The literature tells to supply umbilical hernia with a mesh, that overlaps 5-6 cm in each direction. To achieve this overlap an extensive taxidermy is necessary, which causes a big operation trauma. An umbilical hernia is an extended physiological stoma and compared to an incisional hernia has no risk to rip further. Therefore the researchers act on the assumption that this generous overlap is not necessary. For a short time there is a new mesh available, which combines all the necessary requirements as elasticity, effective porousness and a structure of monofilaments with MRI visibility. In a randomised clinical trial two sorts of meshes, a conventional PVDF(polyvinylidene fluoride) mesh (DynaMesh-CICAT) and a MRI visible PVDF(polyvinylidene fluoride) mesh (DynaMeshVisible) shall be compared.The investigators postulate that there is no difference between the two groups concerning complications, relapse and life quality after 4 weeks and 12 months. Altogether the goal of the study is to determine the exact position of the mesh in vitro.