tracking. Moderate or severe cases may require closer observation, intravenous fluids, medication, or hospital admission.

Individuals should not independently change prescribed fertility medications or begin medicines for pain or fluid management without medical advice.

Conclusion

OHSS symptoms after IVF can range from mild bloating and abdominal discomfort to serious problems involving dehydration, kidney function, breathing, or blood clots. Recognising worsening symptoms and seeking timely medical advice are essential for preventing complications.

Although most cases are mild, persistent pain, repeated vomiting, reduced urination, rapid weight gain, chest pain, or breathing difficulties should never be dismissed as routine effects of IVF. Awareness of the symptoms, their timing, and their potential severity helps individuals make informed decisions about seeking appropriate medical care.