What is colposcopy?
Colposcopy is a gynecological procedure that illuminates and magnifies the vulva, vaginal walls, and uterine cervix in order to detect and examine abnormalities of these structures. The cervix is the base of the womb (uterus) and leads out to the birth canal (vagina). During colposcopy, special tests [acetic acid wash, use of color filters, and sampling (biopsy) of tissues] can be done. Colposcopy is not to be confused with culdoscopy, which is the insertion of an instrument through the wall of the vagina in order to view the pelvic area behind the vagina.
Why is colposcopy done?
Colposcopy is usually done in one of two circumstances: to examine the cervix either when the result of a Pap smear is abnormal, or when the cervix looks abnormal during the collection of a Pap smear. Even if a Pap smear result is normal, colposcopy is ordered when the cervix appears visibly abnormal to the clinician performing the Pap smear. The purpose of the colposcopy is to determine what is causing the abnormal looking cervix or the abnormal Pap smear so that appropriate treatment can be given.
How is colposcopy done?
A colposcope is a microscope that resembles a pair of binoculars. The instrument has a range of magnification lenses. It also has color filters that allow the physician to detect tiny abnormal blood vessels on the cervix. The colposcope is used to examine the vaginal walls and cervix through the vaginal opening.
- The first step of the procedure is examining the vulva and vagina for signs of genital warts or other growths. (Genital warts are caused by the human papilloma virus (HPV), which is a sexually transmitted virus that causes cervical cancer.)
- A Pap smear is then taken.
- The cervix is inspected and the special tests are done (see below).
Colposcopy is a safe procedure with no complications other than vaginal spotting of blood.
The examiner wants to get a good look at the squamocolumnar junction, which is the area of the cervix that gives rise to most cases of cervical cancer. The term squamocolumnar junction refers to the border between the two different types of cells (squamous cells and columnar cells) that normally form the lining of the endocervical canal. (This canal connects the cervix with the main part of the uterus.) Most cases of cervical cancer originate from the squamous cells and, therefore, are referred to as squamous cell cervical cancer.
During colposcopy, the entire squamocolumnar junction is more likely to be seen in young women. The reason for this is that after menopause, the squamocolumnar junction tends to migrate inside the endocervical canal. Colposcopy, therefore, is often not adequate in women after menopause. Therefore, if the whole squamocolumnar junction area of the cervix is not visible on colposcopy, another type of procedure may need to be performed that allows the entire squamocolumnar junction to be examined.
What special tests are done during colposcopy?
Three special tests are done during colposcopy: acetic acid wash, use of color filters, and sampling (biopsy) of tissues of the cervix.
Acetic acid wash
After the cervix is studied with the colposcope, the cervix is washed with a chemical called acetic acid, which is diluted 3% to 5%. The acetic acid washes away mucus and allows abnormal areas to be seen more easily with the colposcope. Moreover, the acetic acid stains the abnormal areas white. The areas that stain white after the acetic acid wash are called “acetowhite lesions.” Sometimes, however, normal areas can also stain white, but these areas have vague or faint borders. In contrast, significant abnormalities, such as genital warts, pre-cancers (dysplasia), and cancers, generally produce acetowhite areas with distinct and clear boundaries.
Sometimes staining with a dilute iodine solution (known as Lugol’s solution or Schiller’s solution) is also performed to further examine for abnormalities. Normal cells will generally take up the iodine stain (and turn brown) in a uniform manner, whereas severe precancers and cancerous areas will not.
Use of color filters
Another aspect of colposcopy involves the use of color filters. The filters help the physician examine tiny blood vessels (capillaries) in the area of the squamocolumnar junction. Blue or green filtered light can cause abnormal capillaries to become more obvious, usually inside an acetowhite area.
Normal capillaries are slender and spaced out evenly. In contrast, abnormal capillaries can appear as red spots (thickened capillaries seen on end) or can produce a pattern resembling hexagonal floor tiles. The worse the cervical disease, the thicker and more widely spaced out are the capillaries. The abnormal capillary pattern ranges from mild, as with pre-cancer (dysplasia), to severe, as with established cancer. Thus, when cancer eventually develops, capillaries take on odd shapes, like punctuation marks.
Biopsy of the cervix
Finally, colposcopy allows tissue sampling (biopsy) that is targeted to the abnormal areas. In fact, the biopsy of abnormal areas is a critical part of colposcopy because treatment will depend on how severe the abnormality is on the biopsy sample. After colposcopy and biopsies, a chemical is applied to the biopsy area to prevent bleeding (spotting). As part of the biopsy procedure, endocervical curettage (sampling of the tissues within the endocervical canal, or the opening of the cervix to the uterine cavity) is often performed.
Based on the colposcopy results, what is the approach to treating cervical abnormalities?
If the biopsy results show pre-cancer (dysplasia) or cancer, treatment is recommended. The dysplasia may be mild, moderate, or severe. Almost all women with dysplasia can have their treatment procedures performed in the doctor’s office. The physician chooses between two general types of treatment. The first type is destruction (ablation) of the abnormal area, and the second type is removal (resection). Both types of treatment cure 90% of patients with dysplasia, meaning that 10% of women will have a recurrence of their abnormality after treatment. Generally, destruction (ablation) procedures are used for milder dysplasia and removal (resection) is recommended for more severe dysplasia or cancer.
The destruction (ablation) procedures are carbon dioxide laser photoablation and cryocautery. The removal (resection) procedures are loop electrosurgical excision procedure (LEEP), cold knife conization, and hysterectomy. Only certain, carefully chosen cases of cervical cancer are treated with LEEP or cold knife conization. Most cases of cervical cancer and occasional cases of severe dysplasia are treated by hysterectomy. Treatment for dysplasia or cancer is not usually done at the time of the initial colposcopy, since the treatment depends on the analysis of the biopsies done during colposcopy.
What should a patient expect from each of the treatments for cervical abnormalities?
Carbon dioxide laser photoablation
This procedure, which is also known as CO2 laser, uses an invisible beam of infrared light. The laser actually vaporizes the abnormal area. Lidocaine, a local anesthetic, is given to numb the area prior to the laser treatment. A chemical is applied afterwards to prevent delayed bleeding. A substantial amount of clear vaginal discharge and spotting of blood can occur for a few weeks after the procedure. To improve healing, sexual intercourse and tampon use should be delayed for several weeks.
The complication rate of this procedure is very low, about 1%. The most common complications are narrowing (stenosis) of the cervical opening and delayed bleeding. Disadvantages of this treatment include that this procedure does not allow sampling of the abnormal area and is not satisfactory for treating cervical cancer. It is useful, however, for milder dysplasia. It is generally not considered safe for use during pregnancy.
Cryocautery is a relatively simple procedure that uses nitrous oxide to freeze the abnormal area. This technique, however, is not optimal for large areas or areas where abnormalities are already advanced or severe. After the procedure, patients can experience a significant watery vaginal discharge for several weeks. To improve healing, sexual intercourse is best avoided for several weeks.
Significant complications of this procedure are rare and occur in about 1% of patients. They include narrowing (stenosis) of the cervix and delayed bleeding. Cryocautery does not allow sampling of the abnormal area and is generally felt to be inappropriate for women with advanced cervical disease. Thus, this procedure is not satisfactory for treating cervical cancer, but is useful for milder dysplasia.
Loop electrosurgical excision procedure
Loop electrosurgical excision procedure, also known as LEEP, uses a radio-frequency current to remove abnormal areas. It has an advantage, therefore, over the destructive techniques (CO2 laser and cryocautery) in that an intact tissue sample for analysis can be obtained. LEEP also is popular because it is inexpensive and simple. A chemical is applied afterwards to prevent bleeding. Vaginal discharge and spotting commonly occur after this procedure. Sexual intercourse and tampon use should be avoided for several weeks to allow better healing.
Complications occur in about 1% to 2% of women undergoing LEEP, and include cervical narrowing (stenosis) and bleeding. This procedure is used most commonly for treating dysplasia, including severe dysplasia. LEEP also is used, although infrequently, to treat carefully chosen cases of cervical cancer.
Cold knife cone biopsy (conization)
Cone biopsy was once the major procedure used to treat cervical dysplasia, but the other methods have now replaced it for this purpose. However, when a physician cannot view the entire area that needs to be seen during colposcopy, a cone biopsy continues to be recommended. It is also recommended if special sampling is needed to obtain more information regarding certain types of more advanced abnormalities. This technique allows the size and shape of the sampling to be tailored.
Complications of this procedure include postoperative bleeding in 5% of women and narrowing of the cervix. Cone biopsy has a slightly higher risk of cervical complications than the other treatments. This procedure is occasionally used to treat carefully chosen cases of cervical cancer.