Endometrial polyps are localized overgrowths of endometrial glands and stroma within the uterine cavity.In determining uterine receptivity, the endometrium and uterine cavity are two important factors that are most successfully evaluated by hysteroscopy (11, 12). They are frequently asymptomatic and therefore may remain undetected (13).
The prevalence of endometrial polyps is considered to be higher in infertile women (1, 14).The polyps can be millimeters to centimeters in size, single or multiple, and sessile or pedunculated,( 15). Some studies suggest that polyps are associated with infertility (15), but only one randomized controlled trial confirms the association. (7). It seems that many of the risk factors for endometrial polyps can be underlied by unopposed or excess estrogen exposure,as in the case of ovarian stimulation during IVF(4, 9, 10). Molecular mechanisms, containing the over expression of estrogen and progesterone receptors (25), Polyps may adversely affect fertility by mechanically interfering with sperm transportation or as space-occupying lesions impeding embryo implantation (4, 5). Endometrial polyps may also induce local inflammatory changes (19, 20) or produce glycodelin (21), The glands and stroma in endometrial polyps are unresponsive to progesterone stimulation, leading to defective implantation at the site of the polyp (20, 22)With respect to endometrial receptivity, HOXA10 and HOXA11 mRNA expression are decreased in endometrium obtained from uterine cavities containing polyps compared with normal cavities, (15).
In this context, hysteroscopic polypectomy remains the criterion standard for both diagnosis and treatment of endometrial polyps (1, 15). Previous studies have shown that resection of endometrial polyps can improve natural conception rates, particularly in patients with unexplained infertility (16). In one retrospective study of 78 patients by Varasteh et al , a pregnancy rate of 78.3% was noted after polypectomy compared with a pregnancy rate of 42.1% in patients with normal uterine cavities (6). Removal of polyps at the uterotubal junction results in the greatest chance of pregnancy (57.4%) based on a retrospective study of polyp location in 230 infertile women [23]. The best evidence for polyps as a cause for infertility comes from a well designed RCT of 215 infertile women with polyps planning to undergo intrauterine insemination (IUI) [24]..Significantly higher pregnancy rates were demonstrated in women who had hysteroscopic polypectomy
Pregnancy rates are also improved in patients undergoing hysteroscopic polypectomy before undergoing intrauterine insemination (IUI) (9 ,15).Similarly, a previous retrospective study showed that natural conception rates were increased among infertile women who had hysteroscopic polypectomy compared with those who had hysteroscopy, but were found to have a normal cavity (78 versus 42.1%) (25).These findings were confirmed by another independent study, which reported pregnancy rates of 40.7% and 22.3% in patients who, respectively, did and did not undergo polypectomy before IUI (2). The resection of endometrial polyps diagnosed before starting IVF-ET cycles are suppored by current evidence. (1). However, there is limited evidence about the optimal time interval between hysteroscopic polypectomy and initiation of a FET cycle. In a retrospective study of 60 patients, Eryilmaz et al. compared the ovarian stimulation and pregnancy outcomes of 29 and 31 patients who got IVF <6 months and 6 months, respectively, after hysteroscopic polypectomy . It is concluded that there is no relation between the IVF outcomes of the study cohort and the initiation time of the IVF after the hysteroscopic polypectomy (8). Whereas our study stratified the time period between polypectomy and FET cycle start by the number of intervening menstrual cycles. It is suggested by some studies that higher implantation and pregnancy rates after mild endometrial injury in the menstrual cycle preceding IVF (27 ). Group 1 in the present study represents such a clinical scenario, but the implantation and pregnancy rates of group 1 were similar to those of groups 2,3 and4. The present study is not without limitations. All hysteroscopic polypectomy cases were performed in the operating room with the use of a monopolar resectoscope. It remains to be confirmed whether the observed IVF-ET cycle outcomes would remain unchanged if polypectomy were operated in the office setting or with other resection methods, such as bipolar electrode excision (29) or hysteroscopic morcellation (30,31). Although our analysis of FETcycle outcomes was stratified on the basis of the number of menstrual cycles between hysteroscopic polypectomy and FET cycle start, Furthermore, it must be noted that reasons for delaying FET were largely logistical or personal. Finally, its conclusions should be interpreted with caution and should be subject to larger prospective settings, because the study was retrospective in nature.