Hysterosalpingography with oil contrast medium enhances fertility in patients with infertility of unknown etiology

Previous studies have suggested increased fertility rates following hysterosalpingography (HSG) using oil as compared with aqueous contrast medium. To compare the possible fertility-enhancing effects of two agents used for HSG, this prospective randomized study evaluated the subsequent fertility rates in 121 patients who underwent HSG, in which either oil or aqueous contrast medium was used. After random assignment to either agent, patients were observed for four menstrual cycles after HSG without resorting to any therapy other than clomiphene citrate where indicated. The pregnancy rates for the four cycles after HSG were compared with chisquare analysis in the total study and in the diagnostic subgroups. The subgroup with infertility of unknown cause had a significantly higher pregnancy rate after HSG with oil than after HSG with aqueous contrast medium. No significant difference was seen for any other subgroup or for the overall cohort.