Colposcopy of the Vagina and VAIN

Introduction

1. Comprises about 4% of intraepithelial neoplasias.
2. Occurs in between 0.9 and 6.8% of cases following hysterectomies -- with a higher incidence following surgery and radiation therapy for pre-malignant and malignant lesions of the cervix.
3. 28% of VAIN cases have been reported to occur after hysterectomy for benign disease.
4. Appropriate colposcopic assessment is necessary for diagnosis.

1. It is approximately 3 inches long and lies behind the bladder and urethra and in front of the rectum.
2. It is a curved, flattened tube which increases in diameter posteriorly.
3. It extends from the hymenal ring to the vaginal fornices.
4. The uterine cervix projects downward and backward into the upper part of the vagina, forming 4 anatomical topographic recesses called fornices -- posterior fornix, anterior fornix, and 2 lateral fornices.
5. The anatomical wall of the vagina consists of a fibrous outer coat, a muscular coat, and an internal mucous lining, which is covered by stratified squamous epithelium in continuation of the stratified squamous epithelium of the outer part of the cervix.

1. In the sexually mature woman, the epithelial squamous cells form four distinct histologic zones:

a. Basal cells- - a single layer of cuboidal cells attached to the basement membrane. These cells are firmly attached to the basement membrane and do not exfoliate, so are absent from vaginal smears. It is from these cells that regeneration of the epithelium is maintained. They are the least mature cells.
b. Parabasal cells -- a zone of several rows of polyhedral cells superficial to the basal layer. These cells may be seen in Pap smears. When these cells exfoliate they lose their intercellular bridges and appear round or oval.
c. Intermediate layer -- several rows of slightly larger, flatter cells above the parabasal cellular layer. When these cells exfoliate, they appear larger and less rounded than the parabasal cells. The lower most parabasal cells stain bluish-green and those near the surface take up the eosinophilic stain when examined cytologically.
d. Superficial zone -- several layers of large, flat cells with dark pyknotic nuclei. In Pap smears, these cells are large and polyhedral with a clear transparent cytoplasm. Under certain pathological conditions these cells may lose their nuclei and become keratinized, and take up an orange color on Papanicolaou stain. The superficial squamous cells in this zone usually stain pink unless the pH of the vagina is abnormal.

2. The composition of the epithelium, especially its thickness, is dependent upon estrogen. It is recognized as being thin and atrophic before puberty and after menopause. The epithelium is thickest during the reproductive life.

Colposcopic Evaluation of the Vagina

• The procedure should be discussed with the patient and informed consent obtained.  Use only water or saline as lubricants since others may interfere with good visualization and staining of the vaginal mucosa.
• Carefully insert the speculum to prevent trauma to the mucosa. This is particularly important in nonestrogenized and post-irradiation patients.
• Note and record gross lesions such as erythema and hyperkeratosis.
• A Pap smear may be taken if desired.
• Colposcopic Procedures:
• Any mucus in the vagina can be gently removed with swabs moistened in normal saline.
• A blue or green filter may be employed to identify any vascular patterns present, although they are rare in VAIN.
• Inspect the entire vagina under low magnification before and after the application of 3% - 5% acetic acid and then iodine (Schiller's solution or Lugol's iodine) to the entire vagina.
• Biopsies are taken from the area(s) exhibiting the most severe colposcopic patterns and from iodine-positive areas (that is, those failing to take up the iodine stain). Vaginal hooks may be necessary to gently pull part of the side-wall forward to allow for easier biopsy.
• Monsel's solution is applied with a cotton-tipped applicator to the biopsy site(s) to control any bleeding if necessary.
• A bimanual pelvic examination is performed following the colposcopic examination. Feel the vagina for side-wall lesions.
• Review the colposcopic findings with the patient.

Difficulty of Vaginal Colposcopy

References