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.