Can transaxillary breast augmentation only be done once?

Saline, but not silicone breast implants can be exchanged through a trans-axillary approach. The disadvantage of the axillary approach is that the breast pocket can not be readjusted well. 

I do like the hidden scar, but once a gel implant is placed through the incision, it is difficult or impossible to remove it.  I don not like this because I feel I have less control over the final shape.  The IMF incision is soooo much nicer and I think there is a reason so many experienced surgeons prefer it.Future surgeries will need to be done through another incision in almost all cases. 

Dear Glorious8766,
I tend to prefer the periareolar incision because its the most well hidden. There is a natural border between the areola and the rest of the breast skin the hides the incision extremely well. You have to be completely naked to see it vs other incisions like transaxillary and inframammary are visible in clothing such as sleeveless shirts and bikini tops when extending your arms up. I've also noticed increased rates of bottoming out with inframmary incisions that is not reported. Transaxillary implants are always wide in appearance because the surgeon is not able to dissect medially enough to provide better cleavage. Ultimately, I can perform any of the incisions but I recommend the periareolar. There is no difference in sensation because the nerves that control nipple sensation come in laterally from the back and injury to them occurs when surgeons dissect to far laterally which is why transaxillary incisions have the highest nipple sensation disruption. There is no difference in breast feeding ability. One study did show a slight increase in capsular contracture with use of periareolar but that study was small and did not incorporate modern techniques such as below muscle placement, keller funnel usage and triple antibiotic irrigation. 
Daniel Barrett, MD
Certified, American Board of Plastic Surgery
Member, American Society of Plastic Surgery
Member, American Society of Aesthetic Plastic Surgery

I would undergo the procedure with the incision that your plastic surgeon feels most comfortable using. I have been using the IMF incision for 15 years and patients are quite pleased with the outcomes. IMF incisions also have been shown to have the lowest capsular contracture rates compared to periareolar and axillary incisions. Especially for  revision, I believe that an IMF incision will offer your surgeon an improved access to your pocket, and if refinements need to be made of your pocket, I feel that this is the best approach. Don't stress about the scar as it will be hidden in the breast crease. I would stress more about a less than perfect result performed through an incision that is much more difficult with higher capsular contracture rates. Good luck!

Yes, it is possible to have the revisionary breast operation done through the transaxillary appproach IF significant adjustment of the breast implant capsules or  pockets is not necessary.  Your plastic surgeon, assuming he/she has significant experience with this approach, will be your best resource when it comes to more specific thoughts.
 Personally, in my practice, I prefer the infraareolar incision for most revisionary breast operations. I find that this incisional approach allows me to make necessary adjustments of the breast implant pockets;  I find that skillful manipulation of breast implant capsules is frequently necessary to achieve the best aesthetic outcome possible.
 Best wishes.