You are in: eMedicine Specialties > Obstetrics and Gynecology > Gynecologic Surgery Carbon Dioxide Laser Surgery of the Lower Genital TractArticle Last Updated: Sep 7, 2006AUTHOR AND EDITOR INFORMATIONSection 1 of 7
  Author: Livia Shang-yu Wan, MD, Director, Division of Endoscopic Pelvic Surgery, Professor of Obstetrics and Gynecology, Department of Obstetrics and Gynecology, New York University School of Medicine Livia Shang-yu Wan is a member of the following medical societies: American College of Obstetricians and Gynecologists, American Society for Reproductive Medicine, Association of Professors of Gynecology and Obstetrics, Association of Reproductive Health Professionals, Medical Society of the State of New York, and Society of Laparoendoscopic Surgeons Editors: Karen Loeb Lifford, MD, Director of General Gynecology, Associate Program Director, Department of Obstetrics and Gynecology, Instructor, Brigham and Women's Hospital, Harvard Medical School; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; David Chelmow, MD, Professor of Obstetrics and Gynecology, Tufts University School of Medicine; Program Director, Tufts University Affiliated Hospitals OB/GYN Residency Program; Chair, Tufts University Health Sciences Campus Institutional Review Board; Frederick B Gaupp, MD, Consulting Staff, Department of Family Practice, Hancock Medical Center; David Chelmow, MD, Professor of Obstetrics and Gynecology, Tufts University School of Medicine; Program Director, Tufts University Affiliated Hospitals OB/GYN Residency Program; Chair, Tufts University Health Sciences Campus Institutional Review Board Author and Editor Disclosure Synonyms and related keywords: light amplification by stimulated emission of radiation, LASER, CO2 laser, endometriosis ablation, lysis of pelvic adhesions, cervical intraepithelial neoplasia, CIN, vaginal intraepithelial neoplasia, VAIN, vulvar intraepithelial neoplasia, VIN, human papillomavirus, HPV, carcinoma in situ, CIS, vaginal condyloma, vulvar condyloma INTRODUCTIONSection 2 of 7
  With the development of light amplification by stimulated emission of radiation (LASER) for medical use in early 1970 (Anderson, 1982), the carbon dioxide (CO2) laser was adapted to the laparoscope and colposcope, which opened a new era of laser treatment for patients with gynecologic diseases. The CO2 laser was used via laparoscope for conditions such as endometriosis ablation and lysis of pelvic adhesions. Through the colposcope, the CO2 laser was used for vaporization or conization of cervical intraepithelial neoplasia (CIN) (Carter, 1978; Dorsey, 1980; Baggish, 1980; Masterson, 1981; Bellina, 1981; Beneder, 1981; Burke, 1982; Anderson, 1982; Baggish, 1982; Fallani 2003) or vaporization of vaginal intraepithelial neoplasia (VAIN) (Stafl, 1977; Townsend, 1982; Jobson, 1991) and vulvar intraepithelial neoplasia (VIN) (Baggish, 1981; Leuchter, 1984; Sideri, 1999). These lesions primarily result from previous human papillomavirus (HPV) infection (see Human Papillomavirus). Reportedly, laser treatment is more advantageous than cryotherapy (Townsend, 1981; Townsend, 1983) or cold knife conization (Larsson, 1982). In recent years, the use of laser for CIN has been gradually replaced by the loop electrical excision procedure (LEEP) for biopsy or conization. A randomized study compared 3 different techniques for cervical conization with cold knife, laser, or LEEP for its recurrence rate and complications during subsequent pregnancy. No statistical differences among the methods were found (Mathevet, 2003). The use of laser treatment for vaginal and vulvar diseases remains one of the best treatment methods (Penna, 2002). For excellent patient education resources, visit eMedicine's Cancer and Tumors Center. Also, see eMedicine's patient education article Cervical Cancer. THE PHYSICAL PRINCIPLES OF CARBON DIOXIDE LASER TREATMENTSection 3 of 7
The CO2 laser is an invisible laser beam of infrared light, with a wavelength of 10,600 nm. The beam is generated by exciting CO2 molecules in an optic resonator. This laser is a monochromatic, coherent, and collimated emission delivered as a noncontact free beam. Water is the target chromophore for the CO2 laser. Any tissue containing water can absorb the laser energy and produce heat sufficient to vaporize the tissue. Advantages of the high-power CO2 laser include the following:
By adjusting the power density (PD), the CO2 laser can be used for cutting (similar to a knife) or for vaporization of tissue. The factors affecting PD include the following:
The PD can be calculated by the following simple formula: PD = Power (in watts [W]) X 100/spot size (spot diameter in cm2). Defocusing the beam increases the spot size, changing the power density. The average PD required for vaporization is 700-1000 W/cm2. For cutting, vaporization requires a higher PD, ie, as much as 1000-1200 W/cm2. The CO2 laser beam can be delivered in an intermittent or continuous mode, but the continuous mode is preferred for gynecologic procedures (Kohan, 1984). Laser safety The laser beam can injure tissue other than the site being treated. The laser should not be turned on until the surgeon is ready to start, and it should be turned off as soon as the intended procedure is completed to avoid accidental discharge of laser beam. The perineum should be covered with a wet cloth to protect the areas near the site being treated. The wet cloth absorbs the laser energy, thus protecting the tissue under the cloth. Flammable paper drapes should not be near the operating field. This material can be set on fire by the laser. Any material such as metal or mirror that can reflect the laser should not be used because it could lead to inadvertent injury to the patient or surgical team. The metal instruments used for laser surgery such as the speculum, hooks, and measuring rod should be anodized or sand brushed to prevent laser reflection. The surgeon and other personnel in the operating room can be injured accidentally. Eye protection is necessary for everyone present during the procedure. A sign indicating that the laser is in use should be posted on all doors to the operating room to prevent anybody entering the room without eye protection. Extra goggles and laser masks should be available outside the door for staff members who may need to enter the room while the surgery is in progress. Laser masks should also be used by all staff members in the operating room to prevent the inhalation of viral particles in the laser plume. A suction apparatus with filter should be used to evacuate the smoke generated during the procedure. Periodic maintenance of the laser machine is essential to ensure that the machine is functioning well, without any leak of laser energy. USE OF CARBON DIOXIDE LASER IN THE LOWER GENITAL TRACTSection 4 of 7
Cervical lesions Since the late 1970s, cervical lesions, including CIN, carcinoma in situ (CIS), and condyloma have been treated with the CO2 laser. In the 1980s, this laser was one of the popular methods for the treatment of patients with CIN. By using the colposcope, the CO2 laser can be delivered to the desired site in a very precise way. A micromanipulator can be used to direct the laser beam and to vaporize the lesion under direct vision with adequate margin and depth. Prior to laser, the popular method for treatment of patients with CIN was cryotherapy. Laser treatment was found to have fewer adverse effects and sequelae; however, performing adequate laser surgery requires an understanding of laser principles and familiarity with the handling of instruments via a colposcope. The CO2 laser can also be delivered with a handheld instrument after colposcopic examination and application of Lugol solution to identify the areas with the lesion. Laser vaporization with a handheld instrument is less precise than colposcopy with a micromanipulator. Laser treatment of cervical lesions uses the following 2 methods:
The advantages of CO2 laser vaporization are the ability to identify the margin of the lesion via a colposcope and to vaporize to the desired depth. Because of the special characteristics of the CO2 laser, the surgeon can visualize (through the colposcope) the depth to which the tissue is vaporized and whether the tissue underneath is injured or damaged can be determined. An average depth of 3-5 mm is required in patients with CIN I or II lesions. For patients with CIN III or CIS lesions, the depth of vaporization should be deeper (5-7 mm), including the crypts of the endocervical glands. A high PD should be used. The smaller the spot size, the higher the PD and the better the vaporization or cutting effect. The area to be vaporized should be delineated by marking with the laser beam at the anterior (12 o'clock), the posterior (6 o'clock), and both lateral sides (3 and 9 o'clock); then, these 4 dots should be connected to make a circle that surrounds the area to be vaporized with an adequate margin. Next, a cross (+) should be outlined inside the circle to divide the circled cervix into 4 quarters (see Images 11-14). Vaporization is conducted quarter by quarter by moving the laser beam and systematically covering the entire area to the desired depth. Vaporizing the entire squamocolumnar junction and the transitional zone of the cervix is important. Excisional conization can be performed with a CO2 laser under colposcopic guidance by using the laser beam with a small spot size and high PD (1000-1200 W/cm2). The laser can cut like a knife, vaporizing only a minimal amount of tissue. Consequently, less destruction of the specimen occurs, allowing better demonstration of any involvement of the specimen's margin. After the cone specimen is removed, the margin of the epithelium can be vaporized further for an additional 1-2 mm to decrease the risk of any residual disease. As with a cold knife cone, the tip of the cone should be at least 1 cm below the internal os to decrease the risk of an incompetent cervix in future pregnancy. Cervical condyloma can also be treated with a CO2 laser (eg, CIN lesions), except the required depth of vaporization is only 2-3 mm. Reports of persistent lesions after a single CO2 laser treatment for CIN range from 7% (Bellina, 1981) to 23.6% (Anderson, 1982) in early reports. Recently, a 5-year follow-up study by Fallani et al reported no intraoperative or postoperative complications. The cure rate for a single treatment was 97.5%, and a satisfactory colposcopic follow-up was possible in 99.4% of treated patients (Fallani, 2003). Posttreatment, patients must be monitored with a Papanicolaou test (Pap smear) and colposcopy after any abnormal cytology findings are discovered. Primary failure can be re-treated with the laser. In a randomized trial (Townsend, 1983), no statistically significant difference was found in the effectiveness of CO2 laser vaporization and cryotherapy for CIN (11% versus 9%). The effectiveness of CO2 laser vaporization for CIN is the same as cryotherapy; however, with laser treatment, healing of the operative site seems to be completed without scarring of the cervix. The cervical os remains open, and the squamocolumnar junction can be visualized easily after laser treatment (Townsend, 1983). Laser excisional conization was compared with cold knife conization (Larsson, 1982), and the laser cone was associated with minimal bleeding during surgery, faster healing than the cold knife cone, and a decreased incidence of delayed hemorrhage (1.8% versus 14.6%). Since the development of LEEP, more gynecologists now are using this method for routine diagnosis and treatment in patients with cervical lesions, including CIN and CIS. The reasons for the change include the following:
Vaginal lesions Patients with vaginal condyloma can be treated with excision if they have only a solitary large lesion. Laser vaporization is better suited for multiple and smaller lesions. The laser can be guided via colposcope or a handheld tip. Vaporization of vaginal condyloma should not be too deep because condyloma is a surface lesion. Vaporization of the superficial epithelial layer with at least 1 cm of margin around the lesion is adequate. The advantage of using the CO2 laser is the ability to treat a large area without causing a scar, stricture, or narrowing of the lumen (Townsend, 1982). Deep penetration with an electric instrument (eg, LEEP) may injure the organs underneath the vaginal wall (eg, rectum, bladder) (Powell, 2000). Obtain a biopsy with an adequate margin in a solitary vaginal intraepithelial neoplasia (VAIN) lesion; therefore, performing an excision with a knife is best. Yalcin et al used CO2 to treat 24 women with VAIN II or VAIN III lesions. The mean follow-up time was 26.7 months with a range of 7.1-46.3 months. No early or late major complications were observed. VAIN was completely eliminated in 70.8% of the women after first treatment and 79.2% after repeated treatment. One patient progressed to invasive cancer. Yalcin et al identified no prognostic factors for persistent lesion or progression of the lesion. They stressed close follow-up for persistence, recurrence, or progression of the lesion (Yalcin, 2003). VAIN can develop after hysterectomy, especially in patients with previous CIN, CIS, or cervical cancer. Colposcopic identification of the lesion and confirmatory biopsy are essential before treatment. CO2 vaporization is one of the most effective and least invasive treatment methods. Sherman reported successful treatment in 143 patients with vaginal cuff VAIN after hysterectomy (Sherman, 1990). Vulvar lesions Many vulvar lesions have been treated with the CO2 laser, with good results. Vulvar condyloma and VIN, including vulvar CIS, have been treated successfully with the CO2 laser (Baggish, 1981; Leuchter, 1984; Sideri, 1999). Ablation of the dermis layer is adequate for condyloma. VIN lesions require a slightly deeper ablation (2-3 mm). Vaporization of the skin that is too deep causes scarring (Reid, 1985). Washing the lesions with 5% acetic acid can aid in identifying the involved areas. Laser ablation should be performed approximately 1 cm beyond the margin of the lesion to decrease recurrence. As reported by Penna, either vaporization or excision with laser was used for the treatment of VIN; they were effective in a single treatment in 76.9% and 78.4% of cases, respectively. Second laser treatment for recurrent VIN achieved a total of 96.8% cure. All cases were performed at ambulatory setting under local anesthesia (Penna, 2002). Laser excision for VIN-3 has the advantage of helping to rule out any invasion. Recent reports by Brown suggested that using laser vaporization after partial vulvectomy for VIN II or VIN III was associated with a lower recurrence rate as a combined procedure than either modality alone (Brown, 2005). Case reports of treatment of other vulvar lesions (eg, molluscum contagiosum, lichen sclerosis atrophica, chronic vestibulitis, other dermatologic lesions) with the CO2 laser suggest good results (Kaufman, 1985; Kartamaa, 1997; Reid, 1991). Preoperative and postoperative care Preoperative colposcopic and biopsy diagnosis of the lesion is a prerequisite for laser treatment. Individualize preoperative counseling and discussion about the options for each patient. Postoperative pain is usually minimal for cervical and vaginal lesions and can be treated with any analgesic other than aspirin. The pain following laser treatment of a vulvar lesion can be severe. Local treatment with lidocaine gel and stronger analgesics may be needed. In addition, local care with sitz baths can help relieve pain and prevent infection of the laser sites. Warn patients about the possibility of bleeding, especially after conization. Patients having treatment of the cervix or vagina should be cautioned not to use tampons, douche, or have vaginal intercourse for at least 2 weeks to allow proper healing. Complications Bleeding at the time of surgery can be easily managed by defocusing the beam for coagulation effect or using electric coagulation. Delayed hemorrhage after laser cervical conization can occur about 7-10 days postoperatively. However, it is much less frequent than with cold knife conization (Larsson, 1982). Treatment with Monsel solution is usually effective to stop bleeding. The risk of preterm delivery was increased with cervical conization by LEEP, laser, or cold knife cone when the conization was too deep. The risk was increased with increasing height of cervical tissue removed. No such risk was found in laser vaporization cases (Sadler, 2004). Injury caused by improper use of laser energy or accidental burn to the patient and staff is possible. Proper draping and eyewear are important. Rectal injury is possible during laser treatment of vaginal lesions of the posterior wall when the laser beam penetrates too deeply. Prolonged vulvar pain or vulvodynia with atrophic changes of mucosa was reported following laser vaporization of vulvar condylomata acuminata or bowenoid papulosis (Tschanz, 2001). Disfiguring scar formation or narrowing of the introitus can occur when the vulvar or vaginal lesions are extensive and laser treatment is too deep (Reid, 1985; Townsend, 1982). CONCLUSIONSection 5 of 7
The CO2 laser is a very useful tool for treating patients with various lesions in the lower genital tract. With the proper setting, the CO2 laser can be used for cutting (ie, like a knife), for vaporizing the affected tissue, or for coagulation or hemostasis. However, the procedure requires special training for the users, and the instrumentation is costly. Despite these drawbacks, the CO2 laser remains a very effective method for treating patients with various lesions in the lower genital tract. MULTIMEDIASection 6 of 7
REFERENCESSection 7 of 7
Carbon Dioxide Laser Surgery of the Lower Genital Tract excerpt Article Last Updated: Sep 7, 2006 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
