Scars should never be obvious when you wear a swimsuit, and only if done in the underarm would they even be barely visible. Scars are kept to a minimum length in my practice, just sufficient to make the pocket. For saline implants this can be as short as 2.5 -3.5 cm. or 1.0-1.5 inches. Incisions are repaired very securely with slowly absorbing sutures so there is no worry about the incision coming open in the healing process, and there are no sutures to remove.
In the past, a gel implant required a larger incision than a saline implant. The saline implant comes deflated and can be placed through a 2.5-3.5 cm incision. However, a gel implant comes fully filled from the manufacturer, so one must imagine the full size of the new breast fitting through the incision. The larger the implant, the larger is the required incision. In fact in the past, implants in the 400 cc or larger range required incisions of 4.5-5.25 cm or larger. The reason the incision had to be longer is because one cannot force an implant through an incision that is too small. In the first place, the implant will simply not go through the incision, and secondly, the manipulation required to gradually introduce the implant could traumatize the implant shell, possibly leading to early implant failure. The usual procedure is to make an incision of adequate length, and then if there is any significant resistance at the time of insertion, to stop, remove the implant and slightly lengthen the incision.
For patients requesting gel implants, I always now give them the option of using a Keller Funnel, to get the smallest possible incision. This innovation in breast augmentation surgery allows placement of gel implants through incisions that are often as small as the incision required for saline implants. This depends on the implant size, but since most women have implants of 400 cc or smaller, most women can have their implants placed through an incision length of 3.5-3.75 cm, the same as saline implants. You can read more about the Keller Funnel at their website.
The result is a shorter scar and minimal handling or trauma to the implant regardless of incision location. The incision location is an individualized decision made in consultation with the patient based on her anatomy, location preference and consideration of trade-offs and advantages with each incisional approach. Since I offer a choice of all incision locations, patients make their own choice after consideration of the pros and cons associated with each.