TUBA (Trans-umbilical breast augmentation) was invented by Dr. Gerald W. Johnson (of Houston, TX), and first performed it in October of 1991. Unfortunately, there are few surgeons employing this technique because the vast majority of them are not educated on how to perform it. With this method, the implants can be placed over the muscle, or in the sub-muscular position.
The incision is made at the rim of the navel. Then, using an endoscope (a lighted camera), a tunnel is made through the subcutaneous fat, just beneath the skin, to the loose tissue behind the breast. (Most surgeons use a temporary expander to form the pocket, but I have heard of one surgeon who does not use this method, and just uses the breast implant as the "expander"). Once the pocket has been made, the implant is rolled up, inserted through the incision, and worked up to the breast. Once placed in the pocket, the sterile saline solution is added through the fill tube. When the desired fill amount and/or look is achieved, the fill tube is removed, closing and sealing the internal valve. The surgeon usually carefully examines everything with the endoscope, once the implant is in place. If everything goes accordingly, the endoscope is removed, and the incision is sutured.
The incision scar is very small, and practically undetectable. The skin on the abdomen has more elasticity than the skin on the breast, or under the arm, hence, the smaller scar.
Because the TUBA method is less invasive than other methods, it is said to have a shorter recovery period, as well as less post-op discomfort, due to less trauma of the tissues. However, pain and discomfort from stretching skin and/or muscles will still be present, regardless of the incision that is used. Another point to consider is that sometimes, "v" tracks are permanent on the stomach. This is from the endoscope being pushed up under the skin. Though "v" tracks aren't common, they can and do happen.
There are disadvantages to all incisions, and TUBA is no exception. First, it can be somewhat difficult to find a surgeon that is skilled and experienced with this procedure. If you want partial sub-muscular placement, you will have an even more difficult time. If there are problems with the placement of the implants via the navel incision, it's likely that another incision will need to be used, commonly the areola or crease incision. When using the TUBA method, the surgeon will be working quite a distance from the breast, which means less control. If this is the procedure you desire, finding a qualified surgeon is strongly advised.
Lastly, using the TUBA method will not void your implant warranty.
All incisions have their advantages and disadvantages. Incision placement depends on what you, as an individual, prefer, as well as whether or not you can find a doctor experienced in using the type of incision you desire.