Ovarian hyperstimulation syndrome (OHSS) occurs when ovaries primed with follicle-stimulating hormone/leuteinizing hormone (LH) are subsequently exposed to human chorionic gonadotropin (hCG). The ultimate pathophysiological step underlying this clinical picture is increased vascular permeability (VP). With the administration of hCG, the expression vascular endothelial growth factor (VEGF) and VEGF receptor 2 (VEGFR-2) mRNA increases significantly rising to a maximum coinciding with peaked VP. Immunohistochemistry shows the presence of VEGF and VEGFR-2 proteins in the granulosa-lutein and endothelial cells of the entire corpus luteum. These findings suggest that the syndrome can be prevented by inducing ovulation with LH or gonadotropin-releasing hormone analogs, which prevent VEGF overexpression. Also, coadministration of a dopamine agonist inhibits phosphorylation of the receptor VEGFR-2. In a trial of 69 oocyte donors, the incidence of moderate OHSS was 20% with the dopamine agonist cabergoline and 44% with a placebo ( P = 0.04). Another dopamine agonist, quinagolide, was also effective in nonpregnant patients, but those pregnant did not benefit from dopamine agonist administration. In conclusion, the pathophysiological mechanisms involved in OHSS show that targeting VEGF/VEGFR2 is an effective preventive approach to treat the syndrome. Pharmaco-prevention through dopamine agonists is effective only in nonpregnant high-risk OHSS women. Embryo cryopreservation plus dopamine agonist administration might be the most appropriate way to prevent OHSS in high-risk patients.

The use of gonadotrophin-releasing hormone (GnRH) agonists for triggering ovulation remains controversial. The primary objective of this study was to evaluate the incidence of ovarian hyperstimulation syndrome (OHSS) following GnRH agonist versus recombinant human chorionic gonadotrophin (HCG) as methods for triggering ovulation. A second aim was to compare the clinical outcome and embryo quality according to the two procedures. The cycle characteristics of 100 oocyte donors undergoing ovarian stimulation and IVF outcomes of their 100 oocyte recipients were analysed. Donors were prospectively randomized into two groups on the last day of ovarian stimulation: Group I received a single bolus of 0.2 mg of triptorelin and Group II received 250 microg of recombinant HCG. No differences were observed in the number of oocytes retrieved or in the proportion of metaphase II oocytes between the groups. The OHSS rate was higher in donors that received recombinant HCG ( P = 0.003). Moreover, there was no significant difference between IVF parameters and outcome in the two groups. In conclusion, a GnRH agonist effectively triggers the final oocyte maturation in oocyte donors without negatively affecting implantation, pregnancy or miscarriage rates. Moreover, this regime effectively eliminates the risk of OHSS in this group of women.

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BACKGROUNDOvarian hyperstimulation syndrome (OHSS) seems to be induced by the ovarian release of vascular endothelial growth factor (VEGF), which increases vascular permeability. Dopamine agonists inhibit VEGF receptor phosphorylation and thereby decrease vascular permeability.METHODSA randomized, double-blind, placebo-controlled, multicentre study assessing three oral doses (50, 100, 200 µg/day) of the non-ergot derived dopamine agonist quinagolide started on the day of human chorionic gonadotrophin (hCG) and continued for 17–21 days without dose-titration in comparison to placebo in preventing moderate/severe early OHSS (onset ≤9 days after hCG administration) in 182 IVF patients with ≥20 but less than 30 follicles ≥10 mm.RESULTSThe incidence of moderate/severe early OHSS was 23% (12/53) in the placebo group and 12% (6/51), 13% (7/52) and 4% (1/26) in the quinagolide 50, 100 and 200 µg/day groups, respectively. The moderate/severe early OHSS rate was significantly lower with all quinagolide groups combined compared with placebo [P = 0.019; OR = 0.28 (0.09–0.81)]. The incidence of ultrasound evidence of ascites among patients with no clinical pregnancy was significantly reduced from 31% (8/26) with placebo to 11% (8/70) with all quinagolide groups combined [P = 0.033; OR = 0.29 (0.10–0.88)], although there was no difference for those with clinical pregnancy. Quinagolide did not have a detrimental effect on pregnancy or live birth rates. The incidence of gastrointestinal and central nervous system adverse events increased with increasing doses of quinagolide.CONCLUSIONSQuinagolide appears to prevent moderate/severe early OHSS while not affecting treatment outcome. The effect is more marked in patients who did not achieve a clinical pregnancy. Quinagolide administered in high doses without dose-titration is associated with poor tolerability.ClinicalTrials.gov Identifier: NCT00329693.

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