Fat Freezing/ coolsculpting. Is this frostbite? (Photo)
Doctor Answers 4
Post Treatment Reaction
Unusual swelling from Cool Sculpting
Unusual and Inexplicable Swelling after CoolSculpting
Let's assume that what we are seeing is true to reality. The affected area is very well defined and seems to conform to the size and shape of the CoolFit applicator. Several possibilities come to mind: 1) the patient has some type of cold-induced underlying disorder, such as cryoglobulinemia, or has circulating cold-agglutins; 2) there was bleeding under or witihin the treated area and there is now a large hematoma, perhaps due to some underlying bleeding tendency she might have; or 3) the gel pad shifted or somehow was not applied as intended. The gel pad acts as a heat sink, allowing the heat that is being drawn from the body into the device to do so evenly over the treatment area. It prevents overchilling of any one part of the skin touching the gel pad, which is between the skin and the cold plates. Your sister would probably remember this being applied, as it feels shockingly cool and wet for the first few seconds after it is placed on the skin. It is put on the skin before the applicator.
There is no frostbite with CoolSculpting, because, contrary to popular opinion, the fat is not chilled to the freezing point, but only close to the freezing point of fat. Think of a stick of butter: when at body temperature, it is runny, and when you chill it (without freezing) it becomes firm. It does not need to freeze to be firm. Fat cells do not need to be frozen to look like the "stick of butter" everyone talks about when the applicator is removed. Nor do they need to be frozen to be injured enough to be shifted into a different cellular state called "apoptosis," or programmed cell death. In other words, they are injured just enough, and no more, such that each affected cell begins to slowly shut down its functions, but it takes time for it to melt away and "die." [Apoptosis is actually a natural process by which cells can die and be replaced by healthier cells that takes place every day in your body. Cryolypolysis just nudges a lot of the fat cells into this state all at once.] Freezing the cells would be undesirable, because too many cells would be dying all at once, and the inflammation could be extreme. And the skin is much farther away from freezing than fat, since its freezing temperature is lower than that of fat, so it should not have frostbite. In any case, in my experience this does not look at all like frostbite.
Having said all of that (probably much more than you bargained for!), this is no substitution for a physical exam. A detailed history and a doctor's hands on is often necessary to understand what is happening. And my thoughts are only postulates and no substitution for proper face-to-face evaluation by a physician. I am merely sharing my experience, and this is not something I have seen.