Value of measuring serum FSH in addition to serum estradiol in a coasting programme to prevent severe OHSS

BACKGROUND: Withholding gonadotrophins (coasting) can reduce the risk of severe ovarian hyperstimulation syndrome (OHSS) in patients having assisted reproduction therapy. This requires daily serum estradiol (E-2) measurements, which occasionally have been seen to decline suddenly and sharply. METHODS: To increase the sensitivity of the coasting programme we measured serum FSH in parallel with E-2 in patients at risk of developing OHSS. RESULTS: Out of a total of 1240 cycles, 106 were coasted and in 89 both serum E-2 and FSH were measured at least twice during the coasting period. One case of late severe OHSS was encountered in the study group. The serum FSH declined by a rate of 24.3+/-4.5% per day. Serum E-2 level reached a 'safe level' of <10 000 pmol/l when the serum FSH declined to 5 IU/l or less. CONCLUSION: The results from this study show that measuring serum E-2 and FSH can assist in predicting the point at which serum E-2 has declined to a level safe enough to administer the trigger HCG.