Use of a single bolus of GnRH agonist triptorelin to trigger ovulation after GnRH antagonist ganirelix treatment in women undergoing ovarian stimulation for assisted reproduction, with special reference to the prevention of ovarian hyperstimulation syndrome: preliminary report: short communication - Itskovitz-Eldor,J.; Kol,S.; Mannaerts,B. (Hum Reprod, 2000)