From the Guidelines
The material for a Pap smear consists of cells collected from the cervix using a spatula and/or brush, with liquid-based cytology being the preferred method due to its cleaner sample and ability to test for HPV. The most common collection devices include a plastic spatula for the ectocervix (outer portion of the cervix) and a cytobrush for the endocervical canal, as described in the 2021 guidelines for sexually transmitted infections treatment 1. These tools gently scrape or brush the cervical surface to obtain a sample of cells. Once collected, the cells are either spread directly onto a glass slide and fixed with a preservative (conventional method) or placed in a liquid preservative solution (liquid-based cytology).
The advantages of liquid-based cytology over conventional Pap testing are highlighted in a 2014 study on cervical cancer screening, which notes that liquid-based cytology allows for easier reading and the ability to test for HPV using the same sample 1. The 2021 guidelines also support the use of liquid-based cytology, stating that it can be performed at any time during the menstrual cycle and that the presence of a mucopurulent discharge should not postpone cytology testing 1.
Key points to consider when collecting a Pap smear sample include:
- Using a plastic spatula for the ectocervix and a cytobrush for the endocervical canal
- Spreading the cells onto a glass slide and fixing with a preservative (conventional method) or placing in a liquid preservative solution (liquid-based cytology)
- Performing the collection process during a pelvic examination
- Sending the sample to a laboratory for examination under a microscope to detect any abnormal cells
- Considering the use of liquid-based cytology due to its advantages over conventional Pap testing, as supported by the 2021 guidelines 1 and the 2014 study on cervical cancer screening 1.
It is also important to note that the sequence of cytology testing in relation to collection of other endocervical specimens does not influence Pap test results or their interpretation, as stated in the 2021 guidelines 1. Additionally, the use of instruments designed to sample the cervical transformation zone, such as cytobrushes, improves the accuracy of cytology tests, as noted in the same guidelines 1.
From the Research
Material for Pap Smear
The material used for a Pap smear is typically collected from the cervicovaginal epithelium, with the goal of sampling the complete transformation zone (TZ) and the squamocolumnar junction (SCJ) 2. Various sampling devices are available, including the Ayre spatula and the plastic narrow long tip (Szalay) spatula, with the latter providing higher satisfactory smears for Pap tests 3.
Sampling Devices
- Ayre spatula: commonly used for cervical smear collection, but may result in higher rates of inadequate smears 3
- Plastic narrow long tip (Szalay) spatula: provides higher satisfactory smears for Pap tests, with better cellular quality 3
- Cervex brush: designed for liquid-based preparations, ensuring sampling of the complete TZ and SCJ, with pre-fixation of cells in a weak fixative 2
Collection and Preparation
The collection and preparation of Pap smear material require careful attention to detail, including immediate wet fixation of the smear to ensure reliability of cervical cytology for detecting precancerous lesions 2. The use of liquid-based preparations, such as the Cervex brush, can simplify the process and improve the quality of the sample 2.
Alternative Screening Tools
Other screening tools, such as visual inspection with acetic acid (VIA), Lugol's iodine (VILI), cervicography, and HPV testing, have been compared to Pap smear cytology in various studies 4, 5. Additionally, new technologies like the TruScreen optoelectronic device have shown potential as an alternative or adjunct to Pap Smear for cervical cancer screening, with high sensitivity and specificity for detecting cervical abnormality 6.