Estrogen has a predictable effect on the cells of the cervix and the absence or presence of estrogen can be determined on the Pap smear.

In women of childbearing age, or menopausal women taking estrogen replacement therapy, the Pap would be expected to show an “estrogen effect,” and its’ absence would be a curiosity, though probably not dangerous.

In menopausal women not taking estrogen replacement therapy, the presence of detectable “estrogen effect” would suggest some non-ovarian source of estrogen and the long-term effects of unopposed estrogen should be considered.