Uterine factor comprises only 5% of the causes of infertility, however it is fundemantal in reproduction and should better be evaluated in detail during initial infertility work-up.  Uterine factor usually causes implantation failure or recurrent pregnancy loss. Comprehensive evaluation of uterus and endometrium might improve pregnancy rates in IVF by enhancing embryo implantation. Uterine factor can be categorized as either congenital or acquired.   Congenital Uterine Anomalies (Müllerian Anomalies) Women with Müllerian anomalies cannot be determined with certainty because some women with anomalies have normal reproductive outcomes. Among the congenital uterine anomalies, reproductive outcome vary depending on the specific anomaly, therefore accurate diagnosis is important (Table 1).    Table 1. Reproductive Outcome in Various Müllerian Anomalies

Uterine Anomaly	General Population	Infertile Population	≥2 Miscarriages	Infertility & Miscarriages
Overall	5.5%	8.0%	13.3%	24.5%
Arcuate	3.9%	1.8%	2.9%	No Data
Septate	2.3%	3.0%	5.3%	15.4%
Bicornuate	0.4%	1.1%	2.1%	4.7%
Didelphys	0.3%	0.3%	2.1%	2.1%
Unicornuate	0.1%	0.5%	0.5%	3.1%

Data from Chan et al., 2011 (94 Studies, 89861 Women)   None of the classification systems is ideal, therefore regardless of the classification system used, a patient’s uterine anomaly should be described as precisely as possible. Accurate characterization of the uterine anomaly is possible with Transvaginal Sonography (TVS), Hysterosalpingography (HSG), Saline Infusion Sonography (SIS), Hysteroscopy, 3-Dimentional Sonography, MRI and combined Laparoscopy and Hysteroscopy. Treatment of the uterine anomaly depends on the clinical situation and/or the severity of the anomaly. Müllerian anomalies are not associated with infertility but diminished live birth rate.     Acquired Uterine Anomalies   -Endometrial Polyp Polyps have a high prevalence rate (15-32%) among infertile women so it is important to rule them out early in the infertility work-up (Dreisler et al., 2009). TVS, SIS and HSG usually reveal the polyp. Although the effect of polyp on fertility is still controversial, overall body of evidence indicates a benefit of prophylactic polypectomy of any size for infertile women.        -Thin Endometrium Endometrial thickness ˂7 mm might be a negative prognosticator for fertility. It might be due to intrauterine adhesions and better be evaluated with hysteroscopy.   -Intracavitary Fluid Collection Fluid collection in endometrial cavity might be associated with tubal factor, PCOS and endometriosis. It might impede embryo implantation. In such cases, embryo freezing or cancellation of the cycle may be considered.    -Myoma Uteri Studies examining the potential effect of fibroids on fertility concluded that submucosal fibroids have a negative impact on fecundity.  Hysteroscopic myomectomy is beneficial, improves pregnancy and live birth rates. Intramural fibroids also may have a negative impact on fecundity, especially those impinging into the uterine cavity and/or >4 cm however, enhancing effect on fertility of intramural myomectomy has not been clearly established.       -Adenomyosis Effect of adenomyosis on fertility is diffcult to estimate since it is commonly associated with endometriosis and/or fibroids. Adenomyosis can be diffuse or focal (adenomyoma). When adenomyosis is diagnosed in an infertile woman, surgical intervention might be performed considering female age and/or previous fertility treatment outcomes.      -Intrauterine Adhesion Intrauterine adhesions in any amount are associated with infertility, amenorrhea/hypomenorrhea and/or recurrent pregnancy loss. In diagnosis; TVS, SIS, HSG and office hysteroscopy are useful. The aim in treating intrauterine adhesions is to restore a normal cavity and to prevent reformation of adhesions. Preferred treatment of adhesions should be hysteroscopic adhesiolysis with scissors and blunt dissection. Following adhesiolysis estrogen treatment, insertion of foley catheter/IUD/uterine stent/adhesion barriers are applicable however, their effect on preventing re-development of adhesions has not been clearly defined.           In conclusion, uterus is a critical reproductive organ. Treatment of uterine factor infertility is usually performed successfully with hysteroscopy. Judicious use of hysteroscopic septum resection, adhesiolysis, submucous myoma extirpation and polypectomy make a positive impact on a woman’s fecundity and fertility treatments.