Fat is withdrawn from the patient in one of three ways: with a syringe that has a large-bore needle or with a liposuction cannula.
The fat is prepared according to the practitioner’s preferred method and then injected into the patient’s recipient site. The preparation process clears the donor fat of blood, pain killers and other unwanted ingredients that could cause infections or other undesirable side effects.
To obtain viable fat, the needle withdrawing the fat can’t be too narrow, the liposuction cannula can’t have too strong a vacuum pressure and the centrifuge used to clear debris from the donated tissue can’t spin too rapidly. The vacuum pressure on the liposuction machine should not be higher than 700 mmHg.
A few doctors excise, or cut, small strips of fat from the body and then place, rather than inject, the tissue in the recipient site, using additional small incisions.
Other uses and applications continue to develop as surgeons work with, and learn more about, fat transfer. Some of the most current and developing applications include:
- Cheek and chin implants
- Repair of inverted nipples
- Increasing the girth of the penis
Depending on the surgeon, the patient and several other factors, the body is reported to reabsorb anywhere from 20 to 95 percent of transferred fat.
In most applications, fat injections are laid down through several different layers of skin and muscle to provide a better chance for the fat cells to find a nearby blood supply. Because some fat is always absorbed, most physicians inject somewhere around 30 percent too much. Physicians have learned the best donor areas are found in:
- The lower stomach
- The inner thighs
- The inner knees