Symmastia is a condition where the breasts appear to merge together across the breastbone, eliminating the natural space between them. Sometimes called “breadloafing” or “uniboob,” it happens when breast implants shift too far toward the center of the chest, creating a bridged or single-breasted appearance. It can develop immediately after breast augmentation or slowly over weeks, months, or even years.
What Symmastia Looks Like
The hallmark sign is a loss of the inner cleavage fold. Instead of two distinct breasts separated by a defined gap over the sternum, the skin lifts away from the breastbone and stretches across the midline like a tent. If you press the skin in the center of your chest and it moves around or feels squishy underneath rather than firmly attached to bone, that’s a strong indicator.
The visual change is most obvious when wearing a tight bra or in certain body positions, where the skin over the sternum looks pulled taut. Beyond appearance, many women report localized pain, a feeling of pressure in the chest, or discomfort when moving their arms. In more severe cases, the compressed tissue can become inflamed or irritated, and the implants may feel unstable or shift easily from side to side.
Why It Happens
Symmastia after augmentation is almost always a surgical complication. The most common cause is over-dissection of the tissue along the inner edge of the implant pocket. During augmentation, the surgeon creates a space for the implant either above or below the chest muscle. If that space is carved too aggressively toward the midline, it can detach the skin and tissue from the breastbone, allowing the implant to drift inward. When both pockets are over-dissected, the two implant spaces can actually connect across the sternum.
In submuscular placement (where the implant sits beneath the chest muscle), there’s an additional mechanism at play. The pectoralis muscle’s attachment along the sternum can be divided too aggressively, changing the way force is distributed across the chest wall. This altered tension can gradually push the implants toward each other over time, even if they seemed well-positioned right after surgery.
Implant selection plays a significant role too. Implants that are too large or too wide for the patient’s chest create outward pressure that the surrounding tissue can’t contain. In one case series, 40% of patients who developed symmastia had implants that were excessively large or too wide for their ribcage. Patients with existing chest wall irregularities, like a sunken breastbone (pectus excavatum), face higher risk as well, since the anatomy already makes midline attachment weaker.
Congenital vs. Acquired Symmastia
A rare form of symmastia exists from birth. In congenital cases, the skin in the center of the chest simply never adhered to the breastbone the way it normally would. Fatty tissue sits between the skin and the bone, preventing attachment. This is an uncommon anatomical variant and is unrelated to implants.
The far more common version is acquired (iatrogenic) symmastia, which results from breast augmentation or reconstruction. The distinction matters because the two types are treated differently, and acquired symmastia is generally easier to correct.
How It’s Diagnosed
Diagnosis is primarily clinical. A plastic surgeon evaluates the appearance of the breasts, the position of the implants, and the quality of the surrounding tissue through a physical exam. In most cases, no imaging is needed. Occasionally, an ultrasound or MRI is ordered to assess exactly where the implants sit or to check for related complications like capsular contracture, but this isn’t routine.
Nonsurgical Options for Early Cases
If symmastia appears soon after the initial augmentation, before tissue has fully healed into its new position, there’s sometimes a window for conservative treatment. A specialized compression bra designed to separate the breasts and press the cleavage skin back against the breastbone can help guide healing. This works by maintaining steady inward pressure on each implant while encouraging the midline tissue to re-adhere. However, this approach is only viable in mild, early cases. Once the tissue has healed in a displaced position, surgery is the only reliable fix.
How Surgical Correction Works
Revision surgery for symmastia focuses on rebuilding the inner boundary of each implant pocket so the implants can no longer drift toward the midline. The most common technique is called capsulorrhaphy, where the surgeon places internal sutures to close off the over-dissected medial portion of the pocket, effectively creating a tighter, more defined space for each implant.
In some cases, the surgeon will switch the implant from a submuscular position to one above the muscle, then reattach the chest muscle to its original position along the sternum. This eliminates the prior pocket entirely, preventing the implant from migrating back into it. One study of 36 patients who underwent this conversion found a 100% success rate for correcting implant malposition and symmastia at an average follow-up of about 20 months. A separate study of 23 patients using a similar internal repair technique reported the same: all corrections held at nearly two years of follow-up.
For more challenging cases, surgeons may reinforce the repair with a biologic mesh, a sheet of processed tissue that acts as a physical barrier along the inner edge of the pocket. The mesh is secured to the tissue along the sternum on one side and the breast tissue on the other, creating a firm wall that blocks medial migration. This has become a well-established tool in breast reconstruction and provides a particularly strong, defined boundary when the patient’s own tissue is too thin or weakened to hold sutures alone.
Revision surgery also frequently involves downsizing the implants. If the original implants were too wide for the patient’s frame, even a perfect pocket repair may fail under the same outward pressure. Choosing an implant whose base width matches the chest measurements is one of the most important factors in preventing recurrence.
Recovery After Revision
Recovery from symmastia repair is similar to the original augmentation in many ways, though the tissue manipulation can be more involved. You can expect swelling, bruising, and restricted arm movement for several weeks. Most revision surgeons use a compression garment or specialized bra to maintain pressure over the midline during healing, since keeping the skin adherent to the sternum while the internal sutures set is critical to the result.
Full results typically take several months to settle as swelling resolves and tissues heal into their new position. Surgeons generally want to see stability at the one-year mark before considering the correction complete, though published studies tracking outcomes at 20 to 22 months show durable results with modern techniques.
Prevention During Initial Augmentation
The best treatment for symmastia is avoiding it in the first place. Three factors matter most: implant sizing, surgical technique, and anatomy assessment. Implants should be selected based on the patient’s actual chest wall measurements, not just a desired cup size. The base width of the implant needs to fit within the breast footprint without crowding the midline.
During surgery, careful and conservative dissection of the inner pocket preserves the thin but dense layer of tissue (fascia) that anchors the skin to the sternum. Gentle technique under direct visualization minimizes the risk of releasing too much of the chest muscle’s sternal attachment. Patients with narrow sternums, previous breast surgeries, or chest wall deformities warrant extra caution, as their anatomy already predisposes them to medial implant displacement.