Agonist and antagonist coast
GnRH antagonist cycles are associated with a lower risk of OHSS and should be the protocol of choice in high-risk patients; and coasting is a useful protocol for prevention of OHSS.
Mohamed Aboulghar, M.D.
Volume 97, Issue 3 , Pages 523-526, March 2012
The use of GnRH-a in ovarian stimulation permitted stronger stimulation resulting in an increased incidence of OHSS. The first Cochrane review comparing GnRH agonist and GnRH antagonist protocols for ovarian stimulation showed no significant difference in OHSS rate between the two protocols, however, a recent Cochrane review showed a highly significant decrease in the incidence in OHSS rate in the antagonist protocol. Coasting is a commonly used procedure for preventions of OHSS. The optimum time to start coasting is when the lead follicle reaches 16 mm in diameter and hCG should be given when E2 level drops below 3000 pg/ml. Coasting may act by diminishing the functioning granulosa cell cohort. Administration of daily GnRH antagonist in high risk patients for OHSS who were down-regulated by GnRH-a resulted in rapid drop of E2 and decrease in incidence of OHSS. A series of patients who developed early OHSS were treated by daily GnRH antagonist injections, all embryos were cryopreserved. No progression to severe OHSS was observed.