A dilator (or dilatator) is a surgical instrument or medical implement used to induce , that is, to expand an opening or passage such as the cervix (see cervical dilator), urethra, esophagus, or vaginal introitus. Dilators may also be used to increase the size of a surgical incision, for example during insertion of a venous catheter.
Types of dilators include vaginal dilators, rectal dilators, and urethral sounds.