Background: Ovarian hyperstimulation syndrome (OHSS) is an iatrogenic adverse effect of ovarian stimulation in susceptible women. It is an exaggerated response to ovarian stimulation characterized by the shift of fluid from the intravascular space to the third space, specifically the abdominal cavity. OHSS is associated with physical and psychosocial morbidity and may lead to maternal death.Exposure of the stimulated ovaries to HCG leads to the production of vascular endothelial growth factor (VEGF) which is involved in the initiation of the OHSS. The VEGF-induced vascular permeability leads to loss of fluid into the third space (ascites or, less commonly, pleural, and pericardial effusions). In severe OHSS cases hypovolemia, with a typical loss of 20% of blood volume may occur.
Case presentation: 54 cases, all of them were complaining of primary infertility. All patients were average responders, ICSI was planned for all of them. They were stimulated with gonadotropin in a long agonist protocol and triggered by 5000 HCG followed by ovum pickup under transvaginal sonographic guide then Treatment by letrozole immediately after oocyte retrieval and for 5 days plus agonist continued for 5 days plus LPS FOR.
Conclusion: The concomitant use of Letrozole after OR with agonist may be considered for "switching off" unexpected hyper response, to protect them from OHSS.