A comparison of modified and standard pap staining methods in the assessment of cervical smears at Kenyatta national hospital

Abstract

Invasive carcinoma of the cervix is one of the most common cancers in the world. Cervical cancer is preventable by screening methods. The traditional screening method is the Pap smear. As practiced conventionally Pap stain is expensive utilizing a considerable amount of alcohol and consumes a lot of time. Several Pap modifications have been made to reduce both alcohol use and time and they have proved to be cheaper and timely and reveals improved morphological staining quality with no diagnostic compromise. Objective: To compare modified and standard Papanicolaou (Pap) staining methods in the assessment of the cervicovaginal smears in respect to cytomorpholocical features, cytodiagnosis, reagents, time and cost. Design A descriptive cross sectional study Study area Gynecology clinic 18, FP clinic 66 and cytology laboratory at KNH Study population Women attending the study areas at KNH and who were eligible for a pap smear. Methods: One hundred and sixty two coded paired cervical smears were prepared by liquid based method. One set of smears was stained by the standard Pap staining protocol (SP) and the other by the modified Pap protocol (MP) in which alcohol was replaced by 0.5% acetic acid. The smears were blinded and examined by the investigator and then the pathologists and decoded. Each pair of smears was compared and the two protocols were analysed for staining quality and cytodiagnoses statistically by use of Chi square. Results: The study showed that the time taken to stain each bunch Pap smear slides in the modified Pap method is 3 ± 0.5 minutes while in the standard Pap method the time taken was 20 ± 0.5 minutes for the same number of slides. In MP the cost of alcohol used per smear was Ksh 18.50 and Ksh 123.45 per smear in the SP. The standard Pap method had 14 (8.8%) unsatisfactory cytoplasmic staining, 102 (64.2%) were satisfactory and 43 (27.0%) were excellent while Modified Pap method had 10 (6.3%) unsatisfactory cytoplasmic staining, 53 (33.3%) satisfactory and 96 (60.4%) were excellent. The nuclear staining was hazy in 79 (49.7%) and distinct in 80 (50.33%) in the standard Pap, while in the modified Pap, the nuclear staining was hazy in 54 (34%) and distinct in 105 (66%). The results for the cytodiagnosis concurred in both the modified and standard Pap methods. Conclusions: The modified Pap staining method is simple, low cost and better in the staining of the cervical smears and can therefore be used as alternative to the standard Pap method in the screening for cervical cancer. Recommendations: Modified Pap method should be introduced for the screening of cervical cancer in low resource settings.