HISTORY
Colposcopy has only recently approached its proper place as an important ancillary aid in the practice of gynecology. Despite its late rebirth and popularization, colposcopy has been recognized as a valuable clinical tool abroad for nearly half a century, since shortly after it was first introduced by Hinselmann in 1925.
Colposcopy cannot be considered as a substitute for cytology. It neither competes with nor duplicates cytology but it can and does serve s most critical function in complementing the use of cytology, serving to help study those patients designated by the cytologic screening process as potential at risk, and focusing upon those specific sites warranting biopsy for histologic examination. Indeed, colposcopy stands between population screening and definitive tissue diagnosis.
The cervix and the vagina first became accessible for direct inspection as a result of the invention of the vagina speculum by Recamier in 1818. As a consequence, investigators were able to turn their attention to elucidating the natural history of cervical cancer. By the return of the century, gynecologist shifted their focus of interest from the gross and histologic appearance of advanced disease to the less well defined subject of preclinical carcinoma of the cervix.
Hinselmann in 1925 made a most significant contribution in this regard. He conjectured that the primary focus of cervical cancer may be a minute ulceration or nodule which could be appreciated only with low power magnification from high intensity illumination. He devised the colposcope for inspection of the cervix with sharply focused light and binocular optical magnification, thus pioneering a new field of clinical investigation, colposcopy. Hinselmann’s method of cervical evaluation was widely accepted and enthusiastically promoted throughout Europe.
Colposcopy became a part of every routine gynecologic examination and was utilized as the primary method of cervical cancer screening and detection. The meticulous examination of thousands of patients with the colposcope enabled Hinselmann to define many benign changes on the cervix. With the aid of directed biopsy, he was able to correlate atypical changes with early cancerous or precancerous lesions. He could not find the minute foci of ulceration or nodularity he expected, instead that the colposcope disclosed a variety of epithelial changes corresponding to different benign and malignant histologic patterns. His observation served as the foundation upon which our present day concepts of origin of cervical cancer were built. Cancer begins not in a focus of static tissue but within a sheet of dynamically changing epithelium.
Colposcopy was not widely used by gynecologist in the English speaking countries, with the exception of Australia. Efforts to introduce the technique in the United States began around 1930, but were largely unsuccessful. The delay in its adoption may be attributed to the fact that all the reports of the initial work were published in German. Terminology was based on the visual impressions, such as ground substance and could not be clearly related to the histology or pathophysiology of tumor growth and development. It was not until 1960 that the English reports first placed colposcopy on a logical scientific terminology. Acceptance of colposcopy into American gynecologic practice was also impeded by the introduction in the 1940s of the Papanicolaou smear for diagnostic exfoliative cytology in screening for carcinoma or dysplasia of the cervix.
Cytology and colposcopy were initially construed as competitive rather than as complementary techniques. For detection of cervical cancer, colposcopy proved to be somewhat less reliable than cytology. Moreover, cytology was much more economical, less time consuming, and more easily adapted to mass screening programs. Proper training and special instruments imported from abroad were needed for colposcopy. Additionally, it was difficult to describe complicated visual patterns adequately. Findings were first recorded by hand drawings.
The virtues of combing cytology and colposcopy for cervical cancer detection were first recognized by Navratil and Limbergin 1958. In a series of patients with preclinical cervical carcinoma who were examined simultaneously by colposcopy and cytology, Navratil reported detection by cytology or colposcopy alone approximately 85 percent of cases. Each method compensated for the deficiencies of the other. Current investigations now support a major role for colposcopy in the vaginal examination of women exposed diethylstilbestrol in utero. In addition, colposcopy has been used in evaluating vulvar disease. Colposcopy, especially during the past few years, has come to enjoy growing interest in the United States. This interest has been manifested by the development of teaching aids, instructional and photographic techniques, and American made equipment.
Many gynecologists have acquired a thorough understanding of the technique and practice of colposcopy. The concept of colposcopy depends primarily on the appreciation of visual image, illustrations presented in color to provide accurate and comprehensible representations of clinical material. Colposcopy is still a subject of considerable debate. It has its greatest applications first in the practical evaluation and precise diagnosis of lesions of the cervix, vagina, and vulva, and second in investigational research directed at furthering our understanding of the etiology and pathogenesis of benign and malignant disease in these organs.
Colposcopy is a clinical tool. It is not a difficult procedure. It is easily taught and readily learned, but it should be emphasized that, without proper training, serious mistakes can be made and subtle benefits may never be realized. The colposcope serves to evaluate subtle changes in the surface pattern and terminal vascular network of pelvic tissues. In order to provide the required topographic orientation, any colposcope must include the essential components of magnification, high intensity illumination and stereoscopic viewing.
Photographic recording is desirable although not essential. All colposcopes consist of a stereoscopic binocular microscope with low magnification, usually 10x to 40x. The instrument is equipped with a centered illuminating device which may be mounted in a variety of ways. The light source most often is an incandescent lamp with a rheostat to alter the light intensity. A remote tungsten halogen lamp may also serve this purpose, with its illumination adjusted by a potentiometer and brought to the instrument through a fiberoptic cable. Fiber optic lighting tends to be cooler for both the patient and the colposcopist.
INSTRUMENTATION
The colposcope may be placed on an adjustable stand with a transformer in the base, affixed to the side of an examining table to be swung out, or even attached to the ceiling to be pulled down and centered for the examination of the patients. There are many colposcopes commercially available.
By virtue of their optics, colposcopes fall into two general categories, those containing multiple objectives built into a single optical unit with several fixed magnification and those exhibiting a single objective with fixed magnification. In the fixed magnification focus instruments, the magnification can be altered only by changing the eye pieces. These may be obtained in magnifications varying from 5x to 20x. The optics supplied by different manufacturers can be tailored to the type of work required. The optics influence the working distance between the instrument and the field of examination. The best focal length for a working coloscope is between 200 and 250 mm.
Colposcopes are generally fitted with lenses to provide focal lengths within this range. With a working distance of 200 to 250 mm between the objective lens and the field of examination, the colposcope does not enter the vagina. Punch biopsies, scrapings, and treatments can be carried out under the visual guidance provided by the colposcope. One may find some difficulty and awkwardness at this focal length if one uses biopsy instruments that are longer than 20 to 25 cm. Consequently, instruments such as curettes, endocervical specula, and biopsy forceps should, where possible, be limited to the shorter 15 cm length rather than the 25 cm length in common use. A focal length of 300 mm is more appropriate when long instruments are being used. A short focal length of 100 to 200 mm is often valuable for obtaining photographic records for teaching or research purpose. A separate handle is provided on all instruments for free movement of the focusing element. Care should be taken to align the colposcope so that the light beam strikes the observed tissue at the right angles. With a focal length of 200 to 250 mm and 10x magnification, the diameter of a visualized field ranges in different colposcopes from 20 to 23 mm. this width of with adjacent normal tissue. It is important to keep in mind that the lengthening the focal length at any given magnification will increase the diameter of the exposed field.
The binocular eyepieces of all instruments may have independent focusing elements and are adjustable for individual intraocular distance. They may be fitted with the special rubber cups for eyeglass wearers. The angle of the eyepieces, relative to the long axis of the instrument, is also variable and should be modified for comfort and ease of viewing. In many colposcopes, a built in micrometer permits one to measure the size of involved areas. Most instruments are provided with a green filter for purposes of interposition between the light source and the area being viewed. The green filter absorbs red from the color spectrum, permitting blood vessels to stand out in detail as black objects. Since it increases contrast and accentuates vascular morphology, the green filter is a mandatory accessory. The colposcope is comprised of a modified operating microscope positioned on a system of pivoting arms, mounted on heavy mobile base. Construction allows for universal movement and easy manipulation. The optical head which contains a 6 volt, 30 watt lamp, provides high intensity illumination along the optical pathway. By means of three way switch, the voltage can be increased to brighten the illumination and spotlight any particular area.
The colposcope provides multiple magnifications. The magnification is changed simply by turning a knob with varied settings without a need of refocusing. It is important to recognize the number of the setting does not represent the degree of magnification. At any given setting, magnification is altered by the objective lens and the strength of the oculars. For routine examination, magnification of 10x to 16x is quite satisfactory. When the examination of the entire vagina is necessary, as in vaginal adenosis, the lower powers of 5x to 10x offer the advantage of ease of rapid screening. For detailed inspection of the vascular pattern, the magnification should not be less than 13.5x. Magnification of 20x to 40x may be needed at times for detailed evaluation of abnormal vasculature. However, the benefits of enhanced magnification tend to be outweighed by a decrease in the field of vision, decrease in depth of focus, and loss of architectural orientation.
A photographic unit with a separate optical pathway may be attached to the optical head of the colposcope. The photographic element is focused with plane of the viewing optics. In general, the colposcope is most useful for hospital based practice and for individuals engaged in investigative research.
Colposcopy is an adjunctive diagnostic tool. It serves as a companion to the acknowledged laboratory aids of cytology and histopathology for purposes of tissue analysis. Colposcopy is used for selecting the sites of abnormal epithelium for biopsy in patients with abnormal papanicolaou smears. It is helpful in defining tumor extension and for evaluating benign lesions. It has proved to be valuable to for examining and following diethylstilbestrol exposed offspring.
Colposcopy is a relatively simple procedure. It requires familiarity with only a few pieces of equipment. It involves a systematic approach to inspecting tissue, facility in obtaining biopsy specimens, and precise recording of data.
Good colposcopic technique demands correct positioning of patient and instrument for the examination. The patients must assume the dorsal lithotomy position. She will need to maintain this position for a variable length of time, frequently for as long as 30 minutes when biopsies are taken. The examination table should offer both maximal patient comfort and ease of inspection. Tables equipped with an automatic foot control for adjusting height are often helpful. Special knee and calf support for the patient are also useful. However, the usual stationary gynecologic tables with conventional stirrups are entirely acceptable for colposcopic examination. Such tables may need to be elevated as much as two inches on wooden block in order to perform colposcopic examinations with out neck or back strain.
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