The Pap test is not a diagnostic test; it is only a screening test for cervical cancer or cervical changes that are precancerous. The low sensitivity associated with the Pap smear test limits its usefulness. Limiting factors include:
- Inadequate collection
- Sample preparation errors
- The possibility of inaccurate microscopic examination (although numerous safeguards are built into the process in an attempt to prevent inaccuracies)
Colposcopy, biopsy, and/or endocervical scraping are used to diagnose cervical cancer. A colposcopy is a diagnostic procedure that examines an illuminated, magnified view of the cervix, vagina, and vulva. The technique may allow for a direct biopsy of the tissue area for further pathological examination.
Other types of cervical biopsies may be performed such as an endocervical curettage, in which a narrow instrument called a curette is used to scrape tissue from inside the opening of the cervix. In addition, a cone biopsy, or conization, may be used to remove a cone-shaped piece of tissue from the cervix. In a cold knife cone biopsy, a surgical scalpel or laser is used to remove the tissue. A loop electrosurgical excision procedure (LEEP) is a cone biopsy using a wire that is heated by an electrical current. Cone biopsies can be used to determine whether abnormal cells have invaded below the surface of the cervix. They also can be used to treat many pre-cancers and very early cancers.