From the Guidelines
The primary stains used in cervix examination and colposcopy are acetic acid (3-5%) and Lugol's iodine solution, as they help identify abnormal tissue and guide targeted biopsies. When performing a colposcopy, the application of a 3-5% acetic acid solution is a crucial step, as it causes abnormal tissue to appear white (acetowhite) due to the coagulation of cellular proteins, particularly in cells with high nuclear-to-cytoplasmic ratios 1. Some key points to consider when using these stains include:
- Acetic acid is applied first to highlight areas of increased nuclear density and protein content that may indicate dysplasia or cancer
- Lugol's iodine solution is then applied, which stains normal glycogen-rich squamous epithelium dark brown or mahogany, while abnormal tissue lacks glycogen and remains unstained (iodine-negative)
- The differential staining pattern helps identify the transformation zone and abnormal areas requiring biopsy, as described in the 2006 consensus guidelines for the management of women with abnormal cervical cancer screening tests 1. The use of these stains is essential for improving diagnostic accuracy in cervical cancer screening, and their application is a critical component of the colposcopy procedure.
From the Research
Stains Used in Cervix Examination and Colposcopy
The stains used in cervix examination and colposcopy include:
- Acetic acid: applied to the cervix to highlight abnormal areas, with studies suggesting that a concentration of 5% or 8% can be used 2
- Lugol's iodine: used as a contrast agent to help identify precancerous and cancerous lesions, with research indicating that it can improve the sensitivity and specificity of colposcopic examinations 3, 4
Application and Timing of Stains
The application and timing of these stains can vary, with some studies suggesting that:
- Acetic acid should be applied for 1-3 minutes to allow for optimal visualization of abnormal areas 5
- The use of Lugol's iodine as a secondary contrast agent can improve the accuracy of colposcopic examinations 3
Colposcopic Characteristics and Staining
Colposcopic characteristics and staining patterns can help differentiate between high-grade and low-grade squamous intraepithelial lesions, with features such as: