The ABCs of TBS: A Novice's Guide to the Bethesda System

The Pap smear is the most successful cancer screening method known, playing a pivotal role in the dramatic decrease in incidence of and mortality from invasive cervical cancer. The Bethesda System, sometimes called TBS, for reporting cytologic diagnoses of cervicovaginal samples originated from a conference held by the National Cancer Institute in 1988. The Bethesda System provides a means of communicating Pap smear diagnoses to clinicians in a standardized manner and has largely supplanted previous systems, such as the Papanicolaou classification. This article provides basic information about premalignant and malignant lesions involving the cervix and their classification under the Bethesda System. A brief overview of relevant cervical anatomy and histologic and cytopathologic features is included.