What Is Symmastia? When Breasts Merge Into One

Medically Reviewed by Traci C. Johnson, MD on March 17, 2023
3 min read

Symmastia is when your breasts grow together, with little or no cleavage between them. Instead, there’s a web of skin, fat, and tissue across the cleavage area. There are different degrees of this condition. Sometimes the lack of cleavage is less noticeable.

That depends on which type you have.

Congenital symmastia. You’re born with this condition. It’s rare, and no one knows exactly what causes it.

Acquired or iatrogenic. This type is still rare, but more common than the congenital kind. It’s usually a complication of breast reconstruction or augmentation surgery. It can happen when breast implants are too close together, especially if they’re too wide for you. There’s a higher risk if you’ve had several breast reconstruction surgeries already.

Sometimes it results from an accidental cut during the implant process. Because there’s no natural space in your breast to hold an implant, surgeons have to create a pocket for it. They’ll probably use your own tissue from another body part. If that won’t work, they could try animal tissue, usually from a pig. The pocket should be the same size or slightly larger than the implant. If it’s too big and the doctor makes cuts the wrong way, the two pockets can join together to form one large open space.

Symmastia doesn’t usually cause any serious health problems. You may decide you want to fix it for cosmetic reasons, though. Many surgeries for both types involve reattaching skin to the breastbone to redefine the cleavage. Your surgeon may also have to create new pockets to hold implants or replace them with narrower ones.

It’s possible to treat the congenital kind, but your surgeon has to fix both the structure and size of your breasts. Experts don’t agree on which type of surgery is best. Different operations may work better for different people. In general, you shouldn’t have surgery until your breasts have finished growing.

One technique that has worked well for this type uses a three-step procedure. The first step uses liposuction or surgery to take out a small amount of breast tissue. Then, the surgeon attaches the skin at the cleavage area to the breastbone. Finally, they compress the area to help the skin and chest wall heal. You’ll also need to wear a compression bra for a while. Possible complications include scarring and breasts that aren’t the same size or shape.

If you decide to have surgery, get a second opinion from another surgeon before you commit. When you pick a surgeon, make sure you choose one who’s already done a lot of similar procedures.

If you want cosmetic breast surgery, there are steps you and your surgeon can take to make sure this condition doesn’t happen to you. Discuss the type and size of implant and if it’s suited to your body. Also make sure that your surgeon has done many similar surgeries before. This will lower the chances that they’ll make any mistakes.