Effect of aromatase inhibitor (letrozole) with long agonist protocol on the results of ICSI/ET in females with minimal and mild endometriosis

Background: ICSI/ET in endometriosis patients has poor outcome by traditional protocols. The key enzyme in the biosynthesis of estradiol, aromatase, has been demonstrated within endometriosis. Combined administration of aromatase inhibitor and GnRH-agonist may efficiently suppress estrogen biosynthesis through a combined pituitary, ovarian and local factors in the implants. Objective: Evaluate the effect of using letrozole in improvement of the results of ICSI/ET in endometriosis women with long agonist protocol. Patients: Sixty infertile women with minimal and mild endometriosis according to the revised American Fertility Society classification were scheduled for ICSI/ET. Methods: Women were randomized into two groups. Group 1: using the traditional luteal long agonist protocol using triptorelin 0.1 and Group 2: using letrozole 5 mg/day started 5 days after the start of GnRH agonist for 5 days. All patients were monitored with day 6 serum estradiol level and estradiol at day of HCG. The number of days of stimulation, number of retrieved oocytes, number of MII oocytes, cleavage rate, and pregnancy rate were studied in both groups. Results: Days of stimulation were significantly higher in the treated group (p=0.019). Oocytes number was not affected (10.57 ±6.14) and (11.21 ±6.41) (p=0.516) in groups 1 and 2 respectively also, the number of embryos was not affected (p= 0.955). Nine (32.1%) pregnant cases of 28 were in the first group while 8 from 27 in the second group (29.6%). Conclusion: Letrozole significantly affected days of stimulation of ICSI cycle in endometriosis patients without affecting pregnancy rate.