Can saline implants be partially deflated for purpose of wanting smaller breasts instead of an explant?

It sounds like a good compromise, but unfortunately it is not possible.  The valve of the implant closes once the implants are filled during initial surgery.  Any manipulation of this valve would have to be done surgically and would likely damage the implant/valve.  

Thank you for a great question.  Saline implants do have a valve but it is sealed when the tube is removed after  filling the implant during a surgery.  The only way to remove some fluid from the implant, would be to poke a hole in the implant with a needle. Once this is done, the implant will slowly deflate which could happen over several days.

Sakine breast implants have a valve and opening in the tip of the implant through which we fill them. Once they are out under the breast the fill tube is removed and the opening is pushed close. To change size you would have to have surgery to go through the breast to the valve, open it and either add or remove saline. This cannot done by putting a needle through the skin into theimsvt which would cause gradual deflation of the implant. Be aware that removing a significant amount of saline from the implant or underfilling them would result in implants creasing and rippling as well as to a much higher rate of early shell weakening and implant rupture. 

Puncturing saline-filled implants generally eventually results in complete deflation and also voids the warranty on the implants. Saline-filled implants also are intended to be filled to their rated volume and no more than about 10% additional volume. Over or under-filling them results in problems like rippling and palpable creases as well as works against their long term integrity. The simplest way to downsize implants (assuming everything else is satisfactory) is to do a simple exchange through an inframammary crease incision where the forward volume of the implant is reduced by decreasing it's projection but it's still filled properly. The horizontal (diameter) width of the implant cannot be reduced much without problems related to the base width of the breast and capsule. 

Good thinking but unfortunately it is not possible.  Usually a needle is placed percutaneously through the wall of the implant and leads to complete deflation within a day or two.  A small surgical procedure to open the valve and remove some of the fluid is possible but nearly certain to result in rippling and waviness of an underinflated implant.  It is also not recommended after six months by the manufacturer due to the risk of future valve failure.  Thanks for your question and best wishes,Jon A Perlman M.D., FACSDiplomate, American Board of Plastic SurgeryMember, American Society for Aesthetic Plastic Surgery (ASAPS)Beverly Hills, California