Pap smear


Should be done in all women who are or who have been sexually active or who are 18 years and older.

55 million tests each year in the US, and 3.5 million, or 6%, are associated with abnormal results that require medical follow-up (NCI).

Presence of endocervical cells usually considered an indicator of an adequate sample.

Not necessary in women who have had a complete hysterectomy, unless the surgery was performed for cervical cancer or its precursors.

Because of the rarity of cervical cancer in women younger than 21 years of age Pap smear is not encouraged for women younger than 21 years.

Overall false negative rate is at least 20%.

HPV infected women typically have normal Pap smears.

HPV related changes include atypical squamous cells of undetermined significance and low-grade squamous intraepithelial lesions commonly seen in Papanicolaou test results in adolescents.

99% of cervical cancers contain the genes of HPV’s, most commonly 16, 18, 3, 33,35, 39, 45, 51, 52, 56, 58, 59 and 68.

False negative and false positive results may be due to poor quality sampling, preparation, bad cell fixation, maldistribution of cells, and errors in detection and interpretation.

Annually 50 million tests are performed in the U.S. with findings of nearly 1.2 million cases of low grade dysplasia (CIN1), 300,000 cases of high grade dysplasia (CIN2/3) and 10,000 cases of cervical cancer.

Liquid based cytology involve rinsing the sample tool into a vial of liquid to produce a suspension of cells from which a monolayer of cells on a slide is prepared.

Liquid based cytology testing achieved by collecting cervical cells by utilizing traditional sampling device and rinsing it into a vial with a preservation solution with only a portion of the specimen utilized for analysis.

Liquid based cytology can be read more quickly and can be used to test for HPV DNA testing.

Some studies suggest liquid based cytology more sensitive than conventional studies and have a higher proportion of slides that are adequate for assessment, but this has not been confirmed in many other analyses.

Despite many studies there is no superiority for Pap smears compared to liquid based cytology for detecting high-grade lesions (Davey E).

Pap smear’s sensitivity is poor, approximately 50 to 60%, but the frequency of repetition makes it likely that an abnormality missed would be found and subsequent exams.

A single Pap test is limited sensitivity for the detection of cervical cancer and it’s immediate precursors.

To compensate for it’s limited sensitivity repeat screening at short intervals and a low cytologic threshold for additional follow-up is required.

Expenditures in the US total $6 billion annually more than 50 million screening tests.

Tests that are satisfactory but limited by lack of endocervical cells, obscured by blood or inflammation are generally followed up in a year.

Findings of atypical squamous cells of undetermined significance (ASCUS) or low-grade squamous intraepithelial lesion (LSIL) whose initial evaluation have no dysplasia should be rescreened at 6 and 12 months for LSIL or at 12 months for ASCUS, followed by screening every year until 5 years from the last abnormal result.

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