Cervical Cryotherapy

E. J. Mayeaux, Jr., MD, DABFP, FAAFP
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Subject: Cervical Cryotherapy

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Introduction

Cryotherapy is a time-proven, ablative method of treating lower grades of cervical dysplasia. The procedure is easy to learn, perform, and apply in outpatient settings. It works by freezing and killing abnormal tissue, which then sloughs off, and new tissue grows in its place. The tip of the cryoprobe is cooled by a refrigerant gas that is fed into the hollow cryoprobe under pressure. The gas then rapidly expands, absorbing heat in the process. The temperature of a nitrous oxide probe tip falls to -65°C to -85°C. A water-soluble lubricant is applied to the probe to act as a thermocouple with the irregular surface of the cervix. This produces a more uniform freeze. A rapid freeze followed by a slow thaw maximizes cryonecrosis, and a freeze–thaw–refreeze cycle is more effective than a single freeze. 
After the cryoprobe is placed in contact with the cervix and activated, a ring of frozen tissue, or ice ball, extends outward. The depth of freeze approximates the lateral spread of the freeze. Cell death occurs when the temperature falls to <-10°F. However, there is a ring of tissue (i.e., thermal injury or recovery zone) that freezes but does not reach the -10°F necessary for cell death. This is why it is necessary to freeze well beyond the margins of any lesions. Studies have demonstrated that endocervical crypt (gland) involvement of cervical intraepithelial neoplasia (CIN) may penetrate up to 3.8 mm into the cervix. A freeze that causes cell death to 4 mm should effectively eradicate 99.7% of lesions with gland involvement. Current recommendations are to produce an ice ball with a 5-mm lateral spread to accomplish this goal. 
The cryotherapy appointment should be scheduled when the patient is not experiencing heavy menstrual flow. Select the largest speculum that the patient can comfortably tolerate, and open the blades and the front end of the speculum as widely as possible without discomfort. If collapsing side walls are a problem, place a condom with the tip cut off, the thumb from a very large rubber glove with the tip cut off, or one half of a Penrose drain over the speculum. Alternatively, tongue blades or sidewall retractors may be placed to improve exposure. 
The choice of treatment modality for cervical dysplasia is at the discretion of the health-care provider. It is well established that cold knife conization increases a woman’s risk of future preterm labor, low-birth-weight infant, and cesarean section. Several large retrospective series have now reported that women who have undergone a loop excision procedure (LEEP) or laser conization are also at increased risk for future preterm delivery, low-birth-weight infant, and premature rupture of membranes. The recent American Society for Colposcopy and Cervical Pathology (NCI/ASCCP) consensus guidelines note that, although cryotherapy studies have not shown these adverse effects on pregnancy outcome, it is difficult to measure small effects on pregnancy outcome. Therefore, some experts recommend cervical cryotherapy over LEEP for treatment of appropriately selected reproductive-age women. Advantages and disadvantages of cryotherapy appear in Table 73-1
No anesthetic is required before cryotherapy because the procedure is relatively painless, although some cramping may occur. Some physicians recommend the use of nonsteroidal anti-inflammatory drugs to decrease cramping. Submucosal injection of 1% lidocaine with epinephrine (1:100,000) can be administered to decrease local pain. 
 
TABLE 73-1.
Advantages and Disadvantages of Cervical Cryotherapy
The most common minor complication occurs if the probe touches the vaginal side wall and adheres to it. This causes pain, and bleeding may occur from the injured vaginal mucosa. Occasionally, a patient may experience an undue amount of pain and cramping, which is usually associated with a high level of anxiety. If this can be anticipated, a paracervical block before cryotherapy, oral or intramuscular administration of benzodiazepines (e.g., 1 mg of lorazepam [Ativan] given intramuscularly), or intravenous sedation may be chosen for relief. These measures are seldom required. 
Rarely, a patient may experience a vasovagal reaction. Allowing the patient to rest on the examination table after the procedure and to get up slowly is usually sufficient to overcome this problem. There has been a reported case of anaphylaxis due to cold urticaria. Some concern has been raised about occupational exposure to vented NO2 gas following cryotherapy, but the scientific evidence for harm is very weak. 
The patient should refrain from sexual intercourse and tampon use for 3 weeks after cryotherapy to allow the cervix to re-epithelialize. Excessive exercise also should be discouraged to lessen the chance of bleeding after treatment. 
Most patients experience a heavy and often odorous discharge for the first month after cryotherapy. About one half of women rate the postprocedure discharge and its odor worse than a normal period. This discharge results from the sloughing of dead tissue and exudate from the treatment site. Routine cervical eschar debridement does not shorten the duration or amount of discharge and offers no significant advantage. Amino acids/sodium propionate/urea cervical cream (Amino-Cerv) cream may be prescribed if a heavy discharge is present after the procedure, although there is no scientific evidence of efficacy. Approximately one third of patients restrict their activities because of side effects of the procedure. 
The first follow-up Papanicolaou (Pap) smear should not be performed for 6 months. Cytology can be very confusing if sampled during the sloughing or regenerative phases, which take at least 3 months to complete. If the first two follow-up smears are normal, Pap smears can be repeated every 6 months until two normal tests are obtained. Most recurrences take place within 2 years of treatment. Annual smears may be recommended after 2 years. An alternative follow-up schedule involves replacing the initial and each annual Pap smear with a colposcopic examination. Unfortunately, patient compliance with serial cytology follow-up is suboptimal. 
If any of the follow-up tests are positive, restart the workup as if there was a newly diagnosed, first-time dysplasia. Colposcopy with directed biopsy is usually indicated. Unfortunately, colposcopy after cryotherapy may be more difficult because of migration of the squamocolumnar junction deeper into the cervical os. Other treatment methods (usually LEEP) are preferred if persistent disease is discovered. 

Equipment

  • The device consists of a gas tank containing nonexplosive, nontoxic gases (usually nitrous oxide but sometimes carbon dioxide).

  • A 20-lb gas cylinder is preferable to the 6-lb E-type tank, because the former has a more efficient pressure release curve.

  • Liquid nitrogen has been used in the past, but it is difficult to control and is not recommended.

  • Tanks are usually obtained from local suppliers.

  • Appropriately sized vaginal specula.

  • Adequate light source.

  • Cervical probes in a variety of sizes.

  • Water-soluble lubricant.

Indications

  • Treatment of biopsy-proven cervical intraepithelial neoplasia 2 and 3 lesions

  • Cervical intraepithelial neoplasia (CIN) 1 lesions persistent for 2 or more years, especially in women who do not wish to have children

Contraindications

  • An unsatisfactory colposcopic examination.

  • A lesion that extends more than 3 or 4 mm into the cervical os because the area of destruction may not reliably penetrate beyond this level.

  • A positive endocervical curettage.

  • A lesion that covers more than two quadrants of the cervix.

  • A lesion that cannot be completely covered by the cryoprobe.

  • CIN 3 lesions (relative contraindication). There may be a higher recurrence rate compared with LEEP for CIN 3 level lesions, possibly because of the greater depth of glandular involvement with CIN 3.

  • A mismatch of cytologic, histologic, and colposcopic findings greater than two histologic grades.

  • Pregnancy.

  • Active cervicitis.

  • Some physicians recommend using an excisional therapy (e.g., LEEP) for recurrent dysplasia after ablative therapy.

  • Adenocarcinoma in situ (should have cold knife conization).

  • Unsatisfactory colposcopy.

  • Lesion not fully visible or extending beyond the range of the cryotherapy probe.

  • Biopsy consistent with or suspicious for invasive carcinoma.

The Procedure

Step 1

Informed consent is obtained. Perform a pregnancy test if there is any doubt about the patient’s pregnancy status. Make sure that there is adequate pressure in the tank; usually, the needle is in the “green zone” on the pressure gauge. 

Step 2

Place the patient in the dorsal lithotomy position, and place a vaginal speculum. If collapsing side walls are a problem, use a condom with the tip cut off, the thumb from a very large rubber glove with the tip cut off, or one half of a Penrose drain over the speculum, or use tongue blades or sidewall retractors to improve exposure. 

Step 3

Select a probe that adequately covers the entire lesion and the entire transformation zone. Use only flat-ended or short nipple-tipped probes, not probes with long endocervical extensions, because they cause more cervical stenosis. 

Step 4

Apply a water-soluble lubricant to the probe to act as a thermocouple with the irregular surface of the cervix. 

Step 5

Apply the probe firmly to the cervix, and make sure that it is not touching the side walls of the vagina. Start the freeze by pulling the cryogun trigger on the single-trigger device or pressing the freeze button on the two-button device. 

Step 6

Within a few seconds, the probe will be frozen to the cervix. 

Step 7

Using very light backward pressure on the cryogun, gently draw the cervix forward a few millimeters into the vagina, where probe contact with the side walls is less likely. 

Step 8

A rim of ice should form and grow to a width of at least 5 mm in all quadrants. 
  • PITFALL: Be careful not to allow the cryoprobe to touch the vaginal side wall, because it may stick to and freeze the vagina. The operator may quickly push the vaginal mucosa off the probe with a tongue blade or with a slight twist of the probe. If this is not done quickly, it will become more difficult as the freeze deepens, and more vaginal mucosa will be destroyed. The operator should defrost the probe just enough to release the sidewall and then continue the freeze.

Step 9

Discontinue the freeze. Release the Cryogun trigger or press the defrost button. Wait until the probe visibly defrosts before attempting to disengage it from the cervix. The end of the cervix should appear frozen and white. The cervix should be allowed to regain its pink color (usually in about 5 minutes). 

Step 10

Repeat the freeze sequence as described. The second freeze is usually faster. After the freeze is completed, disengage the probe and remove the speculum. The patient may get up, get dressed, and leave as soon as she is ready. 
  • PITFALL: Fainting and light-headedness are not uncommon. Have the patient rest supine for at least several minutes and then sit up slowly.

    Step 10
    Step 10

Complications

  • Women will experience a heavy discharge for several weeks after cryotherapy. Amino-Cerv cream (one applicator high in the vagina Qhs for 10 days) may be used after therapy in an attempt to decrease the discharge, although this use is not well studied. Cervical eschar debridement does not shorten the length or amount of discharge.

  • Bleeding and infection (rare).

  • Undergoing cryotherapy of the uterine cervix increases the risk that a follow-up colposcopic examination will be inadequate. The squamocolumnar junction has a tendency to migrate deeper into the cervical os, making it difficult to sample the endocervix. This is especially true of older nipple-tipped probes, which are not currently recommended.

  • Development of carcinoma after cryotherapy (failure of therapy).

  • Anaphylactoid reaction to the cold exposure.

  • Theoretical concerns about reduced fertility include the induction of cervical stenosis, a detrimental effect on cervical mucus, cervical incompetence, and tubal dysfunction secondary to ascending infection. No strong clinical evidence supports any of these concerns.

Pediatric Considerations

Because Pap smear screening is not recommended until a patient has been sexually active for 3 years or is 21 years of age, this procedure is not commonly performed in the pediatric population. Also, treatment recommendations are much more conservative in this population. 

Postprocedure Instructions

Instruct the patient to refrain from sexual intercourse, douching, and tampon use for 2 to 4 weeks. A discharge is expected for 3 to 6 weeks, but it may last up to 2 months. The patient should report any significant bleeding or malodorous vaginal discharge. A follow-up Pap smear with or without colposcopy should be scheduled for 6 months later. 
Patients may be followed with Pap smears or colposcopy, or both, every 6 months until two negative exams are obtained. Routine yearly screening may then be resumed, although the patient is at high risk for developing lower genital tract dysplasia for at least 20 years. Any sign of recurrence requires repeat colposcopic examination. 

Coding Information and Supply Sources

ICD-9 Codes

Supplies

Appendix H lists standard gynecologic instruments. Cryotherapy units may be obtained from these suppliers: 

Bibliography

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