Pathophysiology of the Papanicolaou Smear

Age and hormone levels affect cervical anatomy and physiology. Awareness of hormonal effects on the transformation zone (TZ) of the cervix is particularly important when interpreting the Papanicolaou (Pap) smear. The TZ represents the transition from stratified squamous epithelium to columnar epithelium. Dysplasia of the cervix develops within this TZ (Mishell). When the squamocolumnar junction (SCJ) moves in response to advancing age and changing hormonal status, the area between the original SCJ and the new SCJ is termed the TZ (Lichtman).

The hormonal status of the patient may therefore affect your ability to obtain a satisfactory specimen for the Pap smear. (Refer to pathophysiology of vaginal secretions, the TZ, and physiology of the menstrual cycle.) Endocervical mucosa ascends with decreasing ovarian activity. Ectropion is more common during a woman's childbearing years because the endocervical glands lie just below the internal os and extend to just below the external os. (Refer to anatomy of the cervix.) With ovarian failure the TZ moves upward, so that the SCJ may be high within the endocervical canal in a postmenopausal woman. This makes the endocervical component of the Pap smear difficult to obtain. Also, coitus may temporarily shrink the TZ (Lichtman).