Colposcopy of the vulva - vulvoscopy - is an important part of gynecological examination. However, it does not provide as many informations about the nature of vulvar lesions as colposcopy of the cervix does. It is due to normal histology of this area, which is covered by a keratinized, stratified squamous epithelium. Multifocal nature of vulvar intraepithelial disease makes the examination more difficult. Nevertheless, colposcopy should be performed in examination of vulvar pathology because of its particular importance in identifying the individual components of the lesions, both for biopsy and treatment purposes.
Anatomically vulva, the term that designates external female genital organs, consists of the mons pubis, the labia majora, the labia minora, the clitoris including frenulum and prepuce, the vestibule (the vestibulum, the introitus), glandular structures that open into the vestibulum and the hymen.
Colposcopically, vulva includes the external urethral orifice, the perineum, the perianal area and the anus.
Embriological origin of these structures differs. The epidermis of the vulvar skin and its appendages are of ectodermal origin. The dermis is derived from mesoderm. Vestibulum is the only structure that origins from the endoderm, like bladder and urethra. Consequently, the histology of these structures is not the same.
Vulvar skin which has ectodermal origin consists of epidermis which is keratinized nonglycogenated stratified squamous epithelium and two layers of dermis (papillary and reticular), that are situated over the underlying fat tissue.
Mons pubis, lateral parts of the labia majora and the perianal area are covered by hair-bearing skin. The hair, the hair follicle, the sebaceous gland, the arrectores pillorum muscle and the apocrine glands form a distinct functional unit- pilosebaceal unit. Eccrine sweat glands are also present.
The inner parts of labia majora, entire labia minora and clitoris are covered by non hair-bearing skin. These areas are richly provided with sebaceous glands which open directly onto the skin.
Vestibulum is covered by non-keratinized squamous epithelium. It contains mucus secreting glands.
In the attempt to colposcopically examine vulva, it is essential to know the histology of vulvar skin since the appearance of the lesion largely depends on the tissue structure of the affected site.
Besides its own special properties of structure, vulvar skin has specific functional features. Physiology of vulva is following the principles of all other parts of female reproductive system. Vulva is responsive to the sex steroids. The alterations that are clinically recognizable in the vulva throughout life and additional cyclic changes occurring during reproductive period are the result of sequential aberrations of ovarian hormone secretion. Significant changes happen during puberty, sexual intercourse, pregnancy, delivery, menopause and postmenopausal period, which alter external appearance and function of vulva. Knowledge about this cyclical activity is important in diagnosis and treatment of vulvar disorders.
It should be remembered that vestibulum, as an endodermal derivate is less sensitive to sex hormones than adjacent structures. This should be aware of in treatment of certain vulvar conditions such as vestibulitis.
Tissue basis of colposcopy of the vulva
The colposcopical image of different vulvar lesions depends on the features of the tissue examined. The most important ones are the thickness of the epithelium and the vascularity of the underlying stroma.
Thickness of the skin affects the opacity. It varies from one person to another and in between different areas of the vulva. Skin of hair-bearing parts is thicker than the skin of other areas of the vulva. This is why histologicaly identical lesions may have different appearance when present on different parts of the vulva.
Vulvar epithelium is predominantly dry. Its prominent surface keratin layer does not provide a clear view of the underlying blood vessels. Pigmentation can also obscure blood vessels. Therefore vascular patterns are less marked and less reliable than in colposcopy of the cervix. Vascular aberrations such as punctations and mosaic patterns do not easily develop on vulvar skin. They are less common and practically can be seen on the non hair-bearing areas only. These are the inner portions of labia minora where keratin layer is thinner and vestibular epitheluim which does not contain keratin layer.
Stromal changes that influence colposcopical appearance are usually due to the increase in vascularity. This increase may be a part of an inflammation, an immune response or the neovascularisation of neoplasia. In these cases color of the skin will become red. The vascularisation may also be decreased or stroma may undergo fibrotic changes which result in whitish coloring of the skin.
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Technique of colposcopy of the vulva
The technique of colposcopy of the vulva does not differ from usual colposcopy examination of the cervix. The patient is examined in lithotomy position. This examination can be unpleasant and even painful for some woman. Therefore it is necessary to perform it gently, but thoroughly.
All parts of the vulva have to be examined: labia majora and minora, vestibule, clitoris, terminal urethra, perineum, perianal regia, and anus till its mucocutaneous junction. It may also be wise to carry out a colposcope examination of the anal canal if patient is tolerant to such examination. This is performed with the aid of a proctoscope. The examination has several stages.
1. Visual examination - inspection
The examination of the vulva should start by visual examination of entire vulvar region. Simple examination usually offers adequate visibility of mons pubis, labia major, the rim of labia minor, perineum and anus. The attempt should be made to clearly visualize the hair-bearing skin. Proper examination requires separation of labia majora and minora and exposition of entire vesitibule to the view.
This part of examination is particularly important because it reveals fields of redness, hyperkeratinization (leukoplakia), pigmentations, ulcerations and atrophia. Genital warts or invasive cancer can be easily recognized. Application of water soluble lubricant, analogue to examination with saline in colposcopy of the cervix, decreases the keratinizing effect to a certain extent and assists in visualization of abnormal vessels.
2. Application of acetic acid
Application of acetic acid is next, very important stage of vulvoscopy. Many otherwise undetected lesions, particularly HPV lesions may present as white areas. The lesions will appear as shiny aceto-white patches with a spiculated or micropapillary surface. Punctation and mosaic do occur on the musocal surface of labia minora, and should be searched for.
Compared to the examination of the cervix, the acetic acid has less prominent effect on the vulva. To make the examination of keratinized skin more efficient, acetic acid should be applied frequently, in large amounts and in more concentrated solution (5%). The application has to be long enough, usually 2-3 minutes, to allow vulvar lesions to show. Useful way to achieve this is to compress gauze swab soaked with acetic acid against the vulva.
Colposcopy should begin using the lowest magnification (6x) to quickly scan the vulva. Later it can be proceeded to higher magnifications, as necessary, to examine for smaller satellite lesions. Keratosis aggravates the normal opacity of vulvar surface. In such cases the magnification afforded under good lightning aids delineation of lesions. Top
3. Collins test
The test that uses the solution of toluidin blue to mark vulvar lesions is known as Collins test. Toluidin blue is nuclear stain that fixes for surface cells nuclei when applied in vivo. All foci of nuclear activity will keep the color and become stained. This may happen not only in neoplasia but also in the presence of ulcerations, lacerations, reparative changes and parakeratosis. Therefore although useful, this test was not considered specific enough. However, it has recently been reported that the toluidine blue test is an inexpensive and reliable method of separating vulvar intraepithelial neoplasia from hyperplastic non-neoplastic epithelial disorders and choosing a biopsy site on the vulva.
Collins test is performed by applying 1% aqueous solution of Toluidin blue to skin carefully cleaned from ointment or powder. The application should take 2 minutes. Afterwards vulvar epithelium is discolored by rinsing with 1% acetic acid. The stain will be entirely washed from normal skin because surface epithelium does not contain nuclei. Any condition which results in the presence of nucleated cells on the skin surface will retain the color which will be visible as fine blue spots that can be identified under colposcopic examination.
4. Biopsy
Vulvoscopy can exactly localize the lesion. It usually can not predict the histological nature of the lesion. Proliferated tissue with abnormal vascular pattern is always suspicious to invasion. However, majority of vulvar lesions does not have specific characteristics. Therefore, the diagnosis of vulvar lesion always requires biopsy.
Biopsy is mandatory in:
Fast growing lesions
Ulcerations
Fields of bleeding
Each suspicious field of any color
Large lesions and multicentric lesions will require multiple biopsies.
Vulvar biopsy is relatively easy to perform using variety of instruments. The procedure may be painful and it is always useful to minimize the discomfort of the patient by applying local anesthesia. The biopsy site can be anesthesied by injecting 1% xylocain (lidocain) or 3% prilocain solution by fine needle, subepithelialy or subdermaly. Apart from anesthetic effect, the injection lifts the skin and the biopsy will be easier. The attempt should be made to get the specimen, at least 5mm thick.
Keyes instrument (Keyes punch forceps) is often used for punch biopsy of the vulva. It will remove the round skin area of desirous diameter. Usually 3-5 mm punch forcepses are chosen. The procedure is performed by firmly pushing the punch into the skin with a rotation action. The depth will depend on the sharpness of the instrument and the pressure applied, as well as of the thickness of epidermis. When the instrument reaches dermis the resistance is decreased. If in this point the further pressure is applied, there is the risk of going too deeply, which can cause severe bleeding. Fine tissue forceps or scissors are necessary to detach the specimen from dermal tissue. The defect that remains after the biopsy can be left to heal spontaneously. The healing finishes in 2 weeks. Monsel's solution (ferric subsulfate) can be very useful to control the bleeding. Only rarely the biopsy defect require suturing.
The more simple method is biopsy of the vulva with cervical biopsy forceps. The bleeding is minimal and can be stopped by simple pressure or application of Monsel solution.
Ulcerative lesions and very thick lesions should be completely excised to rule out focal invasion (excision biopsy). Eliptical excision is made with scalpel and the wound is closed by 2/0 or 3/0 Vicryl sutures.
After the biopsy the specimen should be put on absorbent paper with the dermal side down, facing the epithelial side upwards. 10% formalin is usually used as a fixative. It is very important to orient the specimen properly, to avoid tangentional sections which may cause difficulties in histological interpretation.
5. Documentation of vulvar findings
The colposcopical findings on vulva should be precisely documented. A schematic drawing in the patient's record has sufficed for many years. For this purpose the simplified scheme of vulva which presents labia majora, both sides of labia minora, vestibulum, perineum and anus is sufficient. Exact localization of any finding should be marked in the specially designed diagram.
More objective documentation of colposcopic images may be achieved by photographic camera attached to the colposcope or by extending the colposcope with a video camera, an on-line monitor and video printer.
Recent advances in computer technology using digital color imaging colposcopy system, up to now applied for the examination of the cervix, seem to be promising for objective documentation of vulvar findings, too.
