Niche, a newly described in the polish literature cesarean section complication, is defined as a triangular anechoic deficient of the uterine myometrium localized in the site of the scar after the incision of a typically performed low-transverse cesarean delivery. The aim of the paper is to provide an overview of the available literature on the diagnosis and symptoms of niche. Diagnostic evaluation of the niche comprises of visual diagnostic methods: transvaginal ultrasonography to localize the cesarean scar and contrast-enhanced sonography as the method of choice for measuring the depth of the niche, the residual myometrium thickness and the total myometrial thickness. The mechanisms of niche development have not yet been revealed, although, as suggested, it may be a coincidence of many factors as: closure technique, development of the lower uterine segment or location of the incision and wound healing. The symptoms related to the presence of a niche are: abnormal uterine bleeding, lower abdominal pain, infertility, urination problems and obstetrical complications which may be life-threatening for both the women and the fetus. The suggested relation between the niche and the occurrence of complications in future pregnancies, as uterine rupture and implantation of the gestational sack in the site of the diverticulum, are still unexplained.
Keywords: cesarean section; defect; niche; scar; ultrasonography.