Comparing the effect of the order of cell Collection for Pap Smear on the results of cytologic Diagnosis

World wide, Cervical cancer comprises 12% of all cancers in women. In developed countries, routine cervical cytology tests resulted in a large decline in cervical cancer incidence. This study is a descriptive- analytical research to evaluate the order of cell sampling from exocervix and endocervix and compare final cytological diagnosis. Totally, 1129 smears were obtained by an Ayre spatula and an endocervical brush from patients who referred to Tehran health and birth control clinic. patients were divided into two groups. In 563 cases, the endocervical brush was used first, but in 565 cases the spatula was used first for sampling. Statistical testing showed that there is not any difference between groups regarding their age, age of marriage, partity, and type of contraception. More smears were obscured by blood when brush was used first (78 or 13/8% compared with 48 or 8.5%, P= 0.004) but we observed an insignificant difference between two groups and cytologic diagnosis. We observed higher proportion of atypical squamous cells of undetermined significance (ASCUS) detection in the spatula- first group (33 cases, 59%) compared with brush- first group (20 cases, 3.6%) which is insignificant (P=0.09). This study showed that the ability of squamous intraepithelial lesion (SIL) detection in spatula- first group (27 cases, 4.8%), was comparable to brush-first group (23 cases, 4.1%). Because reported SIL cases are higher when samples are first taken from exocervix and rate of blood contamination increases when samples are taken from endocervix (p=0.004), it is better to take samples first from exocervix for Pap Smear. This strategy increases the chance of diagnosis of cellular lesions of cervix.