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Cervical cancer screening tests: Visual inspection methods

Cervical cancer screening tests: Visual inspection methods
Literature review current through: Jan 2024.
This topic last updated: Nov 14, 2022.

INTRODUCTION — Visual inspection of the cervix after application of Lugol iodine, the first method used for cervical cancer screening, was introduced in the 1930s by Schiller [1]. However, Schiller's test has poor specificity and was almost entirely replaced with the advent of cervical cytology.

Current cervical cancer screening protocols typically include a combination of cervical cytology and human papillomavirus (HPV) testing. Visual inspection of the cervix has reemerged as a screening tool for low-resource settings, despite its limited specificity, since it is economical and provides immediate results. Visual inspection can be performed with acetic acid (VIA) or Lugol iodine (VILI). These procedures are also referred to as Visual Inspection with Acetic Acid (VIA) or Visual Inspection with Lugol Iodine (VILI).

Techniques for performing visual inspection of the cervix will be reviewed here. The utility of visual inspection methods, strategies for cervical cancer screening, and techniques for other tests are discussed separately. (See "Screening for cervical cancer in resource-limited settings" and "Screening for cervical cancer in resource-rich settings" and "Cervical cancer screening tests: Techniques for cervical cytology and human papillomavirus testing".)

INDICATIONS — Visual inspection is indicated for patients for whom cervical cancer screening is recommended and for whom these methods are the best screening option (ie, patients who do not have access to cervical cytology and/or human papillomavirus [HPV] testing). (See "Screening for cervical cancer in resource-limited settings", section on 'Alternate: Visual inspection methods'.)

CONTRAINDICATIONS — There are no absolute contraindications to visual inspection of the cervix. Visual inspection with acetic acid (VIA), rather than visual inspection with Lugol iodine (VILI), should be performed in patients with an allergy to iodine. Visual inspection can be performed during pregnancy, but cervical biopsies are relatively contraindicated in pregnant patients unless invasive cancer is suspected.

Active cervicitis is treated before visual inspection because inflammation and infection impede accurate assessment of epithelial abnormalities. Although vaginal infections do not interfere with evaluation, treatment before visual inspection may allow the patient to be more comfortable during the examination. (See "Acute cervicitis" and "Vaginitis in adults: Initial evaluation".)

EFFECTIVENESS — Visual inspection with acetic acid (VIA) and visual inspection with Lugol iodine (VILI) have similar efficacy for the detection of cervical intraepithelial neoplasia or cancer. In our experience, VIA allows a more nuanced and detailed examination of the cervix and is preferable to VILI. VIA also allows for some appreciation of the density of the acetowhitening, the contour, as well as vessel changes, albeit without the detail provided by colposcopy. The efficacy of visual inspection methods for cervical cancer screening and comparisons with other methods are discussed in detail separately. (See "Screening for cervical cancer in resource-limited settings", section on 'Alternate: Visual inspection methods'.)

PROCEDURE

Equipment — The following are used for the performance of visual inspection:

Examination table with stirrups or leg rests; if this is not available, the examination can be performed with the patient supine with knees bent and abducted (ie, frog legs position)

Vaginal speculum

Light source that can illuminate the cervix

3 to 5% acetic acid or 4 to 5% Lugol iodine

Large cotton swabs

Sterile pot for acetic acid and Lugol iodine

Sponge holding forceps for application of acetic acid and iodine

Medical waste receptacle

Lugol iodine is a solution of 5 g of iodine and 10 g of potassium iodide in 100 mL distilled water [2].

Inspection — Visual inspection is performed using the naked eye, as follows [3]:

Position the patient in the dorsal lithotomy or frog leg position

Insert a speculum into the vagina and visualize the cervix

Inspect the cervix and note any lesions

Ensure that the entire cervix is visible and that the squamocolumnar junction is visible in its entirety

Apply either acetic acid or Lugol iodine using a cotton swab, wait for one minute

Inspect the cervix again and note any lesions or color changes

Document the findings

When using acetic acid, a positive test is characterized by opaque, dense, well-defined acetowhite areas that touch the squamocolumnar junction or are close to the external os, or by the presence of a cervical lesion that turns acetowhite (picture 1 and picture 2) [2,4]. The absence of color change is a negative test.

Acetic acid dehydrates cells so that squamous cells with relatively large or dense nuclei (eg, metaplastic cells, dysplastic cells, cells infected with human papillomavirus [HPV]) reflect light and therefore appear white. Blood vessels and columnar cells are not affected by acetic acid, but become easier to visualize against the white background. It is important to note that not all acetowhite lesions are diagnostic of cervical precancer or cervical cancer. The differential diagnosis of an acetowhite lesion includes changes associated with HPV infection, leukoplakia (caused by chronic irritation), or squamous metaplasia. (See "Colposcopy".)

When using Lugol iodine, a positive test consists of pale yellow areas against a darker background; uniform uptake of stain is a negative test. Glycogen-containing cells will take up iodine and become dark brown. Non-glycogenated cells, such as normal columnar or glandular cells, high-grade lesions, and many low-grade lesions, will not take up iodine and remain light yellow (picture 3).

Complications — There are no known complications of visual inspection of the cervix. Patients may report a transient sensation of vaginal burning with application of acetic acid. If biopsy is performed, infection or excessive bleeding occurs rarely. (See "Colposcopy", section on 'Complications'.)

MODIFICATIONS OR ALTERNATIVE TECHNIQUES

Magnification — Visual inspection with acetic acid (VIA) can be combined with examination of the cervix with a 2 to 4x magnifying lens, in contrast to the 7.5 to 30x magnification used for colposcopy [4,5]. However, magnification does not appear to improve the performance of VIA. (See "Screening for cervical cancer in resource-limited settings", section on 'Other'.)

Speculoscopy — Speculoscopy is similar to VIA, with the addition of a blue-white chemiluminescent light source attached to the upper speculum blade. The examiner can assess the cervix for acetowhite lesions directly or with the use of limited magnification (4 to 6x).

Cervicography — Cervicography refers to standardized photography of the cervix after the application of acetic acid. In its original design it used a specially adapted camera that could take a photograph very rapidly. The 35 mm magnified images can then be interpreted by qualified evaluators anywhere in the world, and the patient triaged accordingly. In some clinical settings, cervicography is considered to be an adjunct to cervical cytology rather than a primary screening method. Some clinics use standardized digital cameras, or even cell phone cameras, to photograph the cervix, which allows for review of the images at a later time or by a remote expert [6]. This is discussed in more detail separately. (See "Screening for cervical cancer in resource-limited settings", section on 'Alternate: Visual inspection methods'.)

FOLLOW-UP OF ABNORMAL FINDINGS — Areas with abnormalities and gross cervical lesions should be biopsied, if possible. In protocols in which treatment immediately follows screening ("screen and treat"), biopsy is important to identify or exclude patients with invasive cancer. Features suggestive of cervical cancer include a lesion that involves three or four quadrants of the transformation zone, extends into the cervical canal or vaginal walls, and bleeds easily on contact. Other features include raised irregular lesions and often a yellowish discoloration.

Detection of cervical intraepithelial neoplasia is enhanced by obtaining multiple biopsies from the most abnormal appearing area and/or from more than one abnormal appearing area. Biopsies should be taken from inferior to superior to avoid bleeding over the target sites.

Each specimen is individually labeled according to its location on the cervix (as if taken from the face of a clock) and placed in a separate, labeled container containing a permanent fixative, such as 10% formalin.

Biopsy of a large cervical mass presumed to be a cervical cancer may lead to significant bleeding. In such patients, it may be preferable to defer biopsy until a full examination under anesthesia can be performed for staging and where there are facilities to manage excessive bleeding. (See "Invasive cervical cancer: Staging and evaluation of lymph nodes".)

Local anesthesia is not routinely used for biopsies of the cervix and upper vagina, since injection of the anesthetic is probably as painful as the biopsy. Distraction techniques (eg, asking the patient to cough at the time of biopsy) are as effective as local anesthetic injection and require less time. Topical and oral analgesics are ineffective. (See "Colposcopy", section on 'Biopsies'.)

Because of an increased risk of bleeding, biopsies are relatively contraindicated in patients on anticoagulants, who have a known bleeding disorder, or who are pregnant. If a biopsy is necessary in such patients, appropriate steps should be taken to minimize bleeding and to treat heavy bleeding if it occurs.

In settings where biopsy and treatment of lesions are not possible, patients with abnormal findings should be referred to an appropriate clinician for further evaluation and treatment.

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Cervical cancer screening, prevention, and management".)

SUMMARY AND RECOMMENDATIONS

Visual inspection of the cervix after application of acetic acid (VIA) or Lugol iodine (VILI) is used for cervical cancer screening in patients who do not have access to cervical cytology or human papillomavirus testing. (See 'Indications' above.)

There are no absolute contraindications to visual inspection of the cervix. VIA, rather than VILI, should be performed in patients with a known allergy to iodine. This examination can be performed during pregnancy; cervical biopsies are relatively contraindicated. (See 'Contraindications' above.)

For patients undergoing cervical cancer screening with visual inspection of the cervix, we suggest VIA rather than VILI (Grade 2C). (See 'Effectiveness' above and "Screening for cervical cancer in resource-limited settings", section on 'Alternate: Visual inspection methods'.)

Visual inspection of the cervix is performed using the naked eye after application of acetic acid or Lugol iodine. With acetic acid, a positive test is characterized by opaque, dense, well-defined acetowhite areas touching the squamocolumnar junction or close to the external os, or presence of a cervical lesion that turns acetowhite (picture 1 and picture 2). Using Lugol iodine, a positive test consists of pale yellow areas against a darker background. (See 'Procedure' above.)

Areas with abnormalities and gross cervical lesions should be biopsied. In protocols in which treatment immediately follows screening ("screen and treat"), biopsy is important to identify patients with invasive cancer who require further treatment. (See 'Follow-up of abnormal findings' above.)

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