Lack of transformation zone in cervical Pap tests, should it be a concern? A quality assurance initiative

Bethesda guidelines do not require presence of transformation zone (TZ) for a cervical Pap test to be deemed adequate. However, clinicians are concerned with specimens that are reported to lack TZ.

We analyzed 566 ThinPrep cases reported as negative for intraepithelial lesion or malignancy (NILM) with no cervical abnormality detected in previous 4 years (2007-2011). These cases were divided into two cohorts; those with TZ (ETZ) and those without TZ (NTZ). Patients' age, HPV status, time of sample collection (>14 days after last menstrual period), subsequent management, interval of subsequent Pap test (<1, 1-3, and >3 years), and result of subsequent examination were compared over a 5-year period.

The rate of abnormal Pap test on 5 year follow-up was not statistically significant (P < .9520) between cohorts. Our data demonstrates lack of statistical significance between the variables studied. Five year follow-up of all abnormal Pap smears were analyzed (93% ETZ and 7% NTZ). Of the ETZ group, 25% ASCUS remained as ASCUS and 75% were reported as NILM in subsequent Pap smears. Additionally, 75% of the LSIL were subsequently reported as NILM and 25% reported as ASCUS. One patient reported as HSIL underwent hysterectomy. Two Pap smears performed two years after surgery were negative. Within the NTZ group, one case of ASCUS was NILM upon follow-up.

Pap smears with NTZ were not at a higher risk for subsequent detection of cervical abnormalities, making earlier repeat testing unnecessary. Rescreening cases without TZ is neither cost effective nor necessary.