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T-shaped uterus (U1 in the ESHRE classification), initially described in cases of in-utero exposure to Distilbene®, is a rare uterine malformation characterized by a small uterine volume alongside an excess of myometrium in the uterine side walls. The gold standard for diagnosing this malformation is 3D ultrasound, sometimes accompanied by sonography. The presence of a U1 uterus tends to be associated with decreased fertility and an increased rate of miscarriages. It also appears to be associated with an increased rate of implantation failure in medically assisted reproduction. Enlargement surgery (or metroplasty), which is performed by hysteroscopy, is the standard treatment. It does not cause any harm, is easy to perform, and gives good anatomical results. The impact of surgery on fertility and obstetric prognosis appears to be positive. Nevertheless, the data in the literature are poor, with studies having low levels of evidence. No randomized trials have been conducted to date. Based on these data alone, it is therefore difficult to systematically recommend metroplasty in order to improve fertility or the obstetric prognosis. In our opinion, in view of the nonetheless positive results in the literature, each situation must be assessed on a case-by-case basis and surgery can be proposed, especially when no other cause has been found.