Via is an attractive alternative to pap smears for its ease of use low-cost and fewer physician visits. Developing countries often lack the necessary resources to use the pap smear as a screening tool for cervical abnormalities chary and rohloff 2014 via is carried out by using 3-5% dilute glacial acetic acid which is liberally applied to the cervix with a cotton-tipped swab or cotton balls or using a 2 x 2 inches gauze or with a sprayer so that it covers the entire cervical surface including the external os. The two main purposes of applying acetic acid are first to conduct inspection of the entire new sqaumo-columnar junction and second to detect and evaluate the areas of abnormal or atypical transformation zone.
Visual inspection using lugols iodine vili also known as schillers test uses lugols iodine instead of acetic acid. Advantages of vili are that it is easily available can be easily performed by paramedical workers and doctors test results are immediately available and hence see and treat policy can be used low cost. Iodine negative areas include columnar epithelium lacking glycogen patchy uptake peripheral areas due to cervicitis and immature metaplasia. Mustard yellow areas with distinct borders suggest more severe disease. The colour changes with vili are more easy to appreciate than the changes after via sarian derchain et al. 2005 bhatla mukhopadhyay et al.
2007 abnormal transformation zones such as those with cin or invasive cancer contain very little or no glycogen. The degree of differentiation of the cells in a pre-neoplastic squamous lesion determines the amount of intracellular glycogen and the degree of staining observed figure 2.8 olaharski sotelo et al. 2005 the papanicolaou test also called pap smear pap test cervical smear or smear test is a screening test used to detect potentially pre-cancerous and cancerous processes in the endocervical canal transformation zone of the female reproductive system. George papanicolaou in 1920 began to use pap technique for examining vaginal smears under the microscope to study human vaginal cytology.
His wife mary was his first and long term human subject. Dr. Papanicolaou was a founding father of the field of exfoliative cytology. In the 1940s when the pap smear was first introduced cervical cancer was the number one killer of women. Since then pap smear a standard cervical cancer screening test for all women has greatly reduced the morbidity and mortality caused by cervical cancer especially in the developed countries. A speculum is used to open the vaginal canal which allows the collection of cells from the outer opening of the cervix of the uterus and the endocervix during pap smear collection figure 2.9 the cells are examined under a microscope for abnormalities.
The test aims to detect potentially pre-cancerous changes called cervical dysplasias. The older traditional pap technique involves direct transfer of the cervical cells collected on to a microscopic slide for evaluation. In a more recent technique the cells collected are released into a vial of liquid preservative lbc that is then used in the cytology lab to produce a slide for microscopic evaluation of the cells. Although the traditional method may introduce confounders such as blood and other debris to the slide which may make interpretation more difficult both conventional cytology cc and liquid-based cytology lbc have been shown to have similar sensitivity and specificity for moderate dysplasia lsil or hsil. In addition both types of cytological screening are considered acceptable by the american college of obstetricians and gynecologists acog results from cervical cytology specimens are presently reported according to the 2001 bethesda system classification solomon davey et al.
2002 conventional pap: cervical cell sample is smeared directly onto a microscope slide after collection. Liquid based cytology—the pap smear sample is put in a bottle of preservative for transport to the laboratory where it is then smeared on the slide. The examination of the cervix vagina and vulva is done with an instrument that provides strong light and magnifies a field allowing specific patterns in the epithelial surface layer and surrounding blood vessels to be examined. This can be done with a colposcope an expensive specialized piece of equipment figure 2.10a abnormal looking cervix after via or vili or those with an abnormal cytology are subjected to colposcopy where with via a representative abnormal tissue bit is biopsied for histopathological evaluation massad einstein et al.
2013 biopsy is the removal of small samples of abnormal tissue for microscopic examination to achieve a diagnosis. Biopsies can be taken from areas of the cervix that are via-positive or from areas that appear suspicious for cancer. If a lesion or abnormal structure of the cervix is not visible to the naked eye colposcopy can assist in pinpointing the site or sites where one or more biopsies should be taken. Special biopsy forceps are required figure 2.10b and training is necessary. After examination a biopsy is classified as normal cin or as invasive carcinoma. Specific genomic changes appear to be mandatory events for the development of cervical cancer hildesheim schiffman et al.
1994 85% of anogenital carcinomas exhibited copy number changes in specific chromosomal regions. Heselmeyer-haddad sommerfeld et al. 2005 fish is a technique that detects nucleic acid sequences by a fluorescent probe that hybridizes specifically to its complementary target sequence within the intact cell. It is a technology that has been widely recognized as a promising molecular and biomedical optical imaging tool to screen and diagnose cervical cancer moscicki shiboski et al.
1998 the introduction of microarray technologies in the 1990s has provided genome-wide strategies for searching tens of thousands of genes simultaneously. Studies to discover the molecular markers for accurate cervical cancer screening using cdna microarray studies have shown that the global gene expression patterns separated normal cervical tissues and lsils from cervical cancers and most hsils. The extent of gene over expression increased as the lesions progressed from lsils or hsils and finally to cancer chen miller et al. 2003
