The aim of this study is to evaluate the effectiveness of short course of letrozole for endometrial preparation before hysteroscopic surgery for intracavitary lesions.

In the cycle subsequent to hysteroscopic identification of an endouteine pathology, patients who fitted with the inclusion criteria will be randomly divided into two groups; letrozole group (study group) and placebo group (control group). The randomization will be a stratified randomization with permuted blocking (the block size is randomly permuted among 2, 4, and 6) within each stratum. The only stratification variable will be by type of endouterine pathology. The randomization will be balanced (using a 1:1 treatment ratio) and will be carried out by a nurse through sealed, unlabeled, opaque envelopes containing computer-generated random numbers. The study will be double-blind (the participants, caregivers and investigators will be blinded to block size and group assignment).

Women in the letrozole group will be treated with letrozole (5 mg daily) for 10 days before hysteroscopic intervention while women in the placebo group will be treated with placebo for 10 days before hysteroscopic intervention in the early follicular phase of a natural cycle. In both groups, monopolar hysteroscopic surgery with glycine (1.5%) as uterine distension media will be used. Precise records of the duration of each surgical procedure, from the insertion to the removal of the resectoscope will be done.

Measurements of inflow, outflow, and amount of distension liquid absorbed by the patient will be taken meticulously. Intraoperative bleeding will be defined as "light" when bleeding does not interfere with surgery, "moderate" when bleeding required the coagulation of vessels, and "severe" when hemorrhage required immediate suspension of hysteroscopy. At the end of surgery, surgeon satisfaction with endometrial preparation using Visual Analogue Scale (VAS) and quality of visualization of the uterine cavity will be compared. Postoperative complications will be defined as the appearance of any complications occurring from the termination of the surgery to discharge.

Inclusion Criteria:

• Patients with endouterine pathologies, identified by office diagnostic hysteroscopy during the early endometrial proliferative phase (cycle days 7 to 8)

Exclusion Criteria:

• Presence of large submucous (type I, type II) or endocavitary (type 0) fibroids (according to the European Society of Hysteroscopy Classification of Submucous Fibroids) with a diameter exceeding 4 cm, for which preoperative treatment with GnRH agonists is indicated.
• Hormonal therapies in the previous 8 weeks (including the drug of the study).
• Uterine and/or concomitant adnexal pathologies (including malignancy) for which hysteroscopic surgery was not considered either safe or the method to resolve the problem.
• Cardiovascular, hepatic, or renal impairment.
• Allergy to letrozole.