“…Many variables apparently account for this discrepancy: the period of infertility, the control period, combined treatment, the type of contrast medium employed, and the selection of patients. In studies in which an oily contrast medium had been used the conception rate was 25 to 78 per cent (3,4,5,8,10,12,15) in comparison with 7 to 14 per cent when water soluble contrast media were used (3, who fulfilled the same selection criteria became pregnant in a 3 month period. We have fixed the waiting time for the HSG examination to three months and recorded how many of the patients who became pregnant in this period.…”