colposcopy, medical examination of the epithelial tissues of the cervix, vagina, and vulva with a special lighted magnifying instrument called a colposcope. Colposcopy is used when the Papanicolaou test (or Pap smear; cervicovaginal cytology) suggests the possibility of cancer of the uterine cervix. It helps to detect precancerous abnormalities and identifies in which areas a biopsy should be performed for a definitive diagnosis to be made.