How to Perform a Pap Smear
The Pap smear should be obtained using an Ayre spatula or similar collection device to sample the cervical transformation zone, with the specimen immediately spread on a glass slide and fixed in 95% ethyl alcohol, or placed in liquid-based cytology medium.
Patient Preparation and Positioning
- Position the patient in the dorsal lithotomy position with appropriate draping for comfort and privacy 1, 2
- Perform a speculum examination to visualize the cervix adequately before specimen collection 2
- Ensure the patient has not had intercourse, douched, or used vaginal medications for 24-48 hours prior to the test for optimal specimen quality 1
Specimen Collection Technique
Sampling the Cervix
- Use an Ayre spatula to sample the ectocervix by rotating it 360 degrees around the external os to capture cells from the transformation zone 1, 3, 2
- For endocervical sampling, use a cytobrush or endocervical brush inserted into the endocervical canal and rotated 180-360 degrees 2
- The transformation zone (squamocolumnar junction) is the critical area to sample, as this is where most cervical cancers and precancerous lesions arise 1
Specimen Handling
- Immediately spread the collected material evenly across a clean, grease-free glass slide in a single stroke to avoid clumping 1, 3
- Fix the slide immediately by immersing it in 95% ethyl alcohol fixative to prevent air-drying artifact 1, 3, 2
- For liquid-based cytology, rinse the collection device in the provided vial containing preservative solution 4
- Label the slide or vial with patient identification before fixation 2
Quality Assurance
- An adequate sample should contain sufficient squamous cells and endocervical/transformation zone component 2
- Studies show that 6.42% of samples may be inadequate, requiring repeat collection 2
- Ensure proper technique to minimize inadequate specimens that delay diagnosis 2
Clinical Context for Screening
- This technique applies to women aged 21-65 years undergoing routine cervical cancer screening 5, 4
- For women 21-29 years, cytology alone every 3 years is recommended 5, 6, 4
- For women 30-65 years, options include cytology every 3 years, primary HPV testing every 5 years, or co-testing every 5 years 7, 6, 4
Common Pitfalls to Avoid
- Avoid air-drying the specimen before fixation, as this creates artifact that makes interpretation difficult 1, 3
- Do not perform Pap smears during menses, as blood can obscure cellular detail 1
- Ensure adequate sampling of the transformation zone, as sampling only the ectocervix may miss lesions 1, 2
- Do not screen women under 21 years of age, as this leads to more harms than benefits 5, 4