Single versus double intrauterine insemination in multi-follicular ovarian hyperstimulation cycles: a randomized trial

BACKGROUND: The rationale for double insemination is to create the opportunity for a longer fertilization period as follicle rupture may occur over a wide interval (similar to 22-47 h) after hCG administration in ovarian hyperstimulation (OH) with intrauterine insemination (IUI) cycles. This randomized study evaluates the effectiveness of single versus double IUI in only OH cycles with multi-follicular development. METHODS: We conducted a single center trial, 228 eligible patients were randomized for this study on the day of hCG. Only cycles with multi-follicular development without premature luteinization (progesterone levels >1 ng/ml on the day of hCG), were included in the study. Multi-follicular development has been defined as at least two dominant follicles reaching minimum >= 15 mm diameter in which one of them is >17 mm. OH cycles with more than five dominant follicles (>15 mm in diameter) were excluded from the study. In the single IUI group (Group 1 = 112 patients) IUI was applied 36 h after the hCG injection and in the double IUI group (Group 2 = 114 patients) the first IUI was performed 18 h after hCG administration and the second IUI was performed 40 h after hCG administration. The primary end-point is to compare live birth rates (LBRs) between single and double IUI arms. RESULTS: LBRs were 10.7% (12/112 patients) in the single IUI group and 12.3% (14/114) in the double IUI group and the difference was not statistically significant (P = 0.835, OR = 1.16, 95% Cl: 0.51-2.64). In the unexplained infertility group the LBR was 11.1% (5/45 patients) with single IUI and 18.4% (9/49) with double IUI (P = 0.393). In the mild male factor group this rate was 10.4% (7/67) and 7.7% (5/65) in the single and double IUI groups, respectively (P = 0.764). CONCLUSION: Our study did not find any difference in LBRs between single and double IUI groups in OH cycles with mufti-follicular development. To the best of our knowledge this is the first report with this kind of study design.