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Sequential Application of Lugol's Iodine Test after Acetic Acid for Detecting Cervical Dysplasia: A Prospective
Günther A Rezniczek1, Samira Ertan1, Sadia Rehman1
1Department of Obstetrics and Gynecology, Marien Hospital Herne, Ruhr-Universität Bochum, 44625 Herne, Germany.
Insights
Lugol's iodine test for cervical lesions shows moderate sensitivity and poor specificity in detecting low-grade/high-grade squamous intraepithelial lesions (LSIL/HSIL). However, it influenced clinical management in 5.3% of cases when used with acetic acid during colposcopy.
Area of Science:
- Gynecology
- Oncology
- Pathology
Background:
- Cervical cancer screening relies on identifying squamous intraepithelial lesions.
- Lugol's iodine staining is a standard colposcopic adjunct for lesion detection.
- Standardized protocols are crucial for evaluating diagnostic test performance.
Purpose of the Study:
- To assess the diagnostic performance of Lugol's iodine test in detecting LSIL/HSIL during colposcopy.
- To evaluate secondary parameters including lesion appearance time, staining intensity, and fading.
- To determine the impact of Lugol's iodine on clinical management decisions.
Main Methods:
- A prospective cohort study involving 320 women undergoing colposcopy.
- Standardized protocol: 5% acetic acid followed by 5% Lugol's iodine.
- Recording of most severe acetowhite lesions (MSAWL) and iodine-negative lesions (MSINL).
- Primary endpoint: sensitivity and specificity of MSINL for LSIL/HSIL detection.
Main Results:
- MSINL demonstrated a sensitivity of 81.4% and specificity of 29.5% for LSIL/HSIL detection.
- Lugol's iodine exclusively identified 96 MSINLs, with 1.9 needed to biopsy for one additional LSIL/HSIL.
- Clinical management was altered in 5.3% of patients based on Lugol's iodine results.
- MSINL appeared instantly (within 10s) and staining intensity correlated with lesion severity.
Conclusions:
- Lugol's iodine test, when used with acetic acid, offers moderate sensitivity but poor specificity for LSIL/HSIL.
- The test can influence clinical management in a small percentage of cases.
- Instantaneous staining and correlation with lesion severity are notable characteristics.
Abstract:
Applying Lugol's iodine solution to the cervix followed by colposcopic assessment is an established standard test to identify low grade/high grade squamous intraepithelial lesions (LSIL/HSIL). Here, we assessed the performance of Lugol's iodine test during colposcopy using a standardized protocol with 5% acetic acid followed by 5% Lugol's iodine solution and recording the most severe acetowhite (MSAWL) and iodine-negative (MSINL) lesions in a prospective cohort of consecutive women referred to our specialized colposcopy unit. The primary study endpoint was the sensitivity/specificity of MSINL for the detection of LSIL/HSIL. Secondary endpoints were the time to first appearance of the MSINL, MSINL staining intensity, and fading of MSINL. Three hundred and twenty women were included. The sensitivity and specificity of MSINL for the detection of LSIL/HSIL was 81.4 (95%-confidence interval (CI) 77.3-85.0)% and 29.5 (24.2-35.5)%, respectively. Ninety-six MSINL were identified exclusively by Lugol's iodine test (no pathology, n = 46; LSIL, n = 29; HSIL, n = 21) (number needed to biopsy to identify one additional LSIL/HSIL = 1.9). In 17/320 (5.3%) patients, the clinical management was changed based on the result of Lugol's iodine test. Video analysis showed an instant appearance of the MSINL within 10 s in 100% of cases. Intensity of MSINL significantly correlated with the presence/absence of LSIL/HSIL (Spearman rank order correlation; p < 0.0001). Fading of iodine-induced staining intensity over time was not observed. Thus, Lugol's iodine showed moderate sensitivity and poor specificity, but changed clinical management in 5% of cases when used in addition to acetic acid.
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