eMedicine Specialties > Obstetrics and Gynecology > Gynecologic Surgery

Carbon Dioxide Laser Surgery for Cervical Dysplasia: Treatment

Author: Janice L Bacon, MD, Professor and Chair, Department of Obstetrics and Gynecology, University of South Carolina School of Medicine
Contributor Information and Disclosures

Updated: Dec 5, 2007

Treatment

Surgical Therapy

Anesthesia is provided by local injection of lidocaine with or without epinephrine. It may be accompanied by sedation, if desired by the physician or patient. When performed in a surgical suite with anesthesia personnel, additional intravenous, regional, or general agents may be used.

Preoperative Details

Positioning

The patient is placed in a dorsal lithotomy position, and a speculum of adequate size is used to fully visualize the cervix. Use a speculum with a dull surface that is specifically designed to reduce indirect reflection of the laser beam. Take care to choose a speculum of appropriate length and width to prevent relaxation of the lateral vaginal walls, limiting cervical exposure and risking inadvertent laser damage.

The patient is draped in damp towels to absorb any misdirected laser beams, and the patient's eyes are protected appropriately in wet gauze or protective glasses. All personnel, except the physician operating the microscope, should also wear eye protection.

The cervix is bathed in a 3% solution of acetic acid, and the cervical abnormalities are noted again before the laser is fired.

A smoke evacuator system is used to remove the vapor plume. This is accomplished most efficiently with (1) a suction catheter attached to the speculum, with a conduit toward the cervix to maximize plume removal, or (2) a suction tip placed as far into the vagina as possible without interfering with the laser beam. Custom specula with smoke evacuation attachments are commercially available.

Setting the laser

The desired power-density range for adequate ablation or excision with minimal thermal damage to adjacent areas is 750-2000 W/cm² (generally, 20-30 W at a continuous setting), with an effective beam diameter of 1.5-2 mm to maximize ablation and hemostasis while minimizing lateral thermal damage. Super-pulse settings also may be used, and they are preferred by some to also reduce thermal damage.¹⁰ The same laser settings may be used to coagulate the portions of the cervix being ablated or excised, but the overall power density delivered for coagulation may be reduced by enlarging the dot size or by reducing the watt setting on the laser, thus decreasing the watts used per cm².

Intraoperative Details

The entire transformation zone is identified and marked with an intermittent beam application, taking care to be at least 3-4 mm beyond the affected area of the cervix. If an adequate margin cannot be obtained, another type of treatment may be indicated. The entire circumference of the anticipated ablation area is outlined as if outlining a circle with dots. These dots are then connected, and the entire area is ablated with a consistent continuous movement of the laser beam. The area is measured periodically with a graduated probe, and the ablation continues to a depth of 7-10 mm. Ablation to an additional depth of 2 mm may be performed at the endocervical margin.

Any bleeding points encountered are treated with coagulation by increasing the dot size or decreasing the power. Additional ablation at the endocervix allows destruction of disease in gland crypts.

A lesion that is difficult to see may be observed in its entirety through the colposcope, through manipulation of the speculum, or with the use of skin hooks to manipulate the cervix. A probe also may allow a change in angle to more completely visualize the endocervical opening. In addition, using a vaginal sidewall retractor helps prevent redundant vaginal sidewalls from obscuring vision and helps avoid inadvertent thermal damage. All equipment used must be coated or treated to prevent reflection of stray laser beams.

For excisional procedures, the dots are connected and the initial depth is taken to approximately 5 mm. Periodic measurements are performed using a graduated probe. Once a depth of 5 mm is reached, a skin-hook (with a dull surface) is used to pull the specimen medially from all directions while simultaneously firing the laser beam, thus creating a cone-shaped specimen. Once the endocervix is reached, many physicians make the final cut with a knife or scissors to allow the cephalad margin to be more easily evaluated by the pathologist. Bleeding during the excisional procedure or after the specimen is removed from the site is controlled with the laser, by defocusing the beam (increasing the dot size), decreasing the wattage, or both.

Postoperative Details

The frequency of postoperative cytologic testing should be correlated to the disease detected at the time of excisional procedures. The American College of Obstetricians and Gynecologists (ACOG) Practice Bulletin recommends the following:¹¹  

• CIN 1 with positive margins should have cytologic testing at 6 and 12 months postoperatively or high-risk HPV testing at 12 months postoperatively. 
• Positive margins for a specimen revealing CIN 2, 3 or a positive endocervical sampling for squamous CIN after excisional procedure, indicates persistent disease. Follow-up with endocervical sampling is indicated, though re-excision is not required.
• High-risk HPV typing may be an alternative to cytologic testing after therapy for CIN 2, 3. This may be performed 6 months following therapy. HPV typing may be performed 12 months after the diagnosis of CIN 2, 3 in adolescent women.
• After treatment for CIN 2, 3, cytologic testing 3-4 times at 6-month intervals is recommended.

Follow-up

Postoperative patient instructions may vary from one provider to another and may also allow changes in accordance with additional patient medical conditions. General postoperative instructions frequently include (1) pelvic rest (ie, no tampons, douching, or intercourse) until the scheduled postoperative follow-up examination; (2) light activity for 3-5 days postoperatively, especially no heavy lifting or excessive strenuous activities; and (3) instructions to call if a foul vaginal discharge, pelvic pain, fever, or excess bleeding develops.

CIN Grade 1

CIN 1 lesions are heterogeneous; most are associated with the presence of high risk types of HPV. Others are also heterogeneous with respect to markers of neoplasia. CIN 1 rarely progresses to CIN 2 or 3 and the risk of having an undetected higher-grade lesion is greater if the biopsy diagnosis of CIN 1 was preceded by cytology showing HSIL or AGC. The recommended management of women with CIN 1 preceded by ASCUS, ASC-H, or LSIL cytology is follow-up cytology with either high-risk HPV DNA testing every 12 months or cervical cytology every 6-12 months. If test results for high-risk HPV are positive, or if repeat cytologic results are ASCUS or greater, colposcopy is recommended. If high-risk HPV test results are negative or 2 consecutive cytology test results are negative, a return to routine annual cytologic screening is recommended. 

If conservative management with cytology and colposcopy is chosen, a diagnostic excisional procedure is recommended for women whose cytologic results at 6 or 12 months show HSIL. In adolescent patients with CIN 1, those with HSIL or greater cytologic abnormalities at the 12-month follow-up should be referred for colposcopy. Management of the pregnant woman with biopsy proven CIN 1 is follow-up cytologic testing after delivery.  
 
CIN Grade 2, 3

While more than 40% of untreated CIN 2 lesions regress without interventional therapy, approximately one third will persist and 22% will progress to carcinoma in situ or invasive cervical disease.¹² The procedures for cervical ablation or excisional methods can be used to treat women with biopsy confirmed CIN 2, 3 and a satisfactory colposcopic examination. An excisional procedure with positive pathology at the margins followed by an unsatisfactory colposcopy is generally considered a risk factor for recurrent or persistent CIN. 

At the time of a diagnostic procedure, endocervical sampling correlates with endocervical margin status. Positive evidence of disease at the endocervical margin is predictive of residual dysplasia in 10-33% of recent studies.¹³  Women are recommended to be counseled about their increased risk for recurrent or persistent CIN when pathology results following treatment reveal positive margins. For those patients in which further treatment is decided upon, an excisional procedure may be preferred with hysterectomy also a viable option for women who have completed child bearing.  
 
Follow-up for women with CIN 2, 3 includes HPV DNA testing at 6-12 months or follow-up using cytology and colposcopy at 6-month intervals (provided colposcopy is satisfactory). Colposcopy and endocervical sampling is recommended for women who are high-risk HPV DNA positive or have a repeat cytologic result of ASCUS or higher. If the HPV test result is negative or if 2 consecutive repeat cytology tests are negative for CIN, routine annually screening may be recommended. If CIN 2, 3 is present at the margins of an excisional procedure or in an endocervical sample obtained immediately following the procedure, a reassessment of the patient by cytology and endocervical sampling is recommended in 4-6 months following the initial treatment. In some patients, a repeat excisional procedure or even hysterectomy may be acceptable options for women with persistent, moderate, or severe dysplasia, or recurrent CIN 2, 3. 
 
For adolescent and young women with CIN 2, 3, treatment or observation using both colposcopy and cytology at 6-month intervals is acceptable as long as the colposcopy is satisfactory. Surveillance should be maintained for 24 months. In pregnant women, additional colposcopic and cytologic examinations may be performed at intervals no more frequently than every 12 weeks with reevaluation after 6 weeks postpartum.    
 
Adenocarcinoma in situ

The management of adenocarcinoma in situ is often difficult since this disease process frequently extends well into the endocervical canal and may be multifocal or possess "skip lesions." Therefore, negative margins performed after an excisional procedure do not guarantee the disease has been completely removed. In most patients, however, an excisional procedure is curative. The failure rate following an excisional procedure ranges from 0-9%.¹⁴ Positive endocervical cytology at the time of an excisional procedure may also be indicative of residual disease. 
 
Hysterectomy is preferred as a management strategy in women who have completed childbearing and possessed the diagnosis of AIS at the time of an excisional procedure. If childbearing has not been completed, reevaluation in 6 months using combined cervical cytology, HPV DNA testing, and colposcopy with endocervical sampling is acceptable. For those women who decline hysterectomy at the completion of childbearing, long-term follow up is recommended.  

For excellent patient education resources, visit eMedicine's Cancer and Tumors Center. Also, see eMedicine's patient education article Cervical Cancer.

Complications

Complications associated with ablative or excisional procedures performed using the carbon dioxide laser include bleeding, infection, cervical scarring or stenosis, altered fertility, anesthetic complications, premature labor, and incompetent cervix.

Bleeding may occur at the time of the procedure or 4-10 days after the procedure. Procedural blood loss may be minimized by scheduling the procedure during the follicular phase of the menstrual cycle.

Bleeding in the days following the procedure represents arterial recanalization. Inspection of the operative site should be performed at any point if the patient feels the amount of bleeding is worrisome. Topical treatments (eg, Monsel solution, silver nitrate) may be applied to any specific bleeding sites. Visualization of a clot in the surgical bed, without evidence of active bleeding, warrants observation only. Removing the clot often causes the bleeding to resume. The patient should be advised to call if persistent bleeding occurs (usually described as heavier than a period).

The rate of bleeding after laser procedures has been reported to be similar to that following a LEEP but less than that following a cold-knife conization procedure.¹⁵ The risk of bleeding following an uncomplicated laser ablation of the transformation zone, including all risks of bleeding (ie, acute, immediate, and following the procedure), is approximately 5% overall.

Long-term complications following laser procedures of the uterine cervix include possible reduced ability to visualize the transformation zone. This can occur after any surgical procedure of the cervix. A preventive technique called buttoning may be performed at the time of the procedure and has been helpful in attempting to maintain visualization of the transformation zone. This involves vaporizing the cervical stroma 1-2 mm immediately surrounding the endocervical os. This assists with the eversion of the endometrial mucosa when healing occurs.¹⁶

Ablative or excisional laser procedures and recurrent or multiple procedures are also associated with cervical stenosis and may be associated with a loss of endocervical glands due to lasering close to the proximity of the internal os. This may be preventable by attempting smaller volumes of cervical destruction (if feasible without compromising the anticipated disease associated with the case). In postmenopausal women, the incidence of stenosis may be reduced with the adjunctive administration of vaginal estrogen cream postoperatively (Penna, 2005).

Any surgical procedure on the uterine cervix, especially recurrent procedures or the destruction of a large volume of cervical tissue, is associated with a loss of cervical volume and may result in an incompetent cervix or premature labor.^17,18 However, fertility rates are not generally altered by a single procedure. Rates may be reduced following multiple procedures. This would occur because of destruction of the endocervical glands, resulting in decreased numbers of endocervical glands and leading to a reduced amount of endocervical mucus or to secondary cervical stenosis.

Anesthetic complications include risks associated with local anesthesia and systemic absorption of the anesthetic agent. These include tingling in the ears, dizziness, and, rarely, seizures and cardiac arrest. Care in these instances consists of symptomatic measures and, if seizures or cardiac arrest occurs, transfer for hospitalization and evaluation. Office procedures should only be performed when staff and equipment are available to deal with any emergency, including items and persons for cardiopulmonary resuscitation and a "crash" cart. Patients with known preexisting medical disorders (eg, seizure disorder) should be considered for procedures in a surgical suite with anesthesia administered by a physician or nurse anesthetist.

Infection can occur after any ablative or excisional procedure on the cervix. Normal healing following carbon dioxide laser procedures is accompanied by a moderate, malodorous cervical discharge associated with sloughing of dead cells. This also occurs following LEEPs or cryotherapy. This discharge may be difficult to distinguish from infectious discharge, but signs of true infection include pelvic pain, fever, and symptoms of salpingitis. The presence of cervical infection may also manifest as prolonged bleeding or delayed healing postoperatively.

Bleeding can be decreased by scheduling the procedure during the week following menses (ie, the follicular phase). Careful visual inspection of the cervix and vagina, judicious testing for sexually transmitted disease, and a wet mount examination of the vagina prior to surgery may allow preoperative eradication of potential agents of infection (eg, gonorrhea, chlamydia, bacterial vaginosis).

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