Anatomical to Round implants - will staying with the same cc's look bigger or smaller?

The round implants of the same volume will fit your body and clothes the same. In controlled clinical trials expert plastic surgeons could not discern the difference from anatomical vs round implants. Sounds like you are making a good choice. Good luck....

The 153 was taken off the market around 2005 or so because it had a very high rupture rate.  The gel was the standard relatively soft gel and the design achieved a quasi-anatomic shape by virtue of placing a second, smaller shell in the lower pole and fusing it to the outer shell.  This created a point of stress and the implant had a high shell failure rate.  That was entirely predictable and it was simply an ill-conceived design.  Anyhow, there was a recall of sorts and I think the company provided free implants, but I don't recall the details.  And if they did it may still not be enforced, though if you complain enough they might.   McGhan was acquired by Inamed which was acquired by Allergan.  It's worth calling Allergan Customer Service to find out.Apropos of your question, that implant tended to collapse and lose height so there probably will be little difference between that implant and a round implant.  Any comparisons to newer anatomic implants such as the Allergan 410 do not apply.

Thank you for your question.There is no accurate/reliable/predictable way to generalize whether the anatomical implants and round implants will give you a certain "look".  Best to specifically communicate your goals.
Ultimately,  careful selection of your plastic surgeon and careful communication of your goals (in my practice I prefer the use of goal pictures, direct examination/communication in front of a full-length mirror, and computer imaging) will be critical. Keep in mind as you are thinking about your goals that sometimes adjustment of the breast implant pockets (capsule adjustments) may be necessary to achieve the outcome you are looking for.
Generally speaking, the best online advice I can give to ladies who are considering revisionary breast augmentation surgery is:
1. Concentrate on choosing your plastic surgeon carefully. Concentrate on appropriate training, certification, and the ability of the plastic surgeon to achieve the results you are looking for. ***Ask to see lots of examples of his/her work.
2. Have a full discussion and communication regarding your desired goals with your plastic surgeon. This communication will be critical in determining breast implant size/type/profile will most likely help achieve your goals. 
In my practice, the use of photographs of “goal” pictures (and breasts that are too big or too small) is very helpful. I have found that the use of words such as “natural” or "up a cup size”  etc means different things to different people and therefore prove unhelpful.
Also, as you know, cup size varies depending on who makes the bra; therefore, discussing desired cup size may also be inaccurate. 
3. Once you feel you have communicated your goals clearly, allow your chosen plastic surgeon to work with you in determining the best plan to achieve your goals.
I hope this, and the attached link (dedicated to revisionary breast augmentation surgery concerns), helps. Best wishes.

should have minimal change in volume but depending on your anatomy, may look a little fuller in the upper pole.  I wouldn't anticipate huge differences but why is your motivation for going to round implants after the new technology anatomic implants?

In general, round implants will have slightly more upper pole fullness, especially in the first few months to years, when compared to anatomic implants. The distribution of volume is different in a round implant so while you may see more upper pole fullness, you may see a corresponding slight decrease in the lower pole if you are going with the switch to round. Why are you contemplating a switch? Is it the age of your implants, capsular contracture, deflation, sagging of the breasts or some other issue? It will also make a little bit of a difference whether you select saline vs. silicone. In my experience, a saline implant of X cc's looks about 5% larger than a silicone implant of X cc's once settling has happened. I don't have a great physiologic or scientific answer for why this is, but I usually "upsize" a few cc's with silicone to get the same projection that a saline implant or saline sizer on the operating table might indicate. Hope this helps!

Thank you for the question and volume is volume so cc for cc should be the same though your present implants may be rupturedDr Corbin

I would expect the differences to be minor (unless your anatomic implants rotated).  A recent study compared each implant placed (temporarily during the surgery only) on each side and neither was felt to be aesthetically preferable.  My routine is to use round smooth implants of a  mid or mid+ profile for the majority of my patients.  You'll get useful information from the attached video link.  
Jon A Perlman MD FACS 

Extreme Makeover Surgeon ABC TV

Certified, American Board of Plastic Surgery 

Best of Los Angeles Award 2015, 2016 

Beverly Hills, Ca 
 Enjoy your results.

Generally, when switching from an anatomically shaped implant to around implant of equal volume, with the absence of any capsular contracture, there may be slightly less upper pole fullness than the taller anatomically shaped implant. However, the projection of the round implant may be more.Comparison to a 410 are irrelevant. Overall unless you have very thin overlying tissues, these differences should be subtle. Hope that's helpful.

Going from a McGhan anatomical implant to the same size round implant may give you slightly more fullness at the top, but after so many years with your implants I doubt you'll see a great deal of difference.