The addition of GnRH antagonists in intrauterine insemination cycles: a pilot study

This prospective study was designed to assess whether the use of GnRH antagonists can improve the success rate of controlled ovarian stimulation (COS) in intrauterine insemination (IUI) treatments.

Eighty patients were divided into two groups: GnRH antagonist group (Group A, n=40) and control group (Group B, n=40). Patients in Group B underwent COS with recombinant Follicle Stimulating Hormone (r-FSH, 50-75 IU/d) only, while patients in Group A were administered r-FSH (50-75 IU/d) plus cetrorelix (0.25 mg/d, starting when ≥ 2 follicles ≥ 14 mm were detected on ultrasound scan). In both groups a single insemination was performed 36 hours after human Chorionic Gonadotropin (hCG, 250 mcg) administration. The primary outcome was clinical Pregnancy Rate (PR). Secondary outcomes were ongoing PR, incidence of Premature Luteinization (PL), number of follicles with mean diameter ≥ 16 mm and between 11 and 15 mm on the day of hCG administration, miscarriage rate, cycle cancellation rate, total amount of r-FSH used and duration of treatment. Student's t test and Chi-square test were used (p < .05 statistically significant).

A total of 146 cycles were performed (Group A: n=72; Group B: n=74). A trend towards higher PR in Group A was detected, although it was not statistically significant (Clinical PR: 18.05% vs 10.81%). The number of follicles ≥ 16 mm was significantly increased in Group A. The incidence of both premature LH surge and premature luteinization (PL) was significantly higher in Group B. No significant differences were found in the duration of the stimulation protocol, and in the total amount of r-FSH administered.

The addition of GnRH antagonist in COS/IUI protocol significantly increases the number of mature follicles. However, this multifollicular recruitment is not linked to a significantly higher PR.