OVARIAN HYPER STIMULATION SYNDROME (OHSS) is a serious consequence caused when ovulation is induced in assisted reproductive treatment. It is extremely dangerous especially in Polycystic ovarian syndrome (PCOS). More than 20-25 total amount of follicles present during use of medication to stimulate follicle growth, will categorize the woman as being at high risk.
OHSS develops after stimulation of the ovaries with medication such as human chorionic gonadotrophin (hCG) and human menopausal gonadotrophin. It rarely happens when ovarian induction is with mild stimulation such as Clomiphene. However care must be given in all cases when PCOS has been diagnosed.
Figure 1: Shows a Polycystic ovary. [1]
Women at risk:
- PCOS
- Young women.
- High Oestrogen Levels.
- Large number of antral follicles.
- Progesterone medication for luteal support.
Symptoms: These usually manifest themselves on the 4-5 day post Egg Collection. Women complain of severe abdominal bloating, nausea, vomiting, reduced and concentrated urine and excessive and unexplained weight gain. In severe cases these can be accompanied with breathlessness due to hydrothorax; fluid passing from the abdominal cavity to the pleural cavity. Figure: 2a [1] This extravasation of excess fluid will result in haemoconcentration and hypercoagulability, increasing the risk of thrombosis, reduced renal function and if left untreated can lead to ovarian torsion or even renal failure. OHSS is classified as mild, moderate, severe and critical depending on the severity of symptoms.[2] Figure: 2b
Figure: 2a Shows sites of hydrothorax and abdominal ascites.
Classification:
| Grade and associated clinical features[1] | |
|---|---|
| Mild OHSS |
|
| Moderate OHSS |
|
| Severe OHSS |
|
| Critical OHSS |
|
Figure: 2b Shows Classifications of OHSS
Diagnostic investigations:
- High Oestrogen levels indicate follicle over stimulation.
- High Full Blood count indicating haemoconcentration.
- Abnormal Coagulation screens; risk of thrombosis.
- Chest X-Ray to exclude hydrothorax.
- Daily measurement of abdominal girth and weight.
- Liver function test.
- Urea and Electrolytes for renal function.
Management:
If OHSS is suspected, Egg Collection can be performed, but fresh Embryo transfer has to be postponed. The embryos are cryopreserved for a later date. A woman may take months to recover from severe OHSS. A pregnancy would put the woman at a higher risk of developing severe OHSS especially in multiple pregnancies. Women are encouraged to keep well hydrated during stimulation of ovaries. If symptoms persist or worsen, then the best course of action is for patient to be admitted into hospital for observations. Intake and output of fluids are carefully monitored. In severe cases, aspiration of ascites ( abdominal fluid) or pleural effusion may be performed to relief symptoms. Albumin infusion is usually administered to replace circulatory volume. Women suspected of having PCOS are carefully monitored prior assisted reproductive treatment is started.
Course of action may be:
- Laparoscopic Ovarian Drilling to remove excessive large follicles. Figure: 3
- Metformin medication. This is prescribed to women with PCO to treat poor insulin response.
- ‘Coasting’. Follicle stimulation is withheld to control Oestrogen levels.
Figure: 3 Showing Laparascopic Approach for Ovarian Drilling.[1]Ovarian Drilling by Laparoscopy for PCOS – YouTube
Bibliography:
1. Figures: 1, 2,3 and 4 https://www.google.co.uk/search
2. http://www.patient.co.uk/doctor/Ovarian-Hyperstimulation-Syndrome.htm
3. www.youtube.com/watch?v=JH-Yx1QWUBk
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