What is the procedure for treating warts with liquid nitrogen (LN) cryotherapy?

Liquid Nitrogen Cryotherapy for Wart Treatment

Pre-Treatment Preparation

Before applying liquid nitrogen, pare down or debride heavily keratinized warts to improve treatment efficacy. 1

• Ensure the patient can see and reach the warts easily for proper assessment and follow-up monitoring 2
• Exclude cervical dysplasia before treating any exophytic cervical warts in women 2
• Assess for contraindications including poor circulation to extremities, cold intolerance disorders (Raynaud's disease, cryoglobulinemia, cold urticaria), and be cautious in patients with diabetes or peripheral vascular disease due to delayed healing risk 1

Application Technique

Apply liquid nitrogen using a spray gun method, delivering a sustained 10-second freeze for optimal efficacy. 3

• The traditional "freeze until halo of ice" method achieves only 39% cure rates, while a sustained 10-second freeze achieves 64% cure rates after five treatments 3
• Consider topical or injected local anesthesia if treating large areas or multiple warts 4
• Proper training is essential—both over-treatment and under-treatment reduce efficacy and increase complications 4

Treatment Schedule and Duration

Repeat treatments every 1-2 weeks for optimal results. 1, 4

• Plan for 3-4 months of treatment (approximately 6 sessions maximum) 1
• If no substantial improvement after three treatments, or no complete clearance after six treatments, switch to an alternative modality 4
• Common warts respond better to cryotherapy (49% cure rate) than plantar warts, which show no significant advantage over salicylic acid or watchful waiting 5

Anatomical Considerations and Restrictions

Never use cryoprobes in the vagina due to perforation and fistula formation risk. 2, 1, 4

• Vaginal warts: Use liquid nitrogen spray only, avoid cryoprobes entirely 2, 1, 4
• Urethral meatus warts: Liquid nitrogen is appropriate; ensure treatment area is dry before contact with normal mucosa 2, 4
• Anal warts: Liquid nitrogen is suitable for external lesions, but refer rectal mucosal warts to a specialist 2, 4
• Oral warts: Liquid nitrogen is an appropriate first-line option 2, 4

Expected Side Effects and Management

Warn all patients that pain, blistering, and permanent skin discoloration are common and expected. 1, 4, 3

• Pain and blistering occur significantly more with 10-second freezes (64% of patients) compared to traditional shorter freezes (44% of patients), but efficacy justifies this increased morbidity 3
• Hypopigmentation or hyperpigmentation is common, especially in darker skin tones 1, 4
• Scarring can occur if treatment extends too deeply into the dermis 1
• Nerve damage is rare but possible in areas with superficial nerves 1

Post-Treatment Instructions

Instruct patients to keep the area clean and dry, allowing the scab to fall off naturally within 1-2 weeks. 1

• Washing is permitted but avoid scrubbing the treated area 1
• Do not pick at or remove the scab prematurely 1
• Return for follow-up in 2-4 weeks for assessment and possible retreatment 1
• Contact provider immediately if signs of infection develop (increasing pain, warmth, redness, swelling, or discharge) 1

Documentation Requirements

Document the dose, duration, number of freeze cycles, and obtain verbal consent for each treatment session. 1

• Provide patients with a written information leaflet about cryotherapy 1
• Evaluate the risk-benefit ratio throughout the treatment course to avoid overtreatment 4

Efficacy and Recurrence

Cryotherapy achieves 63-88% efficacy for common warts, with recurrence rates of 21-39%. 1

• Most recurrences occur within the first 3 months after treatment 1, 4
• After visible warts clear, follow-up is not mandatory, but patients should monitor for recurrences 4
• Warts on moist mucosal surfaces respond better than heavily keratinized lesions 2, 4

Alternative Options When Cryotherapy Fails or Is Contraindicated

If cryotherapy is not tolerated or contraindicated, use salicylic acid 15-40% as first-line alternative. 1

• Other alternatives include surgical removal, electrocautery, laser therapy, or immunotherapy 1
• For genital warts specifically, trichloroacetic acid 80-90% can be used, though it is less effective than cryotherapy for common warts 2, 6

Special Population Considerations

Cryotherapy is generally considered safer than chemical alternatives during pregnancy, though safety data is limited. 1

• Immunosuppressed patients can receive standard cryotherapy to reduce wart size and functional/cosmetic problems 1
• Annual cytologic screening is recommended for women with genital warts, but genital warts alone are not an indication for colposcopy 2