incomplete tumor destruction occurs, treament of the postoperative recurrence may be required.
Expected outcome
Incomplete tumor destruction likely results in recurrence postoperatively.
"Run‐off " of Cryogen
Definition
When the cryogen runs down from the site that should be frozen
Risk factors
Use of a cryosurgical device that sprays liquid nitrogen
Fast freezing by pouring liquid nitrogen onto the tissues
Pathogenesis
Application of cryogen by spray is less precise than by probes and some technical experience is required to apply cryogen safely [21]. When the sprayed liquid nitrogen comes into contact with the tissue, it evaporates. However, when too much liquid nitrogen is applied at any one time, it does not evaporate immediately and runs off the skin causing inadvertent frost lesions. This complication is more likely to occur when treating large lesions that require the application of more cryogen in order to obtain rapid freezing of the entire lesion.
When liquid nitrogen is poured onto the tissues without a device to keep it in place, run‐off is unavoidable.
The size and depth of the frostbite injury that occurs following run‐off depends on the amount that has been spilled. However, full thickness skin lesions are unlikely to occur.
Diagnosis
Evident during the procedure as the cryogen runs away from the desired area
Prevention
For spraying instruments, “cups” can be used to confine the cryogen to the lesion and prevent run‐off. The use of cups is essential when pouring liquid nitrogen directly onto the lesion. Cups are commercially available [20] or can be custom‐made from PVC‐tubing or any other material (Figure 11.1). Different sizes should be used, depending on the lesion to be treated. The use of a contact gel is advised to ensure that the entire cup fits well on the surrounding skin and sticks to the skin as soon as the liquid nitrogen is applied.
An alternative to the use of cups for spraying instruments is to pack the surrounding area with vaseline‐impregnated sponges or styrofoam to prevent run‐off [16]. This is more difficult compared to the use of cups as they often do not seal perfectly to the surrounding normal tissue [14]. Open cell foams and gauze swabs should be avoided as they soak up the cryogen and become themselves a cold sink producing damage which it was intended to prevent [13].
Figure 11.1 A self‐made PVC cup is used to confine the sprayed liquid nitrogen to the lesion. Thermocouple needles (arrowheads) are placed in the tissue to be frozen and the underlying healthy tissue and a gel is used to ensure good sealing between the cup and the surrounding healthy skin.
Source: Ann Martens.
Treatment
When run‐off of cryogen is identified during surgery, the frozen skin should be warmed up as quickly as possible (e.g. with a sponge soaked in warm water). Rubbing is contraindicated as this worsens the skin damage. Topical aloe vera cream or gel (antithromboxane) applied immediately after injury and in the follow‐up period can help prevent local thrombosis and ischemia [22].
Expected outcome
Most injuries are superficial and will heal uneventfully. In case of deep injury, hypo‐ or leukotrichia can result.
Early Postoperative Complications
Bleeding after Cryosurgery
Definition
Hemorrhage from the cryoablation site that is evident in the first 2–3 hours after surgery
Risk factors
Tumors that require debulking to the level of the surrounding skin before freezing
Tumors from which a biopsy is taken prior to freezing
Tumors located over a large superficial vein [14]
Pathogenesis
Limited bleeding after cryosurgery is normal in tumors that have been debulked or when a biopsy has been taken, even if good hemostasis was obtaind prior to freezing. Bleeding results from vasodilation during the thawing phase. It is commonly self‐limiting, but can become objectionable to the owners [20].
Excessive postoperative bleeding is a rare complication which could occur as a result of necrosis of the wall of an intact vessel that was frozen together with the tumor (e.g. saphenous vein for sarcoids on the inner aspect of the thigh). The author has not experienced this complication yet, most likely because coagulation necrosis of the frozen tissue also results in vessel thrombosis before rupture of the wall would occur.
Diagnosis
Obvious hemorrhage from the surgical site
Prevention
When tumors are debulked or a preoperative biopsy is taken, care should be taken to achieve good hemostasis (e.g. using radiofrequency electrocoagulation).
When treating lesions are resting directly over a large superficial vein, the latter can be ligated proximally and distally to prevent hemorrhage when the tissue sloughs [14].
Contact probes should be allowed to detach spontaneously from the tissue during the thawing phase. Avulsion of the probe can precipitate unnecessary bleeding because of tissue tearing [1].
A pressure bandage can be applied over the site for the first 24 hours to prevent hemorrhage [14].
Treatment
Management of postoperative bleeding consists in providing hemostasis, either by clamping and/or suturing the vessel or by applying a pressure bandage.
Expected outcome
The prognosis is good because postoperative bleeding after cryosurgery is never life‐threatening.
