**3. Endometrial polyps**

Endometrial polyps are common, affecting more than 25% of women. They can be found within all ages [6, 7], and are common among infertile women with a prevalence up to 32% [8].

The potential mechanisms in which endometrial polyps can adversely affect fertility comprise mechanical interference and the release of molecules which adversely affect the spermatozoid transportation or the embryo implantation. Evidence shows increased levels of aromatase and glycodelin, a glycoprotein which inhibits the Natural Killer (NK) cells activity, resulting in a less receptive endometrium to implantation, inflammatory markers and decreased levels of HOXA-10 and 11 messenger RNA, which are known markers for endometrial receptivity [8, 9].

## **3.1 Diagnosis**

The investigation of polyps in women with RIF can be done through some of the following methods:


#### **3.2 Treatment**

Endometrial polyps surgical approach is controversial. The polyp size seems not to significantly affect pregnancy rates [12, 13]. Therefore, some studies have demonstrated that the resection of recently diagnosed polyps during ovarian stimulation cycle can decrease miscarriage rates and increase clinical pregnancy and live births rates, while others do not show such benefits. Lass et al. [14] showed that polyps smaller than 20 mm emerging during IVF can be expectantly managed without compromising clinical gestation and live births rates. However, in patients with RIF there is a recommendation for polypectomy prior to embryo transfer [3].
