The so-called “urethral warmer” is an additional thermal element, typically applied in prostate cryosurgery to reduce destruction to the urethra, and thereby prevent post-cryosurgery complications (the urethra extends nearly to the center of the prostate). The clinical and technological complications of a cryoprocedure with such a large number of cryoprobes may not yet be fully appreciated. Furthermore, inserting a large number of cryoprobes into a small target region (i.e., small organ) may cause additional injury to surrounding healthy tissue.
Naturally, the application of a large number of cryoprobes is cause for debate over cost-effectiveness. If effectively localized, one of the potential benefits of a large number of miniaturized cryoprobes is superior control over the freezing process. In an effort to gain better control over the cryosurgical procedure, the number of cryoprobes has been increased so that more than a dozen cryoprobes can be applied simultaneously. With recent technological developments, the diameter of the cryoprobe has decreased dramatically (Endocare, Inc., CA Galil-Medical, Inc., Israel). To overcome this difficulty, five and six (Erbe Elektromedizin GmbH, Germany) minimally-invasive cryoprobe arrangements were suggested during the early 1990's, based on liquid nitrogen cooling. The minimally-invasive approach created a new level of difficulty in cryosurgery planning in which a pre-defined 3D-shaped tissue must be treated while preserving the surrounding tissues. Prostate cryosurgery was the first minimally-invasive cryosurgical procedure to pass from the experimental stage to routine surgical treatment. The cooling effect creates a frozen region around the tip of the cryoprobe, typically in the shape of an elongated ellipsoid, for a single operated cryoprobe. Regardless of the cooling technique, the cooling fluid is not brought in direct contact with the tissue, but displaced to the surroundings.
The cooling effect is created near the tip of the cryoprobe, using either liquid nitrogen boiling, or the Joule-Thomson cooling effect (the cooling effect associated with sudden change in pressure of gas flowing through a nozzle). Minimally-invasive cryosurgery is typically performed by means of cryoprobes in the shape of long hypodermic needles, with a sharp pointed tip. Cryosurgery has been used to treat cancerous tissues in a large variety of clinical applications, such as skin, hemorrhoids, brain, bone, kidney, liver, breast, and prostate cancers it has great potential as an alternative to conventional surgery, with minimal damage to healthy surrounding tissues. Cryosurgery is the destruction of undesired biological tissues by freezing.
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