• cervix uteri;
  • infertility;
  • insemination;
  • pregnancy rate;
  • urinary bladder


Aim:  The aim of the present study was to evaluate the efficacy of passive uterine straightening during intrauterine insemination (IUI).

Material and Methods:  A randomized controlled trial was conducted at Zeynep Kamil Maternity and Pediatric Research and Training Hospital. Participants were 460 women with unexplained infertility. Interventions were IUI by passive straightening of the uterus by means of bladder filling, or IUI performed with an empty bladder. Main outcome measures included pregnancy rate and difficulty of IUI.

Results:  Four hundred and sixty couples were allocated: 230 couples were allocated to the full bladder group, and 230 couples were allocated to the empty bladder group (control). The pregnancy rate was higher in the full bladder group than in the empty bladder (control) group (P = 0.03, 13.5% vs 7.4%; relative risk [RR] 1.95 for pregnant patients; 95% confidence intervals [CI] 1.048–3.637). The risk of undergoing difficult IUI was higher in the empty bladder group than the full bladder group (P < 0.001; 10.0% vs 37.8%, RR 0.18 for difficulty IUI; 95% CI 0.11–0.30). The clinical pregnancy rate was also higher in the group of patients who had easy IUI than in the group of patients who had difficult IUI (P < 0.05, 12.7% [42/331] vs 5.5% [6/110]); RR 2.51 for pregnancy; 95% CI 1.04–6.09).

Conclusion:  Passive straightening of the uterus makes the procedure less difficult and improves the clinical pregnancy rate.