Symmastia (Uniboob): Causes, Correction Surgery and Recovery

Symmastia — sometimes called “uniboob” or “breadloafing” — is a condition that affects the natural appearance of the breasts, in which the tissue or implants cross over the breastbone and remove the natural gap between the breasts. Instead of a defined cleavage, the breasts look joined together in the centre of the chest, creating the appearance of a single, merged breast mound. Although uncommon, it can be a genuinely distressing complication, particularly when it follows a breast augmentation that a woman had looked forward to. The good news is that symmastia is correctable: with careful surgical planning by an experienced revision surgeon, the natural separation between the breasts can be re-established.

This guide explains exactly what symmastia is, how to tell it apart from a naturally close cleavage or a sports bra “uniboob”, what causes it, the different types, how it’s corrected, what recovery involves, and — importantly — what to check before having the repair. At Centre for Surgery in London, symmastia correction is performed by GMC-registered plastic surgeons who specialise in complex breast implant revision, at our CQC-regulated Baker Street hospital, rated “Good” overall by the Care Quality Commission (CQC). Symmastia is one of several implant complications covered in our broader guide to common breast implant problems.

What Is Symmastia? Symmastia Breasts and the “Uniboob” Explained

The breasts normally sit on either side of the sternum (breastbone), separated by skin, connective tissue, and the underlying bone. This midline boundary is what defines cleavage and creates the space that allows bras and clothing to sit naturally against the chest. In symmastia, this division is disrupted. The breast tissue, skin, or implant pocket extends too far into the middle of the chest, so the visible gap disappears and the soft tissue lifts away from the sternum, forming a web or bridge across the midline.

The term itself comes from the Greek — literally “joined breasts.” You may also see it referred to informally as “uniboob,” “kissing implants,” “synmastia,” or “breadloafing,” all describing the same loss of central separation. Whatever the name, the defining feature is the same: the natural cleavage gap has been lost, and the breasts appear to run together across the centre of the chest.

Symmastia is uncommon, but when it appears it causes both cosmetic concerns and practical difficulties. Many women find it hard to wear bras comfortably, because the underwire or centre panel of a bra is designed to sit flat against the sternum in the gap that symmastia removes. Sports bras in particular may fail to provide support, because the breasts no longer sit in two separate cups. Swimwear and fitted clothing can highlight the problem, and for many women the emotional impact is considerable.

Uniboob From a Sports Bra: Is It Symmastia?

Most people who search for “uniboob” are not describing symmastia at all. The word is also used for the single, flattened shape a compression sports bra gives the chest, where both breasts are pressed against the body and look like one mound. This is completely normal and harmless. It comes from the bra, not the breasts.

The difference is easy to check. With a sports bra uniboob, the skin between your breasts is still firmly attached to your breastbone, and the normal gap reappears the moment you take the bra off. With symmastia, the skin in the middle has lifted away from the breastbone, so the breasts or implants still meet across the middle when you are not wearing a bra, and often when you lie down too. If your uniboob only happens in a sports bra, you do not have symmastia.

How to Avoid a Uniboob in a Sports Bra

Sports bras come in two main designs. Compression bras hold both breasts flat against the chest in a single panel, which is what creates the uniboob look. Encapsulation sports bras have separate moulded cups, like an everyday bra, that support each breast on its own and keep a visible gap between them, and combination designs use both. In a laboratory study of women running on a treadmill, the breasts moved in step with the body for more of each stride in an encapsulation bra than in a compression bra (Scientific Reports, 2024). If you want good support without the uniboob shape, an encapsulation or combination sports bra with a firm, well-fitted band is the simplest fix.

Is My Cleavage Gap Normal, or Is It Symmastia?

This is one of the most common questions women ask, and it’s an important distinction — because a naturally close cleavage is not the same thing as symmastia. Many women simply have breasts that sit closer together, with a narrow but real gap at the sternum. This is a normal anatomical variation and is not a problem that needs correcting — just as side-set breasts, at the other end of the range, are a normal variation with a wider gap. The key difference is that in a normal close cleavage, the skin and tissue still attach firmly to the breastbone in the midline — there is still a defined, if narrow, separation, and the tissue does not lift away from the chest wall.

In true symmastia, by contrast, the tissue has lost its attachment to the sternum. Instead of a defined gap, there is a soft, mobile bridge of tissue that crosses the midline and lifts away from the chest wall. A useful way to think about it: if you can pinch and lift the skin between the breasts away from the breastbone, or if the implants visibly move together toward the middle when you lie down, that suggests the midline attachment has been compromised — which points toward symmastia rather than simply a close cleavage. Only a proper examination by an experienced surgeon can confirm this, but understanding the distinction helps explain why not every “close cleavage” needs surgery, and why a careful assessment matters.

Types of Symmastia: Congenital, Acquired and Iatrogenic

Understanding which type of symmastia is present matters, because the cause directly shapes how it is corrected.

Congenital symmastia is present from birth. Here, the breast tissue itself has developed across the sternum, so the midline was never fully defined in the first place. It is genuinely rare, and it is covered in more detail below.

Acquired symmastia develops after breast surgery — most commonly breast augmentation — when implants migrate toward the midline over time, or when the tissues that should have kept them apart give way. This is the most common form seen in practice.

Iatrogenic symmastia is a specific sub-type of acquired symmastia caused directly by surgical technique, where the implant pocket was over-dissected toward the sternum during the original augmentation. The pocket was opened too far medially, so the implants were effectively given a channel to drift into the centre. Iatrogenic cases are, in a sense, the most preventable — they trace back to how the original surgery was planned and performed.

Congenital Symmastia: Symmastia Without Implants

Congenital symmastia is present from birth, although it often only becomes noticeable as the breasts develop in the teenage years. Instead of the skin being attached to the breastbone in the middle, a web of skin and soft tissue runs across the sternum and joins the two breasts, so there is no defined cleavage even without implants. It is rare, and relatively few cases have been published in the medical literature (JPRAS, 2012).

The problem is extra tissue over the breastbone rather than implants that have moved, so treatment is different from implant-related symmastia. The usual approach is to remove the excess fat and tissue over the sternum, with liposuction or as part of a breast reduction, then re-attach the skin to the breastbone to recreate the cleavage, with firm compression over the area while it heals (PRS Global Open, 2016). Congenital symmastia can also become more obvious after a breast augmentation: in one series of 100 women treated surgically for symmastia, 59 had the congenital form, and all but three had implants (Plastic and Reconstructive Surgery, 2024). A careful assessment before any augmentation should pick up a pre-existing web across the breastbone.

What Causes Symmastia After Breast Augmentation?

Most modern cases of symmastia are linked to breast augmentation. While augmentation is highly effective for enhancing breast size and shape, it requires careful planning and precise surgical execution, and several factors can increase the likelihood of symmastia developing afterwards.

Implants That Are Too Large

Using implants that are too large for a patient’s natural chest dimensions is one of the most common causes. When the implant width exceeds the width of the chest, the implant has nowhere to sit except by pushing outward against the surrounding tissue. That constant pressure can stretch tissue and force the pocket closer to the sternum over time, with the implants gradually migrating together toward the centre of the chest. This is why an honest surgeon will sometimes advise against a size a patient requests if it exceeds what their frame can safely support; our guide to breast implant sizes explains how size is matched to the chest.

Over-Dissection of the Implant Pocket

The surgical pocket must be created precisely to fit the implant. If dissection extends too far toward the midline, the natural barrier between the breasts is compromised. Even a few millimetres of excess dissection can destabilise the tissue and give the implants room to drift toward one another. This is the mechanism behind iatrogenic symmastia, and it underlines how much the outcome depends on surgical precision during the original operation.

Pre-existing Tissue Weakness

Some patients have naturally thin breast tissue, a narrow sternum, or weak connective tissue, giving them less structural support to hold implants in position. In these cases, symmastia can develop even when the surgery itself was carried out correctly, simply because the tissues do not have the strength to maintain the midline against the weight and pressure of the implants.

Capsule Formation and Healing

All implants form a capsule of scar tissue around them, which is a normal part of healing. However, if this capsule becomes stretched, asymmetrical, or too weak to hold the implant securely, the implant may begin to move medially, producing symmastia. The way an individual heals, which is partly outside anyone’s control, therefore plays a role too.

Symmastia Symptoms: How to Tell If You Have It

The earliest signs of symmastia are often subtle. Patients may notice their cleavage looks less defined than it did, or that bras no longer fit the way they used to, with the centre panel no longer sitting flat against the chest. Over time the signs become more obvious.

A key indicator is the disappearance of the natural gap between the breasts, replaced by a soft tissue bridge across the midline. In more severe cases, the breasts appear as one continuous mound from side to side, with no central definition at all. Many patients notice that the implants move together when they lie down or roll onto their side, and this mobility can make the chest feel unstable or unnatural. While symmastia itself is not usually painful, bras may dig into the wrong places, and exercise can feel awkward. For most women, though, the psychological impact is stronger than any physical discomfort. Symmastia is one form of implant malposition; our guide on how to tell if a breast implant has moved covers the others.

The Emotional Impact of Symmastia

For many women, breast augmentation is a positive, empowering decision, so when a complication like symmastia occurs, the disappointment can be profound. Instead of feeling more confident, patients often feel unhappy with their results, reluctant to wear low-cut tops, and anxious about how their breasts look in swimwear or lingerie. The condition can affect intimacy and self-image, and many women describe avoiding situations where their chest would be on show. There is often a real sense of regret, which can be especially hard when the original surgery was something they had looked forward to. It’s worth saying clearly: these feelings are valid and common, and corrective surgery does more than restore anatomy — for most patients, it restores confidence and the sense of comfort in their own body that the complication took away.

How Symmastia Is Diagnosed

When a patient presents with suspected symmastia, a consultation with an experienced revision surgeon is essential. The examination focuses on the chest anatomy, the type and size of the implants, and the position of the implant pocket. The surgeon assesses how far the implants have migrated across the sternum, whether the tissue in the midline remains attached to the chest wall, and whether the implants are appropriately sized for the patient’s frame. Establishing whether the case is congenital or acquired is important, since it changes the surgical plan. In more complex cases, imaging such as ultrasound or MRI may be used to confirm the implant position and assess the quality of the surrounding capsule before planning the repair.

Symmastia Correction Surgery: How Symmastia Is Repaired

There are no non-surgical treatments that reverse true symmastia. Supportive bras or compression garments may improve the appearance slightly, but they cannot restore the midline or repair the implant pocket, so surgery is the only effective long-term solution. Symmastia correction is a form of revision surgery designed to re-establish the separation between the breasts, recreate a natural cleavage, and secure the implants in the correct position. It is one of the more technically demanding breast revision procedures, and the specific combination of techniques used depends on the individual case. The main techniques include the following.

Pocket repair with internal sutures. The over-dissected pocket along the sternum is closed using internal sutures, recreating a firm boundary in the midline and re-establishing the barrier between the two implant pockets. This is often the foundation of the repair.

Internal bra reinforcement. Specialised surgical internal bra techniques use mesh or biologic materials to reinforce the repaired tissue, providing extra support to hold the correction securely over the long term. This is particularly valuable where the patient’s own tissue is thin or weak and unlikely to hold the repair on its own.

Implant exchange. Oversized implants are a leading cause of symmastia, so they are frequently replaced with smaller implants better matched to the patient’s chest width. Reducing the pressure on the repair dramatically improves the chance of a lasting result.

Pocket repositioning. If the implants were originally placed above the muscle, they may be moved to a new plane below the muscle, which adds stability and gives the repaired midline extra protection and coverage.

The published evidence supports correction but is honest about its limits. A systematic review of 23 studies covering 118 patients grouped the techniques into four families: re-attaching the skin to the breastbone, tightening the implant capsule (capsulorrhaphy), creating a new implant pocket, and muscle repair. Correction was satisfactory in 108 of the 118 patients, and recurrence was the most common complication, reported in 8.5% (JPRAS, 2021).

The procedure is carried out under TIVA (Total Intravenous Anaesthesia) and typically takes several hours, reflecting its complexity. Recovery depends on how extensive the repair is and whether implants are exchanged or repositioned at the same time.

Recovery After Symmastia Correction

After symmastia repair, patients wear a supportive surgical bra to maintain the implant position and protect the new repair while it heals. Some swelling and bruising is expected but resolves gradually over several weeks. During the first two weeks, most patients limit themselves to light tasks and avoid raising their arms above shoulder height, since this protects the internal sutures holding the midline together. Gentle movement is encouraged to support circulation, but exercise and heavy lifting should be avoided for at least six weeks.

Follow-up appointments are scheduled so the surgeon can monitor healing, and in some cases additional imaging may be used to confirm the implants remain stable in their corrected position. Most women return to desk-based work within about two weeks, though full healing and the final settled result take several months to emerge as the tissues consolidate and any residual swelling subsides. Following aftercare instructions closely during this period is one of the most important factors in a durable outcome.

How to Choose a Symmastia Revision Surgeon

Symmastia correction is not a routine operation, and the choice of surgeon has a bigger influence on the outcome than in almost any other breast procedure. It is a revision operating on tissue that has already been altered and, often, weakened, so it demands specific expertise. If you are considering correction, it’s worth looking for a surgeon who operates on the GMC Specialist Register in plastic surgery, who performs breast revision and complication work regularly rather than occasionally, and who can talk you through their specific approach to re-establishing the midline. A good surgeon will also be honest about realistic expectations and the possibility that very weak tissue may need reinforcement or, occasionally, a staged approach.

Be cautious of any clinic that treats symmastia as a simple fix or promises a guaranteed one-operation result, since tissue quality varies and some cases are genuinely challenging. A trustworthy surgeon will give you an honest, individualised assessment at consultation rather than a one-size-fits-all answer. At Centre for Surgery, symmastia correction is carried out by plastic surgeons who specialise in complex revision procedures, with a focus on natural, long-lasting outcomes.

Can Symmastia Be Prevented?

For women considering a first breast augmentation, prevention comes down largely to surgical planning and choosing the right surgeon. Selecting implants that match the chest width is critical, and oversized implants that exceed the patient’s frame dramatically increase the risk. The surgeon must respect the natural midline and avoid over-dissecting the pocket toward the sternum. Patients contribute too, by following postoperative advice carefully — wearing the surgical bra as instructed, avoiding heavy exercise during early healing, and attending follow-up appointments — all of which support optimal healing and reduce the chance of complications developing.

Long-Term Results of Symmastia Repair

The outcomes of symmastia correction are generally very good when the surgery is performed by a skilled revision surgeon. Most patients regain a natural cleavage, an improved breast shape, and renewed confidence. Using reinforcement materials, exchanging to smaller implants, and repositioning below the muscle all help reduce the risk of recurrence. That said, results do vary with individual tissue quality and the severity of the original condition, and a small number of patients with particularly weak tissue may need a further revision if the repair does not hold.

Recurrence is the honest weakness of symmastia surgery, and the literature is candid about it. A 2025 case series describing a new repair technique notes that the established approaches — capsulorrhaphy, dermo-sternal adhesion, neo-pocket creation and muscle repair — are all susceptible to recurrence, which is why so many variations continue to be described (Journal of Surgical Case Reports, 2025). This is the central reason your choice of revision surgeon matters more here than in primary augmentation.

Reinforcement is where the improvement has come from. A technique using the implant capsule itself as a flap to hold the corrected midline reported successful correction across its series, with no recurrence of symmastia and no recurrence of a lowered breast fold (Aesthetic Plastic Surgery). The principle behind it — that the repair needs a structural support rather than sutures alone — is the same one behind the internal bra techniques described above. For the great majority of women, the improvement is lasting and stable — and, just as importantly, the emotional relief of having the problem resolved is significant.

Frequently Asked Questions About Symmastia

Symmastia Correction at Centre for Surgery

Centre for Surgery is a private hospital on Baker Street in London, specialising in complex breast revision procedures including symmastia correction. Our GMC-registered plastic surgeons combine surgical precision with a focus on natural, long-lasting outcomes, operating from our CQC-regulated hospital rated “Good” overall by the Care Quality Commission (CQC). Every patient has a thorough, honest consultation with the consultant who will perform their surgery, to confirm the diagnosis and plan the most appropriate repair, with a recommended two-week cooling-off period and your surgeon’s direct number for the first 24 hours after surgery. If symmastia is affecting your confidence, we’d be glad to discuss how it can be corrected.

Phone: 020 7993 4849 | Email: contact@centreforsurgery.com | Address: 95-97 Baker Street, London W1U 6RN

References

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