LAUSR

RESEARCH QUESTION Does the addition of an aromatase inhibitor improve IVF outcomes in women with endometriomas when pretreating them with gonadotrophin-releasing hormone agonists? DESIGN Retrospective two-centre cohort study involving 126 women aged 21-39 years who failed a previous IVF cycle and all subsequent embryo transfers and had sonographic evidence of endometriomas. Women were non-randomly assigned to either 3.75 mg intramuscular depo-leuprolide treatment alone or in combination with 5 mg of oral letrozole daily for 60 days prior to undergoing a fresh IVF cycle. Main outcome measures included clinical pregnancy rate and ongoing pregnancy rate after 24 weeks' gestation. RESULTS Prior to treatment, antral follicle count (AFC), basal serum FSH and endometrioma diameter did not differ between groups. After treatment, AFC differed between letrozole and non-letrozole-treated groups (10.3 ± 2.0 versus 6.4 ± 2.5; P = 0.0001), as did mean endometrioma maximum diameter (1.8 ± 0.4 cm versus 3.2 ± 0.8 cm; P = 0.0001). At IVF, the gonadotrophin dose used was significantly lower in letrozole-treated subjects (2079 ± 1119 versus 3716 ± 1314; P = 0.0001), the number of mature oocytes collected was greater (9.1 ± 2.4 versus 4.0 ± 1.7; P = 0.0001), as were the number of two-pronuclear embryos and number of blastocysts. The clinical pregnancy rate was significantly higher in the letrozole-treated group (50% versus 22%, P = 0.003), as was the live birth rate (40% versus 17%, P = 0.008). CONCLUSIONS The combination of depo-leuprolide acetate monthly for 60 days combined with daily letrozole has better clinical outcomes at IVF in women with endometriomas than depo-leuprolide acetate treatment alone.