The Colposcope |
Multimedia Accessories |
Computerized Colposcopy |
Chemical Agents |
Clinic Needs |
The purpose of colposcopy is the examination of the uterine cervix and lower genital tract epithelium under magnification, identification of potentially dysplastic or cancerous areas, and performance of directed biopsies of abnormal areas to provide a histological diagnosis. Dr. Hans Hinselmann performed the first colposcopic examination by mounting lenses on a pile of books and placing an ordinary lamp above his head. The first true colposcope he developed was a fixed binocular instrument that was mounted on a tripod and equipped with a light source, with a mirror to direct the light. Since that time, a wide variety of advances have been made that improve the functioning and capabilities of the colposcope.
THE MODERN COLPOSCOPE
A colposcope is typically defined as a stereoscopic binocular field microscope with a long focal length and powerful light source.
Two standard colposcope base configurations. Left is an articulated swing arm on a rolling base. Right is a column on a tilting base. A third configuration, the boom-style scope is not shown.
Video colposcopes and optical colposcopes with video feed allow patient and student teaching and facilitate digital image capture. Today, colposcopes permit magnification between x2 and x40, although most routine colposcopic work can be accomplished at a x10 to x15 magnification. Some scopes have a single fixed magnification level. Others have a series of par-focal lenses or a smooth zoom capability that allows for easy adjustment of the magnification via knob or rotor.
Typical multi-magnification colposcope head showing (left to right) the light source, magnification adjustment knob, beam splitter with CCD camera attached, and adjustable eyepieces.
Lower magnification yields a wider view and a greater depth of field for observation. Higher magnification can reveal small features such as abnormal blood vessel patterns and other finer details. As the magnification level increases, the field of view and illumination levels usually decrease.
Interchangeable eyepieces with various levels of magnification are available for most colposcopes. Changing the magnification of the eyepieces alters the magnification levels achieved by the scope. Some eyepieces can be individually adjusted to compensate for variance in individual user's vision. A diopter scale on the side of the eyepiece can identify these.
Eyepieces can be adjusted in a manner similar to microscopes to adjust to each colposcopist's interpupillary distance. Eyepiece hoods or collars can be extended, or can be folded back or removed if the colposcopist wears glasses during the examination. Changing the power of the objective lenses also alters the magnification and working distance (space between the head of the scope and the focal point) of the scope. The usual working distance (focal length) of a colposcope is 30cm. The shorter the focal length, the closer the head of the scope must be to the introitus for clear focus, making it harder to use instruments while viewing through the scope. This also makes it more difficult to work in the vagina with the scope in place. Longer focal lengths may be uncomfortable for colposcopists with shorter arms.
Grossly moving the head of the scope forward or backward coarsely focuses most standard scopes. This can be accomplished by physically lifting and moving the scope, rocking or tilting the scope on a stationary base, rolling it on casters, or pivoting the supporting arm. Most scopes also have a fine focus handle that is attached to a machine screw under the mounting bracket for the colposcope head. Applying pressure to this handle can be used to subtly control the alignment of the scope, and twisting it produces very gradual forward or backward movements of the head for exquisite fine focus control.
A flexible articulating swivel arm or overhead boom type colposcope can be mounted on a stable base (with or without wheels), the wall, or an examination table. A column- or stick-mounted scope can easily be moved from place to place. A good scope should be easily adjustable in both vertical and horizontal directions. A weighted or wide colposcope base prevents inadvertent tipping of the scope and damage to the head or to the optics. Most colposcopes are mounted on wheels, but platform/universal joint bases also are available. The choice of mounting system depends on examination room space requirements, need for mobility, and the colposcopist's preference.
A colposcope usually has a powerful light source, with a rheostat to adjust the level of illumination. Spare light bulbs should be easily accessible since they may have to be changed during a procedure. Bulbs can be halogen, xenon, tungsten, or incandescent. Halogen bulbs produce a strong white light and are often preferred by colposcopists. Some colposcopes have bulbs mounted in the head of the scope, while others are mounted elsewhere and the light is delivered via a fiberoptic cable to the head of the colposcope. Scopes with fiberoptic cables can utilize hotter brighter bulbs, but the cables can be damaged if twisted or bent, producing less overall illumination. The colposcope should be equipped with a green or blue filter (red-free filter). These filters remove red light, thereby enhancing vascular detail by making the blood vessels appear dark.
Commonly available colposcope manufacturers and their contact information and web addresses are shown in Table 1. There are numerous options available for many of the scopes, and the prices are often subject to discounts. ASCCP does not endorse or recommend either specific colposcopes or manufacturers. Scopes are warranted for variable lengths of time.
When the colposcope was first developed, the colposcopist would visualize the cervix and then make a drawing of normal and abnormal findings in the patient's chart. The system for making and labeling drawings has become more standardized since that time, but making a drawing of colposcopic findings in the medical record remains the standard of care for documenting the colposcopic examination. Indeed, some medical-legal experts have expressed an opinion that routine colpophotographs can increase legal risk because an "expert" can always be hired who can find something wrong in almost any photograph.
However, with the advent of better optics and charged-coupled device (CCD) cameras, more options are now available to the colposcopist for documentation and education. Photographic and digital video-printers can produce permanent records of the exact pathology found. Recently, computers have been added to the system to allow fully computerized medical records, complete with digital photographs and the capacity for doing telemedicine.
Multimedia accessories can be added to colposcopes through three major mechanisms. The simplest method of attaching a light-sensitive device to a colposcope is to replace an eyepiece ocular with a camera or a device that redirects the light path to a camera or other viewing apparatus. Unfortunately, this sometimes removes this light channel from use for stereoscopic viewing. Another method of adding multimedia accessories is to have an independent optic system supplying a separate optic port that can have a teaching tube, camera, or CCD video or photographic camera attached. Since the multimedia light channel and the viewing channels must have a completely separate set of lenses and objectives, this adds cost, and the accessory port often has only one magnification level regardless of the number of magnification levels of the viewing ports. The most popular method of adding accessory multimedia ports is via the use of a beam splitter. The beam splitter actually splits a light beam in half and sends the image to two separate ports, one to a viewing port and one to an accessory port. The advantage of this arrangement is that both ports present essentially the same image at the same time. This is especially useful in teaching with teaching tubes or video, since the teacher and learner see the same image at the same time. It also provides the patient with the added benefit of the teaching colposcopist's experienced assessment and input during the procedure.
Colpophotographic systems are useful for documentation of treatment results or pathology that may have to be followed serially over time. They produce more detailed records of pathology than hand-drawings and can be useful with documenting and consulting on unusual findings. They also produce permanent images that can be useful in educating patients and colposcopy trainees. Colpophotographs can be retrospectively checked against pathology results to hone the colposcopist's ability to grade lesions.
When using colpophotography, a permanent camera port is desirable so that fewer image opportunities are missed while finding or attaching the camera to the colposcope. Most colposcopes permit the use of a 35mm or Polaroid camera. Some systems make use of high intensity strobe flashes, which allow for higher shutter speeds that decrease the common problem of blurring on the image due to movement of the colposcope or the patient. Some manufacturers also have cameras available with data systems that record vital patient information onto the colpophotographs. Remote hand or foot shutter release switches are useful in decreasing blurring due to inadvertent motion during shutter activation. Digital colpophotography is being introduced. Some colposcopes have an eyepiece replaceable digital camera that can be used as a normal digital camera or may be put into the eyepiece port of a microscope or colposcope. Other colposcopes have an attachment that fits most beam-splitters and allows attachment of certain commercially available digital cameras.
Videocolposcopy systems can be used for the same purposes as colpophotography, with the added advantage of real-time discussion of pathology with patients or trainees. Covisualization can allow the patient to become aware of normally inaccessible anatomy. By allowing visualization and the opportunity to ask questions, patients may feel some control over the procedure, thereby decreasing anxiety. It also provides higher levels of patient satisfaction. In addition, the patient has the added benefit of a teaching colposcopist's experienced assessment and input during the procedure.
This type of system is especially useful in teaching colposcopy, since the teacher and learner see the same image at the same time, allowing the teacher to actively assess and critique the learner's cognitive and tactile skills during the procedure. Teaching heads provide similar teaching capabilities but are less efficient because they require close physical proximity to the scope (which may be uncomfortable to the observer, colposcopist, or patient), produce a less realistic depth of field, and preclude any benefit the patient might derive from seeing the procedure. Due to the inherent limitations of currently available CCD cameras, the image on a video monitor is almost always less sharp than the image viewed through the eyepieces. This is less pronounced with an integrated videocolposcope. With either type of instrument, using a slightly higher magnification usually resolves resolution problems.
With the recent advent of smaller charged coupled device (CCD) cameras (digital cameras) that are connected via cable to video digitizing boards, the camera can now be mounted on the scope without interfering with the colposcopic examination. The electrical signal put out by the CCD video camera can be recorded by standard VHS or Super-VHS recording devices, or captured by a computer. Images can also be printed via a standard or high-resolution video printer. Videotaped colposcopic examinations can be useful as a means for secondary expert screening. The camera's output may also be digitized and transmitted to remote locations so that distant or rural colposcopists can directly consult or be supervised by expert colposcopists at major medical centers via telemedicine or Internet resources.
With the advent of modern CCD cameras attached to digitizing boards, it became possible to create high-resolution digital images of the cervix that could be displayed real-time, or (along with pertinent patient and examination data) stored, printed, or manipulated by a computer. The image captured can be reviewed and recaptured if suboptimal, unlike with colpophotograpy where the photograph is developed at a later date. Areas of interest can be enlarged, enhanced, or measured. Images also can be stored and retrieved for comparison at future visits or for consultation with expert colpscopists. As medicine moves toward more computerization of medical records, computerized colposcopy allows for easier integration into the electronic medical records. Computerized digital image processing may also facilitate a more quantitative method for following dysplastic lesions over time. Studies are being done on computer-assisted colposcopy, which may help improve training and the accuracy of colposcopic impression.
Many computerized colposcopy systems were originally stand-alone systems made for colposcopy, but integrated systems have now been developed.
Visualization of the cervix is one of the most critical technical components of the colposcopy procedure. Numerous vaginal specula are available for this purpose. A medium Grave's speculum is appropriate for most women. Pederson specula have narrow blades for use in virgins (rare in colposcopy) and women with a narrow vaginal diameter. A large metal Grave's speculum may be required for obese women, pregnant women, and women with vaginal wall laxity. Women with an extremely long vagina may require the use of a long Grave's or Pederson speculum. The light source from the colposcope may be used for vaginal speculum insertion. Internally illuminated plastic speculums may also be used but tend to have thinner blades than standard Grave's speculums.
If the patient has extremely lax vaginal walls, lateral vaginal side-wall retractors can be helpful. The use of these instruments require a degree of skill, for if proper perpendicular alignment with the vaginal speculum is not maintained, severe vaginal pinching occurs. Alternatively, a condom, a penrose drain, a latex ultrasound vaginal probe sheath with the end removed, or the cut middle finger or thumb of a latex glove with the end removed can be placed over the speculum blades to gently hold the side-walls back and allow better visualization of the cervix and vaginal fornix.
The purpose of colposcopic biopsy forceps is to take a small but adequate tissue sample of lower genital tract tissue. Many types of biopsy forceps have been developed. The four most common types of forceps used in the United States are the Tischler, Baby Tischler, Eppendorfer, and Kevorkian biopsy forceps. ASCCP does not endorse or recommend specific brands, specific forceps or other sampling instruments.
Tischler cervical biopsy forceps: A. Standard surgical instrument grips, B. "Pistol grip"
Close-up of cervical biopsy forceps jaws and the silhouette of their biopsy: A. Baby Tischler, B. Tischler, C. Kevorkian. Note the Eppendorfer has the same silhouette and jaw as the Tischler except it has no teeth.
The Tischler forceps is probably the most commonly used in the United States. It combines a rounded jaw and stabilizing tooth with scissors-like blades for minimal crushing artifact and pain. The Baby Tischler combines a stabilizing tooth with scissors-like blades, but has a smaller size, producing a smaller biopsy site with less bleeding and pain. This is especially useful in the biopsy of hypervascular pregnant patients. However, these forceps can produce more crushing artifact and can be more prone to producing inadequate biopsies. The Eppendorfer forceps is basically a Tischler without teeth. It produces minimal crushing artifact and pain, and possibly better endocervical and vaginal biopsies, but makes it more difficult to take excessively deep biopsies. The Kevorkian forceps is less commonly used today. It has a square jaw, with a distal row of teeth on the lower jaw designed to fix the cervix for biopsy. However, it frequently prevents a deep biopsy by stripping only the superficial epithelium.
Regardless of the type of forceps used, keeping the instrument sharp is the most important factor in producing good biopsies and reducing the pain perceived by the patient. Autoclave sterilization can prematurely dull biopsy forceps. Less-damaging sterilization methods include soaking in glutaraldehyde, sterilization with gas, or heating in a bead sterilization system.
The endocervical curette is used to obtain a histologic sample (endocervical curettage or ECC) by scraping the endocervical canal. The distal end of the basket is sharp to act as a blade for the curettage. The Kevorkian curette is most commonly used. It can have an open basket, or the bottom of the basket can be closed or partially closed. A newer method of obtaining an endocervical specimen uses a cytobrush in the endocervical canal. The cytobrush is advanced into the canal and rotated. This can produce a specimen that is more sensitive but slightly less specific than the traditional ECC.
To obtain a satisfactory colposcopy, visualization the entire squamo-columnar junction (SCJ) is necessary. When the SCJ or part of a lesion recedes into the endocervical canal, the colposcopist may need to apply pressure near the os with a cotton-tipped applicator in order to open the canal. If this is not adequate for visualization, an endocervical speculum may be necessary.
Kogan endocervical speculum. Blades typically come in 2mm, 4mm (shown here) or 6mm sizes. The blades may be inserted into the cervical os and gently opened to allow better visualization.
The blades of the endocervical speculum are inserted into the canal to gently retract tissue for proper visualization. This procedure is usually not painful unless the os is stretched. Several of these instruments should be made available, since a size should be selected for each patient that is large enough to allow visualization but not so large that it stretches the os. Endocervical speculums come in several sizes, from 2mm for stenotic os to 6mm for large parous os. Some colposcopists remove the thumbscrews or ratchet lock on the endocervical speculums to allow more dynamic and precise control of the instrument.
Visualizing the squamocolumnar junction was formerly used to triage women with CIN to ablative (laser, cryotherapy) or excisional (LEEP, cold cone) treatment. While unsatisfactory visualization of the SCJ still mandates excisional therapy, women with a deep but visible SCJ also may need excisional therapy when available ablational treatments cannot reach far into the endocervical canal.
Several solutions are used during the colposcopic exam. Normal saline is used as a moistening and cleansing solution during colposcopy. It does not alter the cervical epithelium. It is usually obtained in standard stock bottles from hospital suppliers or from drug stores.
Acetic acid (3%-5%) is used as a contrast solution to enhance the detection of cervical neoplasia during the colposcopic examination. It can be obtained from a supermarket as white vinegar or from a medical supply source. It may be slightly diluted to a 3% solution in an attempt to decrease the stinging sensation to the patient, but this also decreases its time of action on the cervix. Most colposcopists use undiluted 5% solutions.
Aqueous Lugol's solution is an iodine-based contrast solution that is mainly used when examining the vagina, but it may also be used in cervical colposcopy. Lugol's solution is less irritating and just as effective when diluted to half-strength by adding an equivalent amount of tap water or saline. Patients always should be asked about a potential iodine allergy before application of Lugol's solution.
Monsel's solution (Ferric subsulfate) is the most common hemostatic agent used after lower genital tract biopsy or excision. It performs best when it has a thick, toothpaste consistency. It can be bought this way or produced by allowing the stock solution to sit exposed to the air in a small open container. This allows evaporation and thickening of the agent, a process that can be enhanced by placing the open container in a warm place, such as on top of a refrigerator. The resulting paste texture can be maintained by keeping the paste in a closed container and by adding small amounts of Monsel's solution whenever the paste becomes excessively thick. Application of silver nitrate sticks and gelatin foam/powder are less commonly used methods of hemostasis.
A height-adjustable stool is strongly recommended to allow proper back posture for the colposcopist. A height and tilt adjustable table also may help the colposcopist maintain a better posture and also assist in difficult examinations. Table stirrups are usually used for the examination. However, obstetric style knee crutches (padded under-the-knee leg supports) may provide more comfort and less leg strain for the patient. Other useful clinic supplies are shown in Table 2 and a typical mayo tray set-up is shown below.
Typical Mayo tray set-up for colposcopy. From left to right: cotton balls, Monsel's solution, saline, vinegar, Lougal's iodine, cotton-tipped applicators, rectal swabs (Texas Q-tips), Ring forceps, vaginal speculum, biopsy forceps, ECC curette, endocervical speculum. Additional possible items not shown include benzocaine solution, side-wall retractors, and cervix brush.
Skin hooks can be used to stabilize tissue or to change the orientation of vaginal epithelium for examination or biopsy. They can cause obscuring bleeding, so should be used sparingly, especially on the cervix. Ring forceps can be used for applying soaked cotton balls to the mucosal surfaces, for removing mucus, and to gently manipulate the cervix. Long-handled scissors, needle driver, and pickups are rarely necessary to stop bleeding from a biopsy site. Although not proven to reduce the pain of biopsy, many colposcopists prefer to use a topical benzocaine solution just prior to biopsy.
Sterilization processes are a basic requirement. Bactericidal solutions such as glutaraldehyde can be used for instrument sterilization. Other possible methods of sterilization include gas sterilization and steam autoclaving.
Table 1. Colposcope Manufacturers and Contact Information
||São Paulo, Brazil
||(55 11) 2872-4742
|MedGyn Products, Inc.
|| Addison, IL
|Seiler Precision Microscopes
||St. Louis, MO
|Wallach Surgical Devices, Inc
||Skaneateles Falls NY
| Carl Zeiss, Inc
|| Dublin, CA
*Note: Not an all-inclusive listing and again, ASCCP does not endorse or recommend any particular piece of equipment or a manufacturer. Please contact Lisa M. DeGrave at firstname.lastname@example.org
for changes or additions
Table 2. Stock Items Used in Colposcopy
|Cotton balls to apply solutions or tamponade a bleeding site
|Telfa pads for histologic specimens
|Absorbable suture on a cutting needle to control bleeding
|Monsel's solution or silver nitrate sticks
|4 by 4 inch gauze pads
|Sanitary napkins (for post procedure)
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- Cox JT. ASCCP practice guidelines: Endocervical curettage. J Lower Genital Tract Disease 1997; 1:251-6.
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- Ferris DG, Harper DM, Callahan B, Robinson T, Litaker MS, Messing M, Mensah L. The efficacy of topical benzocaine gel in providing anesthesia prior to cervical biopsy and endocervical curettage. J Lower Genital Tract Disease 1997; 1:221-7.
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