A comparison of two months pretreatment with GnRH agonists with or without an aromatase inhibitor in women with ultrasound-diagnosed ovarian endometriomas undergoing IVF.

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.