How do you collect endocervical cells during a Pap (Papanicolau) smear?

How to Collect Endocervical Cells During a Pap Smear

Use an endocervical brush inserted until the bristles closest to the handle are approximately even with the external cervical os, then rotate exactly 180 degrees (one-half turn) in the endocervical canal—this technique provides the lowest false-negative rate and ensures adequate sampling of the transformation zone. 1, 2

Optimal Collection Method

Two-Device Technique (Preferred for Non-Pregnant Patients)

The combination of an extended-tip spatula followed by an endocervical brush provides the most thorough sampling with the lowest false-negative rate compared to any other collection method. 1, 2, 3

Step 1: Ectocervix and Transformation Zone Sampling

• Use an extended-tip spatula (plastic preferred over wooden) to perform circumferential sampling by rotating 360° around the cervical os 2, 3
• The extended tip should contact the transformation zone adjacent to the external os during the entire rotation 2
• Plastic spatulas perform better than wooden ones, especially for liquid-based systems, because cells wash off more readily 1

Step 2: Endocervical Canal Sampling

• Insert the endocervical brush until the bristles most proximal to the handle are approximately even with the apparent external cervical os 1, 2
• Rotate the brush exactly 180 degrees (one-half turn) in the canal—no more, no less 1, 2
• Additional rotation beyond 180 degrees does not improve sampling and causes bleeding 1, 2
• The endocervical brush collects significantly more diagnostic cellular material than swabs, particularly in patients with prior cervical treatment (cryotherapy, laser ablation, conization) 1, 2

Single-Device Alternative: Cervical Broom

Cervical broom instruments can simultaneously sample the ectocervix, transformation zone, and endocervical areas and are fairly comparable to the spatula/brush combination. 1

• Insert the long central bristles into the endocervical os while pressing the broom against the cervix so outer bristles bend 1
• Rotate in one direction for five complete rotations (do not reverse direction, as this causes cell loss) 1
• The broom may be used in pregnant women 1

Important caveat: Research evidence shows the broom alone performs poorly compared to the spatula/brush combination, with significantly higher rates of absent endocervical cells (24% vs 10%) and inferior quality indicators. 4, 5 The cytobrush/spatula combination is superior. 4, 6, 7

Special Populations

Pregnant Women

• Avoid the endocervical brush according to manufacturer recommendations due to theoretical risk of amniotic sac perforation, though considerable clinical experience exists with no apparent complications 1
• Use the cervical broom as the preferred alternative 1, 2
• If using a two-device method, combine an extended-tip spatula with a moistened cotton swab (though swabs are less sensitive than brushes) 1
• The Centers for Disease Control and Prevention recommends using a swab and Ayre's spatula for pregnant women 2

Postmenopausal and Older Women

• May have atrophic vagina, stenotic cervical os, and inaccessible squamocolumnar junction 2
• Use gentle scraping with wooden or plastic spatula in circular fashion 2
• Follow with gentle insertion and rotation of endocervical brush 2
• The cytobrush is particularly effective in postmenopausal women with stenotic cervical os, obtaining endocervical cells in 82.4% of stenotic cases versus 0% with cotton swabs 6

Critical Pitfalls to Avoid

What NOT to Do

• Never use cotton swabs for endocervical sampling in non-pregnant patients—they are significantly less sensitive than endocervical brushes 1, 2
• Never rotate the endocervical brush more than 180 degrees, as this causes bleeding without improving cellular yield 1, 2
• Never skip endocervical sampling—at least one-third of false-negative cytology results are due to sampling issues where abnormal cells were never collected 1, 2
• Do not use the broom alone if quality indicators are important, as it is associated with absent endocervical cells (OR=3.12), limited/unsatisfactory results (OR=1.68), and obscuring inflammation (OR=2.01) 4

Quality Assurance

• Verify that the sample contains endocervical cells or immature squamous metaplastic cells to confirm transformation zone sampling 2
• For conventional smears, immediately fix the specimen with spray fixative or 95% ethanol to prevent cellular desiccation 1, 2
• The presence of infectious agents contributes to absence of endocervical cells (OR=3.09), so carefully remove mucopurulent discharge with a saline-soaked cotton swab before collection 2, 4

Pre-Collection Patient Instructions

• Avoid douching for 48 hours prior to the test 1
• Refrain from intercourse for 48 hours prior to the test 1
• Do not use tampons, birth control foams, jellies, or other vaginal creams/medications for 48 hours prior 1
• Schedule to avoid heavy menstrual flow when possible, though do not defer if abnormal bleeding is present 1