Müllerian anomalies (MA) are associated with infertility and affect approximately 6.3% of the infertile population. The estimation of the frequency of MAs is not without controversy because it depends on the diagnostic method used and sometimes on the established diagnostic criteria. This pathology is associated with abortion during the second trimester in addition to other complications that include preterm labor, fetal malpositions and an increased rate of caesarean section, although some patients may remain asymptomatic. An association between MA and endometriosis has been described and in particular the case of the septum uterus, therefore it is difficult to establish whether the reproductive results of women with MA tdepend only on the uterine factor or also on the quality of the oocytes.

The main reproductive problems associated with these malformations include, abortion , recurrent abortion ectopic pregnancy and preterm delivery . The experience gained from oocyte donation shows that these women are pregnant less, even with the transfer of good quality embryos. The hypothesis of this poor uterine receptivity is in the poor endometrial vascularization that can decrease embryo implantation. The reason for infertility in women with AM includes decreased muscle mass, decreased endometrial vascularization, decreased capacity of the endometrial cavity, less receptive areas (septum). The lower fertility observed in some women with Müllerian malformations has been partially explained by its tubal factor and its association with endometriosis, with a higher prevalence in them, compared to patients without malformations.

Studies have confirmed an irregular differentiation and estrogenic maturation of the endometrium lining the uterine septum or its internal structure, which has less presence of connective tissue and more muscle mass. Given the confusion generated if the unfavorable reproductive result is due to oocyte quality or endometrial receptivity, it is necessary to use a model that guarantees oocyte / embryo quality and this is offered by oocyte donation. The aim is to evaluate the implantation rate in women with MA who receive donated oocytes compared to women without MA.

Inclusion Criteria:

• Women included in the oocyte donation program at IVI Vigo and Valencia 2000-2019.
• Sperm count greater than 1,000,000 per ml.
• Transfer on day 5 of embryo development of at least one good quality embryo.

Exclusion Criteria:

• Testicular biopsy.
• Any indication for preimplantation genetic diagnosis or screening.
• Uterine fibroid greater than 4 cm.
• Presence of ultrasound or diagnosis by HSG or laparoscopy of hydrosalpinx uni or bilateral.
• Recurrent abortion.
• Any abnormality of the uterine cavity other than MA: submucosal myoma, endometrial polyp, or uterine synechiae.

Women with Müllerian anomalies who have received an oocyte donation. The diagnosis of Müllerian anomalies is established when a cavity is demonstrated uterine abnormality with any of the defects described in the American classifications or European in transvaginal ultrasound, hysteroscopy or hysterosalpingography (HSG). The differential diagnosis in case of doubts is established with 3D ultrasound, MRI or hystero / laparoscopy. All the septa have been resected prior to performing the OVODON cycle.