Clinical determinants and smear characteristics of unsatisfactory conventional cervicovaginal smears.

Objective: To investigate clinical and cytomorphological determinants of unsatisfactory conventional Papanicolaou (Pap) smears.
Study Design: Records of 82,108 conventional cervicovaginal smears received over a ten-year period were retrieved. The significance of clinical determinants, viz. age (<45 or ≥45) and history of hysterectomy, radiotherapy (RT) and chemotherapy (CT), with respect to unsatisfactory outcomes was evaluated using univariate and multivariate analysis by logistic regression. Reasons for unsatisfactory results, i.e. cellularity, obscuration by blood or inflammation and drying artifact, were compared in the women managed by hysterectomy/RT/CT with those without these histories, using Chi square/Fischer's exact test.
Results: The overall unsatisfactory rate on conventional cervicovaginal cytology was 4.9%. For post-hysterectomy/RT/CT smears it was 12.5% while it was 4.6% for those without these histories. Age ≥45, and history of hysterectomy, RT or CT were all found to be significant for unsatisfactory outcomes (P<0.001), with the highest odds ratio for RT (2.81). Inadequate cellularity was the major reason for unsatisfactory cytology in both the treatment and non-treatment groups. Marked obscuring by blood was significantly more frequently associated with unsatisfactory tests in the treatment group (mainly in the post-radiotherapy smears) as compared to the control group (P<0.05). Multiple reasons were more commonly present in unsatisfactory smears from treatment group as compared to the control group (P<0.001).
Conclusions: Older age and history of hysterectomy, RT or CT have a significant bearing on unsatisfactory outcome of Pap tests. Inadequate cellularity and obscuring blood are the main morphological determinants of unsatisfactory smears.
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