Ovarian hyperstimulation.
When does OHSS occur?
In most cases, ovarian hyperstimulation follows a process of controlled stimulation of the ovaries with pituitary gonadotropin drugs, which precedes IVF or other assisted reproductive techniques. However, the disorder can also occur in the course of a natural pregnancy - doctors suspect that it occurs due to a mutation of the FSH hormone receptor, increasing its sensitivity to the hCG hormone secreted during pregnancy.
Ovarian stimulation in the treatment of infertility
What is ovarian hormonal stimulation and why is it carried out? Most commonly, it is part of fertility support therapy. Hormone stimulation of the ovaries involves administering drugs to the woman to stimulate the ovarian follicles to grow and then the hormone hCG, which induces ovulation and plays an important role in oocyte maturation. Performing artificial stimulation in preparation for IVF increases the patient's chances of obtaining a sufficiently high number of mature oocytes, which can then be fertilised under laboratory conditions.
Too few oocytes are an obstacle to continuing with the procedure. Hormone stimulation is therefore used for most women undergoing IVF. Unfortunately, it is not without effect on the body and can lead to ovarian hyperstimulation syndrome, which statistics show is the second most common complication (after multiple pregnancies) when trying to have a baby using assisted reproduction techniques.
Symptoms of ovarian hyperstimulation syndrome OHSS
Ovarian hyperstimulation can have one of four forms: mild, moderate, severe or critical.
- The mild form of ovarian hyperstimulation syndrome manifests as abdominal swelling, nausea and flatulence. In most women, these symptoms resolve spontaneously after a few days (a visible improvement usually occurs after menstruation), as the dose of hCG hormone given at the end of stimulation only persists in the bloodstream for 6-9 days.
- Moderately severe hyperstimulation syndrome, in addition to the complaints typical of the mild form, manifests itself with diarrhoea or vomiting, abdominal pain and enlargement of the abdominal circumference.
- In the severe and critical form, ovarian hyperstimulation causes respiratory distress, massive ascites and very marked enlargement of the ovaries. Without the implementation of appropriate treatment, it can result in coagulation disorders, circulatory failure or even death of the patient.
Who is particularly vulnerable to ovarian hyperstimulation?
Not every woman is at risk of developing ovarian hyperstimulation to the same degree. Women who are slim, younger, have a high ovarian reserve and have been diagnosed with polycystic ovarian syndrome are more likely to develop the disorder. The number of ovarian follicles stimulated and the concentration of sex hormones also play an important role in the development of the disorder (AMH concentration before stimulation and an increase in oestradiol during stimulation), so these parameters are closely monitored during treatment.
Ovarian hyperstimulation - treatment
A patient diagnosed with ovarian hyperstimulation syndrome should be under constant medical care, especially for the more severe forms of the disorder.
The mainstay of hospital treatment is the ongoing replenishment of electrolytes, albumin and protein, and an adequate supply of intravenous fluids. The woman's circulatory and respiratory capacity, urine output and all major laboratory parameters should be monitored. To prevent thromboembolic complications, the patient is given heparin preparations. If there is an accumulation of fluid in the pleura or abdominal cavity, it is necessary to decompress it, i.e. to puncture the abdominal cavity or pleura and drain the excess fluid. Sometimes there is a need to implement dialysis therapy.
During the treatment of mild to moderate ovarian hyperstimulation syndrome, a protein-rich diet and isotonic fluid intake are indicated. Due to the increased risk of thromboembolism, physical activity should be maintained and prolonged sitting or lying in bed should be avoided.
Prevention of ovarian hyperstimulation
The likelihood of ovarian hyperstimulation syndrome decreases when the stimulation protocol and safe dose of hormonal drugs are properly selected - this is achieved through detailed diagnostic testing before treatment and identification of risk factors. In addition, monitoring of sex hormone levels is used to detect possible abnormalities as early as possible.
If, at the IVF preparation stage, the doctor identifies the presence of a number of risk factors and thus an increased susceptibility to the development of hyperstimulation syndrome, he or she may recommend that the patient use a different preparation that does not contain the hCG hormone. This is why it is extremely important to have ovarian stimulation carried out by an experienced and specialised doctor in an infertility clinic.
Ovarian hyperstimulation and embryo transfer
The first symptoms of ovarian hyperstimulation syndrome may appear within three to seven days of the hCG dose, in which case we are dealing with an early-onset condition that is dependent on the drugs used during infertility treatment. If the onset of hyperstimulation symptoms has occurred after ten days or more, this is the so-called late-onset form of hyperstimulation, stimulated by natural hormones secreted early in pregnancy. As statistics show, late-onset disease accounts for as many as 70% severe cases of ovarian hyperstimulation.
To prevent the two forms of the disease from overlapping, the doctor may decide to postpone the embryo transfer until the next cycle. The most important thing here is the safety of the patient. This is why it is so important to remain under the constant supervision of an experienced doctor in an infertility clinic. At InviMed clinics, all patients are treated individually. The treatment takes place under the watchful eye of the doctor - so as to avoid any problems and react quickly to any emerging risks.
Ovarian hyperstimulation and pregnancy
When a woman with a mild form of ovarian hyperstimulation syndrome becomes pregnant, the risk of an exacerbation of the condition must be taken into account. Fortunately, this is rare and the severity of the symptoms is not dramatic - usually the mild form progresses to moderate and treatment is limited to rest and intake of large amounts of fluids (preferably so-called isotonic). Hospital treatment is only implemented when additional symptoms occur, such as:
- increase in abdominal circumference,
- excessive weight gain,
- a reduction in the amount of urine excreted.
Ovarian hyperstimulation - complications and risks
Women affected by ovarian hyperstimulation syndrome may develop deep vein thrombosis or pulmonary embolism as a result of excessive blood density. Hyperstimulation in pregnant patients increases the risk of cholestasis, gestational diabetes, intrauterine infection, miscarriage or preterm delivery. Cholestasis does not affect the foetus and possible complications in children are, according to doctors, related to pregnancy complications. During the assisted reproduction procedure, it is important to remain under the care of an experienced doctor. Regular visits to a specialist and examinations are able to quickly diagnose possible abnormalities and prevent their consequences.
Medical consultation of the article:
Dr Robert Gizler with InviMed Wrocław and Lukasz Lewandowski, MD from InviMed Poznan.
Read also:
Polycystic ovary syndrome (PCOS) - does it make it harder to get pregnant?
How long do egg cells live? Find out how you can take care of them