The effect of hysterectomy on the risk of an abnormal screening Papanicolaou test result

OBJECTIVE: Our aim was to determine the risk of cytologic abnormality on a screening Papanicolaou test for women greater than or equal to 50 years old with and without a uterine cervix. STUDY DESIGN: The effect of hysterectomy on abnormal screening Papanicolaou test rates was determined in a cross-sectional analysis of 21,152 women aged greater than or equal to 50 years who had screening Papanicolaou tests between January and August 1995. We then conducted a nested 1:1 case-control study of 172 case patients and 172 age-matched randomly selected control patients from the cohort. To control for potential confounders, conditional logistic regression was used to assess the effect of hysterectomy status on the risk of an abnormal Papanicolaou test. RESULTS: Compared with age-matched women with a uterine cervix, those who had a hysterectomy had a 10-fold lower risk of a screening Papanicolaou test abnormality (odds ratio 0.09, 95% confidence interval 0.02-0.24). The risk was further reduced among women taking estrogens (odds ratio 0.02, 95% confidence interval 0.004-0.14) compared with women not using estrogens (odds ratio 0.14, 95% confidence interval 0.04-0.56). CONCLUSIONS: The reduced risk of Papanicolaou test abnormalities among women aged greater than or equal to 50 years who have had a hysterectomy should be considered when individual patients are being counseled, screening guidelines are being formulated, and health care resources are being allocated.