What Does the Bethesda System Mean on a Pap Test?

The Bethesda system is an agreed set of words for Pap test findings. It does not rank a result from 1 to 10. It gives each kind of cell change a fixed name, so that any lab describes the same cells the same way.

That is why a Pap report can look oddly flat. The wording carries the meaning. There is no number to compare against a scale.

Cervical Pap results use The Bethesda System for Reporting Cervical Cytology. The current book is the third edition, built on the 2014 update.

A separate Bethesda system exists for thyroid needle samples. Its third edition came out in 2023 and uses six categories with different names, such as benign and follicular neoplasm.

The two share a name and little else. If a report just says "Bethesda," check which organ it describes.

A cervical report starts with whether the lab could read the sample at all.

An unsatisfactory result means the lab could not judge it. NCI says this happens when there were too few cells, or when the cells were clumped or hidden by blood or mucus. The usual answer is another Pap test in 2 to 4 months.

This is not an abnormal result. It is a blank one.

Most cervical cells on a Pap are squamous, the flat surface cells. NCI describes these findings:

• Normal. Also written as negative for intraepithelial lesion or malignancy.
• ASC-US. Atypical squamous cells of undetermined significance. This is the most common abnormal Pap finding. Some cells look slightly off, and the reason is unclear. An HPV test usually follows.
• LSIL. Low-grade changes, usually caused by an HPV infection.
• ASC-H. Cells that may be a high-grade change, though the lab cannot be sure. Colposcopy usually follows.
• HSIL. Moderately or severely abnormal cells that could become cancer if left alone. Colposcopy usually follows.
• Cancer cells. Very rare in people screened on schedule.

Glandular cells line the canal above the cervix. They are read separately.

Atypical glandular cells, or AGC, can point to a problem higher up in the uterus. NCI says colposcopy is the usual next step. Adenocarcinoma in situ, or AIS, is a precancer in that glandular tissue.

A glandular finding is not simply a worse version of a squamous one. It sends the search somewhere else.

The Bethesda term is only half the picture. NCI notes that follow-up now uses the ASCCP risk-based approach.

That approach weighs your current result together with earlier screening results, any past treatment for cervical cell changes, and your age. Two people can share the word ASC-US and be offered different plans.

Possible next steps include a repeat HPV test or co-test in 1 or 3 years, a colposcopy with biopsy, or treatment.

A Pap looks at loose cells. A biopsy looks at tissue, and it is graded as CIN 1, CIN 2, or CIN 3.

NCI maps them roughly: LSIL on a Pap is generally CIN 1, while HSIL can be CIN 2, CIN 2/3, or CIN 3. The Pap word is a flag. The biopsy word is the finding.

• Was the sample satisfactory for evaluation?
• Which exact term did the lab use?
• What did the HPV test show?
• Which of my past results is affecting this plan?
• Is the next step a repeat test, a colposcopy, or nothing for now?

Call 911 or get emergency care now if vaginal bleeding is soaking through a pad an hour for more than an hour, or if you feel faint, dizzy, or short of breath with it.

Call your care team without waiting for a routine appointment if you have heavier bleeding than usual, bleeding after sex that keeps happening, pelvic pain that is getting worse, or any symptom they told you to report.

Next steps after an abnormal result are covered in Abnormal Pap or HPV Positive: What Now and What Does Positive HPV 16 or 18 Mean. For the test itself, see Cervical Cancer Screening and Biopsy.

• National Cancer Institute — HPV and Pap Test Results: Next Steps after an Abnormal Cervical Cancer Screening Test
• Nayar R, Wilbur DC. The Pap Test and Bethesda 2014. J Low Genit Tract Dis. 2015
• Ali SZ et al. The 2023 Bethesda System for Reporting Thyroid Cytopathology. Thyroid. 2023