Ovarian hyperstimulation syndrome

[2] Using a GnRH agonist instead of hCG for inducing final oocyte maturation and/or release results in an elimination of the risk of ovarian hyperstimulation syndrome, but a slight decrease of the delivery rate of approximately 6%.

[citation needed] As hCG causes the ovary to undergo extensive luteinization, large amounts of estrogens, progesterone, and local cytokines are released.

Thus, while the woman accumulates fluid in the third space, primarily in the form of ascites, she actually becomes hypovolemic and is at risk for respiratory, circulatory (such as arterial thromboembolism since blood is now thicker), and renal problems.

While this has been repeatedly shown to "virtually eliminate" OHSS risk, there is some controversy regarding the effect on pregnancy rates if a fresh non-donor embryo transfer is attempted, almost certainly due to a luteal phase defect.

[4] In severe forms of OHSS there may be hemoconcentration, thrombosis, distension, oliguria (decreased urine production), pleural effusion, and respiratory distress.

[4] Vaginal ultrasonography in the sagittal plane in a woman with mild OHSS, showing a 33 mm wide anechogenic area behind the uterus in the recto-uterine pouch, which means there was ascites, that is, free fluid in the peritoneal cavity.

[7] A systematic review and meta-analysis concluded that prophylactic treatment with cabergoline reduces the incidence, but not the severity of OHSS, without compromising pregnancy outcomes.

Mild OHSS can be treated conservatively with monitoring of abdominal girth, weight, and discomfort on an outpatient basis until either conception or menstruation occurs.

[citation needed] Moderate OHSS is treated with bed rest, fluids, and close monitoring of labs such as electrolytes and blood counts.

If the OHSS develops within an IVF protocol, it can be prudent to postpone transfer of the pre-embryos since establishment of pregnancy can lengthen the recovery time or contribute to a more severe course.

Over time, if carefully monitored, the condition will naturally reverse to normal – so treatment is typically supportive, although a woman may need to be treated or hospitalized for pain, paracentesis, and/or intravenous hydration.