What Is Ovarian Hyperstimulation Syndrome? Can It Be Prevented?

Ovarian hyperstimulation syndrome (OHSS) is a disease of women receiving follicle stimulating hormone (FSH) to have mature egg cells during the IVF process. During the IVF procedures, some patients may develop reactions to the medications they receive. If more than a few egg cells develop during these procedures, the ovaries will be enlarged in size and side effects may occur within 15 days because of the high levels of hormones secreted from these ovaries. The constellation of these side effects are called ovarian hyperstimulation syndrome (OHSS). OHSS is usually encountered in female patients undergoing IVF because this procedure requires stimulation of the ovaries with medication to increase the number of mature egg cells. This syndrome can be seen in women undergoing ovulation induction and artificial insemination after obtaining the mature egg cells. But hyperstimulation syndrome is usually seen in women undergoing in vitro fertilization (IVF).

All patients receiving IVF-associated medication experience minor symptoms of OHSS. The majority of symptoms in most patients can be controlled sufficiently enough not to interfere with the daily life.

How Does Hyperstimulation Occur? 

The exact underlying mechanisms causing hyperstimulation syndrome in women with extremely low or high egg counts have not been established yet. However, a considerable number of eggs should be formed in order to see a full-fledged syndrome. The higher the number of maturing eggs, the greater will be the risk to develop the syndrome. In the female body, ovarian hormones and other hormones secreted in the body affect the permeability of small blood cells. For this reason, some fluid accumulation may occur at spaces, where it should not be. The abberrant accumulation of fluid causes bloating and discomfort. At the same time, the fluid accumulation will reduce the volume of fluid drained in the kidneys, consequently leading to a lower urine output and disordered sodium - potassium balance. What are the  OHSS symptoms? OHHS symptoms include the following: Pain in the lower abdomen due to enlarged ovaries; nausea, vomiting, diarrhea and rapid weight gain; in severe disease, shortness of breath due to fluid collection in the lungs and a predisposition to thrombosis; changes in the fluid and electrolyte balance, and dehydration meaning that the body cannot get enough water.  What are the severity categories of the ovarian hyperstimulation syndrome? OHSS is categorized as mild, moderate, and severe. Mild and Moderate OHSS: In mild and moderate OHSS,the symptoms include bloating in the abdomen, ovarian enlargement, feeling of discomfort, excessive weight gain, and nausea. These categories of severity account for 10% of OHSS cases. Severe OHSS: In severe OHSS; the abdomen swells more compared to the milder forms of the syndrome; the abdominal pain is severe, and the weight gain is excessive. Patients suffer from shortness of breath, nausea, vomiting; and they have reduced urine volume. The incidence of the severe category is lower than 2%. Patients suffering from a severe form of the syndrome usually require inpatient hospital care so that they can be followed up closely during the treatment. This group of patients is usually encountered when they first achieved conception. Resolution of symptoms may take longer compared to a natural recovery process. What determines the severity of Ovarian Hyperstimulation Syndrome (OHSS)? The severity of OHSS depends directly on the maturing follicle count and  the excess estradiol levels in the serum. If OHHS is severe or moderate and if it has a progressing disease course, inpatient treatment is necessary. Fluid replacement should be definitely performed. Nausea and vomiting should be treated with medications or injections under the supervision of a physician. As a precaution against the risk of thrombosis, heparin injection is recommended. Paracentesis is another treatment method; which is performed by withdrawing the excess fluid in the abdominal cavity. It is one of the most beneficial treatment methods in severe and progressive disease grades. If OHSS does not occur with pregnancy, it will generally disappear gradually within 10 days. If the patient is pregnant, the symptoms will remain to be apparent for 15 or 20 days. If this clinical picture is not severe, the manifestations will resolve spontaneously and will not act on pregnancy negatively.