Symmastia: causes, signs, diagnosis and treatment

In this article, we explain what symmastia is, including the difference between congenital and acquired cases, why it can occur after breast augmentation, and the signs that may indicate this condition. We also discuss how symmastia is diagnosed, how it can be corrected through revision breast surgery, and what patients can expect during recovery and after treatment.

What is symmastia?

Symmastia is a condition characterised by the loss of the normal separation between the breasts due to an abnormal connection or extension of breast tissue, skin, or implant pockets across the midline of the chest. The condition affects the intermammary space, the anatomical area between the breasts that normally maintains separation and defines the central cleavage. In symmastia, this space becomes reduced or absent, causing the breasts to appear joined at the centre rather than maintaining distinct contours.

Congenital vs. acquired symmastia: Understanding the different types

Symmastia can be classified into two types based on whether it develops naturally or occurs due to changes after breast surgery.

• Congenital symmastia: A rare anatomical condition present from birth, caused by an abnormal extension or connection of breast soft tissue across the midline of the chest. It is related to natural breast development and is not caused by implants or previous surgery.
• Acquired symmastia: A condition that develops later, most commonly after breast augmentation, when the separation between the breasts is altered due to factors such as implant pocket changes, excessive medial dissection, implant size mismatch, or reduced tissue support.

What are the signs of symmastia?

The main aesthetic feature of symmastia is the loss of the natural separation between the breasts, resulting in an abnormal connection across the centre of the chest. Common signs include:

• Reduced or absent intermammary space between the breasts.
• Breasts appearing connected at the midline of the chest.
• Implants positioned too close together in cases related to breast augmentation.
• Fullness or a visible skin bridge over the sternum.
• Altered cleavage shape compared with the patient’s natural breast contour.

The appearance of symmastia breast changes can vary depending on whether the condition is related to natural anatomy or previous breast surgery.

Why does symmastia develop after breast augmentation?

Symmastia after breast augmentation occurs when the tissue boundary separating the two implant pockets is disrupted, allowing the implants to move too close together at the centre of the chest. During breast augmentation, each implant is placed in an individual pocket designed according to the patient’s anatomy. If the medial border of these pockets is weakened or positioned too close to the sternum, the natural separation between the breasts can be reduced or lost.

This may be associated with:

• Excessive dissection of the inner implant pocket.
• Implants that are too wide for the patient’s chest anatomy.
• Insufficient soft tissue support around the implants.
• Previous breast implant surgery affecting pocket stability.

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How is symmastia diagnosed?

Symmastia is diagnosed through a clinical breast examination, where the surgeon evaluates breast anatomy, tissue support, and the position of the breasts or implants. During assessment, the surgeon examines:

• The width of the intermammary space and cleavage appearance.
• Breast tissue distribution and soft tissue support.
• Implant position and pocket stability in patients with breast implants.
• Previous breast surgery and implant history.

Diagnosis is mainly based on physical examination, although imaging may be recommended in selected cases when additional evaluation is needed.

How is symmastia corrected during revision breast surgery?

Symmastia is repaired through revision breast surgery by correcting the abnormal implant pocket and addressing the factors responsible for the loss of breast separation. The approach depends on the cause of symmastia, implant position, and tissue support. Correction may involve:

• Medial capsulorrhaphy: Tightening the inner implant pocket to recreate the space between the breasts and prevent medial displacement.
• Internal pocket repair: Reshaping the implant pocket to restore proper boundaries and improve implant stability.
• Implant repositioning or replacement: Adjusting or changing implants when their size, shape, or position contributes to symmastia.
• Pocket reinforcement: Adding additional support in selected cases where tissue quality is limited or there is a higher risk of recurrence.

The goal is to restore natural breast separation, maintain stable implant positioning, and achieve a balanced breast contour.

Recovery and expected outcomes after symmastia correction

Recovery after symmastia correction typically takes 4–6 weeks for initial healing, while final breast contour and implant position continue to stabilise over 3–6 months.

• First 1–2 weeks: Swelling, bruising, tightness, and discomfort are common. A supportive surgical bra is recommended, and activities that place tension on the breast tissues should be avoided.
• Weeks 3–6: Most patients gradually return to normal activities, while strenuous exercise and heavy lifting remain restricted to protect the surgical repair.
• Months 3–6: Residual swelling decreases, breast tissues soften, and the final position and contour become more defined.

Expected outcomes after symmastia correction include restoration of the natural space between the breasts, improved breast contour, and more stable implant positioning when implants are involved. The final result depends on the severity of the condition, tissue quality, implant characteristics, and the corrective approach used.

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