The aim of the review was to summarize information on clinical manifestations, diagnostic features, as well as methods for correction of scar defects after cesarean section (CS) outside pregnancy. Lack of the scar after CS, niche, isthmocele are a myometrium defect in the area of scar after CS, which is most often detected by ultrasound, sonohysterography or magnetic resonance imaging and is manifested by postmenstrual bleeding from the genital tract. In some cases, it can cause menorrhagia, dyspareunia, pelvic pain, infertility, uterine rupture during subsequent pregnancy and childbirth. Conservative therapy or surgical treatment with laparoscopy, laparotomy or vaginal approach is carried out depending on the symptoms, size of the defect, the thickness of the residual myometrium, as well as the womans reproductive plans.