Breast asymmetry: correction through augmentation

Breast asymmetry is a very common phenomenon in women, more or less noticeable depending on the shape of the chest. When this difference in size, shape or position between the two breasts is visible or hard to live with, it can be corrected with a breast surgery procedure to restore balance and give the bust a harmonious, natural appearance.

What is breast asymmetry and is it common?

We speak of breast asymmetry (or breast dissymmetry) when the two breasts show a perceptible difference in volume, shape, projection or position. A slight difference between the two breasts is in fact the rule rather than the exception: almost all women have breasts that are not perfectly identical, without it being noticeable day to day.

Plastic surgery research confirms this. A study by N. I. Cruz, published in 2018 in Aesthetic Plastic Surgery, found a difference in breast volume in roughly 41 to 47% of women consulting for plastic surgery, and a chest-wall asymmetry in 10 to 12% of them. Taking all forms of asymmetry into account (volume, shape, position, areolae, chest), a review by U. D. Khan (2024) estimates that some degree of asymmetry may be present in up to 87% of patients. In other words, having an asymmetric chest is perfectly common and in no way abnormal.

The question is therefore not so much the presence of asymmetry as its degree. As long as it remains subtle, it warrants no treatment. It is when it becomes visible, awkward when getting dressed or difficult to live with that surgical correction can be considered. As a rough guide, an MRI study by X. Du (2024) showed that patient satisfaction dropped sharply once the volume gap between the two breasts exceeded around 40%.

What causes the difference in size between the two breasts?

Breast asymmetry can stem from a range of factors, including in particular:

• a genetic predisposition (a congenital anomaly) causing one breast to develop more than the other, for example in cases of Poland syndrome or tuberous breasts (elongated, sometimes described as triangular in shape);
• hormonal factors: puberty, menopause or other hormonal fluctuations can influence the size and appearance of the breasts;
• events in a woman’s life such as pregnancy or breastfeeding, which can accentuate this asymmetry. This is then referred to as post-pregnancy asymmetry;
• an impact, trauma or the presence of a cyst or abscess temporarily deforming a breast;
• breast cancer requiring a mastectomy (post-traumatic asymmetry).

It is also worth noting that asymmetry is statistically more frequent in larger breasts and in women who have not had children (R. Kayar, 2015).

The different forms of breast asymmetry

Breast dissymmetry can take several forms, including in particular:

• a difference at the level of the inframammary fold (one breast lower than the other), which accounts for the majority of cases;
• one breast larger than the other (also a frequent case);
• a difference in the position of the areolae and nipples;
• a constriction of the base of one breast causing a difference in shape (a triangular-shaped breast);
• a chest asymmetry, which usually leads to a disparity in volume and shape.

An accurate diagnosis of the specific form directly guides the choice of correction technique.

The surgical techniques to correct asymmetric breasts

Several techniques to correct breast asymmetry can be considered depending on the diagnosis made by the surgeon:

• a breast lift in the event of ptosis of one of the breasts (ptosis correction or mastopexy): it is indicated when the asymmetry results from a difference in position. It then consists of raising the lower breast to the same level as the other;
• a breast reduction, used in the presence of a volume asymmetry. It consists of reducing the volume of the larger breast and, in some cases, raising it (ptosis correction) to achieve a symmetrical bust. When it involves only one breast, it is referred to as a unilateral reduction;
• a breast augmentation (with implants or with lipofilling): this time the aim is to increase the volume of the smaller breast in order to achieve breast symmetry. This augmentation can be carried out by placing a breast implant or through an injection of the patient’s own fat (autologous fat transfer);
• combining the two techniques, augmenting the smaller breast while reducing the larger one, is also possible to rebalance a marked asymmetry.

In most cases, the solution to breast asymmetry therefore involves augmenting the smaller breast, since a difference in volume is the most frequent cause of dissymmetry.

A closer look at correcting breast asymmetry through breast augmentation

Correcting non-symmetrical breasts is most often carried out through a breast augmentation procedure, as a difference in volume is one of the main causes of this dissymmetry.

How the procedure unfolds

A consultation is held with the specialist, who examines in particular the characteristics of the breasts (shape, volume, projection) and gathers the patient’s needs and expectations in order to decide together on the most suitable type of procedure. A mammogram and an ultrasound are performed to confirm the patient’s state of health, and an appointment with the anaesthetist is scheduled.

How the procedure then unfolds depends on the technique chosen by the surgeon in agreement with the patient. In every case, anaesthesia is administered (local with sedation, or general for greater comfort). The procedure itself lasts between 1.5 and 2 hours, with the patient usually leaving the hospital the next day or sometimes the same evening (as a day case):

• for a breast asymmetry correction with augmentation using a breast implant, an incision is made in the inframammary fold (inframammary approach), at the top of the armpit (axillary approach) or under the nipple (periareolar approach). A pocket is then created to house the implant chosen beforehand. The surgeon then positions the implant either:
  • in front of the pectoral muscle (premuscular or retroglandular position);
  • behind the pectoral muscle (retromuscular position);
  • or in a Dual Plane position (both in front of and behind the pectoral muscle).

Once the implant is positioned, the incisions are carefully closed with self-absorbable sutures to minimise the visibility of the scars.

• for a breast asymmetry correction with augmentation using breast lipofilling, the surgeon performs a liposuction of an amount of excess fat from one or more areas of the patient’s body (belly, hips, arms, etc.). The harvested fat is then treated and centrifuged, then reinjected into the less developed breast to rebalance the proportions;
• breast augmentation can also be composite, that is, combining the placement of an implant with a fat injection over the top, in order to achieve an even more natural result.

Results and recovery

The recovery following a breast asymmetry correction through augmentation is generally moderate. It is most often limited to swelling and tissue tension in the operated breast, while the skin adjusts to the new volume. Any relatively mild pain can be relieved with painkillers.

You should, however, wear a compression bra for around 6 weeks to consolidate the result, and take great care to disinfect the incisions to prevent any infection. Physical exertion should also be limited for several weeks.

The results of a breast asymmetry correction are visible immediately after the procedure, but generally take 3 to 6 months to become final, as the swelling subsides. The bust then appears more even and symmetrical, with redefined curves and matching proportions between the two breasts.

One breast larger than the other after a breast augmentation: normal or worrying?

It is common for a patient to notice, in the days and weeks following a breast augmentation, that one breast appears higher, larger or firmer than the other. In the vast majority of cases, this asymmetry is temporary and is part of the normal course of recovery.

The two sides do not always settle at the same rate, and the implants do not move into place simultaneously. This is the so-called implant « drop » phenomenon: the implant softens and gradually migrates towards its final position. English-speaking surgeons call this drop and fluff. This process usually begins between the 2nd and 6th week and continues until the bust stabilises, most often after 3 to 6 months. During this period it is therefore normal for symmetry not yet to be perfect.

An asymmetry that persists beyond this timeframe, however, or that is accompanied by pain, marked firmness or deformation, should be assessed by the surgeon. It may be linked to a difference in the positioning of the implants, to a capsular contracture, or to a pre-existing asymmetry that was not entirely corrected. A surgical revision or an adjustment by lipofilling can then help refine the result. The plastic surgery literature shows that these secondary corrections (revision surgery) give good results that are stable over time.

Can breast asymmetry correction through augmentation be covered by French national health insurance?

In certain situations, French national health insurance can cover a breast asymmetry correction through augmentation. This is the case in particular for:

• a congenital malformation;
• a breast asymmetry deemed disabling (such as Poland syndrome or tuberous breasts);
• an asymmetry with no congenital cause, provided it is significant enough (for example in the presence of agenesis or breast hypoplasia).

The level of coverage is, however, very often determined by the degree of asymmetry. A procedure for a minor asymmetry has little chance of being covered. The correction of a major asymmetry, on the other hand, may result in reimbursement once the file has been approved by an Assurance Maladie medical adviser.

In practice, the process most often follows three steps: a surgical consultation during which the surgeon assesses the asymmetry and builds the medical file (photographs, measurements), the submission of a request for prior agreement to French national health insurance, then waiting for the medical adviser’s response. If agreement is granted, the portion not reimbursed (in particular any fee supplements) may be covered by your complementary health insurance. Speak with your surgeon from the very first consultation to build a file to that end.