Ovarian hyperstimulation syndrome

This iatrogenic condition results from overstimulation of the ovaries in the course of infertility treatment. It most commonly is associated with gonadotrophin therapy.

Women at risk of ovarian hyperstimulation syndrome (OHSS) are generally young and have polycystic ovary syndrome (PCOS) (1).

• women with a previous history of OHSS, polycystic ovary syndrome, increased antral follicle count (AFC) or high levels of anti-Mullerian hormone (AMH) are at an increased risk of OHSS (2)

OHSS is characterised by enlarged ovaries and an acute fluid shift from the intravascular space to the third space (mainly to the abdominal or thoracic cavity), which may result in an accumulation of fluid in the peritoneal cavity and pleura, an elevation of haematocrit, and a decrease in organ perfusion.

Mild hyperstimulation occurs in up to 10% of patients receiving hMG. Ovarian enlargement and cyst formation produces abdominal discomfort, swelling and pain. Rest and simple analgesia for example, aspirin provides relief.

Moderate or severe OHSS arises in 3% to 8% of IVF cycles (2)

Moderate hyperstimulation is indicated by nausea, vomiting, diarrhoea, abdominal discomfort and often, some weight gain. Treatment is as for mild hyperstimulation but patients should be closely monitored in case symptoms worsen.

Severe hyperstimulation occurs in about 1% of patients. There may be ascites and pleural effusion. Changes in blood clotting may result in thrombosis. Hospitilisation is required with correction of fluid abnormalities.

Prevention requires careful monitoring - ultrasound to assess the number and size of the follicles, and testing of serum oestrogen levels.

There is evidence that dopamine agonists probably reduce the incidence of moderate or severe OHSS compared to placebo/no intervention (3)

Reference:

• Costello MF et al. Treatment of infertility in polycystic ovary syndrome: a brief update. Australian & New Zealand Journal of Obstetrics & Gynaecology 2012;52(4):400-3.
• Royal College of Obstetricians and Gynaecologists (RCOG). The management of ovarian hyperstimulation syndrome. London (UK): Royal College of bstetricians and Gynaecologists (RCOG). Green-top Guideline No 5 2016
• Tang H, Mourad SM., Wang A, Zhai S-D, Hart RJ. Dopamine agonists for preventing ovarian hyperstimulation syndrome. Cochrane Database of Systematic Reviews 2021, Issue 4. Art. No.CD008605. DOI: 10.1002/14651858.CD008605.pub4. Accessed 01 September 2021.