Reference Manual - IARC Screening Group

Treatment and FollowupNote: When CO 2 is used as the coolant, it is important to use this“freeze-clear-freeze technique” during the entire freeze time. If it isdone correctly, this technique will not adversely affect the freezing ofcervical tissue, but will prevent the cryotherapy unit from becomingclogged with ice during the procedure. If a provider waits for morethan 15 seconds to press the defrost trigger, the unit may becomeclogged later during the procedure. Puffs of white gas or small piecesof ice may come out of the exhaust port; this means that the unit isremoving ice from the hose. If the unit becomes clogged, follow stepsfor clearing the ice (see Appendix D, page D-5).Step 11 After 3 minutes of freezing, the cryotip will be attached to thecervix by the ice ball. Do not pull the cryotip off. Wait for it todefrost and detach itself from the cervix. (This usually takesless than 30 seconds.)Step 12 Wait 5 minutes and repeat the freezing procedure using thefreeze-clear-freeze technique. It may be necessary to increasethe freeze time up to 5 minutes if the ice ball is not 4 mmbeyond the lateral edges of the probe (Figure 7-6).Figure 7-6. Freezing Process with Cryotherapy UnitCervical Cancer Prevention Guidelines for Low-Resource Settings 7-17