Gynecologic Cytology
Specimen adequacy comes first
Before interpreting a single cell, decide adequacy. A liquid-based preparation needs roughly 5,000 well-visualized, well-preserved squamous cells (conventional smears historically required more); transformation-zone sampling (about 10 endocervical or squamous metaplastic cells) is reported but is not an adequacy requirement. "Satisfactory but limited by" is not the same as "unsatisfactory" - obscuring blood, thick inflammation, or air-drying that prevents interpretation drives an unsatisfactory call.
The Bethesda categories
Know NILM, ASC-US, LSIL, ASC-H, HSIL, AGC (qualify endocervical, endometrial, or not otherwise specified), AIS, squamous cell carcinoma, and other malignancy. Discriminating features matter: koilocytes with enlarged, irregular, hyperchromatic nuclei and perinuclear halos indicate HPV cytopathic effect (LSIL); ASC-US is for equivocal change when HSIL is not favored. High-grade cells are small with scant cytoplasm, high nuclear-to-cytoplasmic ratio, irregular membranes, and coarse chromatin. When low- and high-grade features coexist in one group, report the higher grade.
Traps
Questions love ASC-US versus LSIL in atrophic postmenopausal smears, where nuclear enlargement mimics dysplasia; reactive repair versus HSIL; and endometrial cells in a woman aged 45 or older, which require comment rather than a shrug. Tubal metaplasia and IUD change are classic distractors. AGC is not "a little atypia" - it is a glandular abnormality requiring correlation and usually colposcopy with sampling.
Worked example
A 34-year-old liquid-based preparation shows scattered squamous cells with enlarged nuclei, smooth contours, and slight hyperchromasia, but no halos and no high-N/C cells. The call is ASC-US, not LSIL: equivocal change without definite HPV cytopathic effect. Management follows risk-based algorithms, not reflexive upgrading of the category.