Pap smear

Keywords: Cytology cervical, Cytology gynae, Cervical cytology, Cytology pap smear, Pap, Cervical cytology - conventional sample

Specimen:

Obtained from cervical transition zone. If possible cervical transition zone should be well visualised before sampling. 

Vaginal vault specimens taken following hysterectomy with a history of dysplasia or malignancy. 

Choice of sampling device varies. Alternatives include wooden or plastic spatula, cervical or brush. 

Brush samples may be indicated in peri or postmenopausal women or those with a previous history of glandular abnormality. 

Rapid fixation of specimen is imperative, using either spray cytofixative or immersion in 95% ethanol.

Application:

As part of organised cervical screening programmes, women with no symptoms or history suggestive of cervical disease are screened every two years (Australia) or three years (New Zealand). 

Age of commencement and cessation of screening vary between different organised programmes. 

Women who have never had coitus do not need routine cervical smears. 

Cervical cytology also recommended in the investigation of abnormal vaginal bleeding, especially intermenstrual bleeding or postcoital bleeding. 

Cervical cytology is an insensitive diagnostic test for the diagnosis of cervical malignancy, and women with a significant history or abnormal cervical findings should be referred for further assessment regardless of cervical cytology results.

Interpretation:

Cytology can detect and define squamous and glandular pre-malignancy (squamous intraepithelial lesion, adenocarcinoma in-situ). 

Aim of organised cervical screening programmes is to detect high grade SIL and subsequently reduce the incidence of invasive cervical carcinoma. 

Cervical cytology may also detect changes of invasive squamous carcinoma, invasive endocervical/endometrial adenocarcinoma. 

Specific infections can also be identified on a smear:  Candida, Trichomonas vaginalis, HSV and HPV, and changes of bacterial vaginosis. 

The test is insensitive for the diagnosis of Chlamydia trachomatis infection.

Reference:

Gray W and Kocjan G eds. Diagnostic Cytopathology.  3rd ed. 2010. Churchill Livingstone.

Solomon D and Nayer R. The Bethesda system for reporting cervical cytology. 2nd Ed. 2004. Springer.