Introduction

Augmentation mammoplasty is one of the most commonly requested aesthetic plastic procedures and there is a high satisfaction rate. Complications leading to revision surgery are few and can be divided into early or late. Early complications requiring surgery are infection and haematoma with an incidence of 0.52% [1] and 0.6% [2], respectively. Late complications leading to secondary reversionary surgeries are usually due to implant malplacement and capsular contracture with a reported incidence of 12% [3] and 8% [4], respectively. Revision surgery following augmentation mammoplasty in asymmetrical breasts is common; however, its true prevalence or incidence rate is not known. Revision surgeries following augmentation mammoplasty in asymmetrically breasts may either arise due to lack of identification of a pre-existing condition or due to an inadequate surgical plan or approach. These preventable surgeries are usually requested in between early and late complications periods and are intermediate in nature.

The patient satisfaction rate following augmentation mammoplasty is generally very high; on the other hand, asymmetries of breasts are extremely common with a reported incidence of 87% [5]. Lack of identification or an inadequate approach may potentially lead to dissatisfaction and unnecessary revisions in this group. The commonest asymmetry of breast is the volume discrepancy, and most of these differences can be rectified using different size implants. However, some of these asymmetries may require additional procedures for acceptable results. Quite often, breast augmentation along with an added procedures leads to an improvement but with a failure of intent. In a minority of these patients, residual deformity may persist regardless of the added simultaneous procedures or measures taken. These severe deformities or asymmetries may be confined to the breasts or may coexist with other underlying asymmetries. Some of these asymmetries may be extremely difficult to correct, and a perfect result is unlikely to be achieved. It is important that these patients should be identified preoperatively and clearly informed about the expected outcome of the procedure. A comprehensive classification, understanding and documentation of these deformities are essential so that an expected result is a part of the informed consent. If these differences are not discussed or included in the preoperative plan, the inadequate results may give rise to issues postoperatively. A compromised result is likely to leave a patient extremely unhappy with a medico-legal potential.

Asymmetries of breasts commonly involve breast volume, breast shape, nipple level difference in vertical axis [5, 6] or its placement in horizontal axis [7]. The disparities may also exist in nipple to inframammary crease distance, nipple areolar complex size or inframammary crease level. Associated ribs, costochondral junctions or sternal deformities can indirectly contribute breast asymmetries and can influence the outcome of augmentation mammoplasty. These asymmetries are common and a collective incidence of up to 87.8% has been reported [5]. A prospective evaluation of the patients was done to record these asymmetries and deformities. The goal and objective was to identify the common breast volume, shape, skin envelope and nipple positioning asymmetries. Chest wall, costal and sternal discrepancies were also recorded. Underlying muscle asymmetries or deficiencies were difficult to assess preoperatively but an intra-operative finding were recorded and correlated to the preoperative findings.

Material and methods

From January to December 2007, 312 augmentation mammoplasties were performed. The mean age of the patients was 30.4 ± 9.1 years (range 18–58). The mean size of the implant was 325 ± 53 cm3 (range 200–620). Different size implants were used in 9% patients with a mean difference of 56.3 ± 33.7 cm3 (range 20–180). Patients were assessed for asymmetry of breast, chest, distance between jugular notch to nipple areolar complex and nipple areolar complex to inframammary crease. Overall prevalence of tuberous breast was also recorded. Muscle splitting biplane technique was used by the author for all procedures.

Results

Breast volume asymmetries

Breasts were symmetrical in 53.5% (n = 167). Left breast was larger in 29.8% (n = 93) as compared to 16.7% (n = 52) on the right, and the difference was significant (P value < 0.001).

Chest wall asymmetries

The chest wall was bilaterally symmetrical in 89.7% (n = 280) and thoracic deformities or asymmetries were seen in 8.6% (n = 27). The chest was prominent in 6.7% (n = 21) on the left side as compared to 1.9% (n = 6) on the right, and the difference was significant (P value < 0.003) Pectus excavatum and carinatum was seen in 0.6% (n = 2) and 1% (n = 3), respectively.

Jugular notch to nipple areolar complex distance differences

The jugular notch to nipple areolar complex (NAC) distance was same on two sides in 67.2% with a mean distance of 19.7 cm (n = 207).

In group (21.4%) with the left breast NAC lower (n = 66) than the right, the mean left NAC was 20.7 cm when compared to 19.04 cm on right.

In the group (11.2%) with right NAC lower than the left (n = 35), the mean NAC on the right was 21.2 cm as compared to 20.4 cm on the left.

The left breast NAC (n = 66) was measured twice as commonly lower than the right (n = 35) and the difference between the two groups was significant (p value < 0.001).

Nipple to inframammary crease distance differences

Nipple to inframammary crease (IMC) distance was similar in 77.1% of patients (n = 235) with a mean of 6.69 cm.

Measurement had a higher value on the left in 13.1% (n = 40). In this group of patients(n = 40), the left mean nipple to IMC crease distance was 6.9 cm as compared to 6.17 cm on the right.

The group (n = 30) with a larger measured nipple to IMC distance on the right (9.8%), the mean distance on the right was 7.12 cm as compared to 6.52 cm on the left. Though the incidence of the measured nipple to IMC distance was more common on the left (n = 40) than the right (30), the difference between the two groups was without any statistical difference (p value = 0.2; Tables 3 and 4).

Tuberous breasts were seen in 3.9% (n = 12).

Statistical analysis

The left and right side of the breast were compared regarding their size, suprasternal notch to nipple areolar complex and nipple areolar complex to inframammary crease measurement differences and chest wall asymmetry using the Student’s t test. A p value of <0.05 was considered statistically significant for all the tests.

Discussion

A detailed account of breast asymmetries and their treatment is beyond the scope of this article. A short summary of common breast asymmetries observed in patients requesting augmentation mammoplasty along with its classification is presented. These asymmetries may be primary in origin or secondary due to thoracic wall deformities. Thoracic wall deformities may arise from the sternum, the costochondral junction, the ribs or overlying muscles. Asymmetries may also arise primarily from breast size and shape or the nipple areolar complex and the inframammary crease level, size or position discrepancies. A system of classification is helpful to document these asymmetries and to include them in the informed consent (Tables 1 and 2).

Table 1 Breast asymmetries based on bony chest wall deformities
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Table 2 Breast asymmetries based on soft tissue discrepancies
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Most of these commonly seen asymmetries were evaluated in a prospective study performed by the author. Breast size difference was present in 46.5% of the patients. Of these, the left breast was larger (29.8%) twice as many times as the right (16.7%), and the difference was significant (P value < 0.001). Vertical nipple areolar level was different in one third of the patients and the left nipple areolar complex was twice as commonly (21.4%) lower than right (11.2%), and the difference was significant (p = <0.001). Similar observation were seen when nipple to inframammary crease measurements were recorded. The left side distance measured more and was twice as common in incidence as on the right without being statistically significant. Different degrees of chest asymmetries was present, and again, they were significantly more prominent on the left side (p ≤ 0.003). However, only the minority of these patients needed a different size implant and even fewer needed unilateral mastopexy for nipple level correction in the vertical axis. When the nipple areolar complex placement is asymmetrical in the horizontal axis, it is more lateralised than medialised in nature and lateralisation is more common on the right breast. In the more common unilaterally lateralised nipples, authors lateralise the pocket on the affected side to offset its appearance [7].

Chest asymmetries originating from the sternum are quite common and include pectus excavatum, pectus carinatum or “S” shape sternum (Fig. 1a–f). Other deformities may arise from the costochondral junction (Fig. 2a–b), ribs (Fig. 3a–b) or can involve one half of the chest wall, hemithoracic disjunction, which can present either in the anteroposterior or the horizontal plane (Fig. 4a–d) [6, 8]. Thoracic wall or chest deformities can present independently with an indirect effect on the breast or quite often may be associated with breast asymmetries at the same time. A noticeable pectus-carinatum may interfere with an adequate cleavage and pectus-excavatum will result in a deeper cleavage. “S” shaped sternum is quite common, and good results can be achieved with the use of an adequate size implant in a suitable pocket. Sternal deformities can often affect the origin of pectoralis and may interfere with adequate muscle cover if a submuscular pocket is chosen (Fig. 1a–f). Costochondral joint prominence involving the entire column or upper joints can be difficult to conceal because the flat surface on the back of the implant tends to sit or slide lateral to the prominence. The resulting lateralisation of the implant may give rise to wider cleavage with visible prominence of the costochondral joints (Fig. 2a–b). Rib asymmetries involving the chest wall are not uncommon. Lower ribs or the costal margin may not have much influence on the outcome of the results, but depressed or elevated ribs involving the upper thoracic cage may need careful planning for implant selection. Small differences can be left alone, but noticeable difference may require an adjusted size and profile (Fig. 3a–b). When similar size or profile implants are used in these cases, the implant may appear as upper pole fullness on the prominent ribs side in the immediate postoperative period and may lead to a false impression of haematoma. The diagnosis can be difficult to rule out clinically if there is no record of the underlying asymmetry especially if drains are not used. These uncorrected asymmetries may continue to persist postoperatively. Hemithoracic disjunctions are a condition in which two sides of the chest wall do not match, either in anteroposterior or horizontal axis. Hemithoracic disjunction in the anteroposterior plane requires meticulous planning and selection of implants (Fig. 4a–b). The prominent side requires low profile and small volume implants and the depressed side will need a larger volume and extra high profile implant. Use of adjustable implants in these cases can be useful for more accurate correction. Hemithoracic disjunction in the horizontal plane, with or without breast asymmetry or anteroposterior discrepancy, are easier to manage, but a meticulous measurement of the base of the breast is required to select a suitably size implant (Fig. 4c–d). The patient needs to be warned that implant selection is to improve the appearance of the breast and not to correct the underlying bony dimensional asymmetry. The soft tissue abnormalities of the underlying muscle can also have an indirect effect on breast shape and appearance. The findings were noticed incidentally during the operation and they were documented in the operative notes. The findings were later correlated with the preoperative photos. The breasts with underlying lower pectoral hypoplasia presents as lack of fullness in the lower pole. Major lower pectoral hypoplasia may give an appearance of constricted breasts. Use of round cohesive gel silicone implants in these cases almost always gives a natural lower pole fullness with adequate nipple areolar complex projection (Fig. 5a–f). Anomalous rectus sternalis may present unilaterally or bilaterally and a unilateral rectus sternalis may give rise to an asymmetrical cleavage in a hypoplastic breast [9].

Fig. 1
figure 1

a Preoperative lateral view showing pectus carinatum deformity. b Postoperative results after using 300 cm3 round cohesive gel silicone implants in muscle splitting biplane. c Preoperative photo of a patient presenting with a noticeable pectus excavatum deformity, d postoperative results 1 year after augmentation mammoplasty in muscle splitting biplane with 400 cm3 round, textured cohesive gel silicone implants. e Preoperative oblique views showing “S” shaped deformity of the sternum and, f Six months after using 300 cm3 implants in muscle splitting biplane

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Fig. 2
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a A young 23-year-old patient presenting with breast atrophy following breast feeding. Right parasternal prominence is obvious due to entire row of prominent costochondral joints. b Six months following mammoplasty after using 400 cm3 cohesive gel silicone implants. Upper parasternal prominence persisted after mammoplasty

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Fig. 3
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a Patient presenting with severe left unilateral prominent ribs with associated breast asymmetry. b Postoperative views following 440 cm3 high profile and 300 medium profile cohesive gel silicone implants on the right and left side, respectively

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Fig. 4
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a, b Anteroposterior hemithoracic disjunction. a A side view of a 20-year-old patient with anteroposterior Hemithoracic disjunction. Her right hemithorax dimension is markedly smaller than its left counterpart. b Postoperative results after a 200-cm3 cohesive gel silicone low profile implant on her left side and 330 cm3 high profile on her right side. Breast symmetry has been restored without any changes to thoracic mismatch. c, d Horizontal hemithoracic disjunction. a A front view of a 19-year-old patient with horizontal Hemithoracic disjunction. Her right hemithorax has a narrower dimension than its counterpart on the left side. b Postoperative results after a 325-cm3 extra high profile cohesive gel silicone implant on her right side and 295 cm3 moderate profile on her left side has restored the breast symmetry. Thoracic mismatch in horizontal disjunction has been overshadowed after improvement in breast symmetry

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Fig. 5
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a, b Minor lower pectoral hypoplasia. a Preoperative view of a patient with bilateral minor lower pectoral hypoplasia showing no clinical deficit. b Postoperative views after 350 cm3 round high profile cohesive gel silicone implants. Hypoplastic muscle was an intra-operative finding. c, d Moderate pectoral hypoplasia. c Preoperative views of a patient with bilateral moderate lower pectoral hypoplasia presenting with lack of lower pole fullness or skin constriction. d Postoperative views after augmentation mammoplasty using 350 cm3 round high profile cohesive silicone gel implants. Intraoperative finding showed very thin pectoralis below nipple level. e, f Major pectoral hypoplasia. e Preoperative views of a 19-year-old girl with severe bilateral lower pectoral hypoplasia. f Six months postoperative results after augmentation mammoplasty using 325 cm3 high profile cohesive gel silicone implants. Patient had nonexistent pectrolis major in its lower half

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Asymmetries arising from the breast soft tissue are more common than asymmetries of the chest wall. They can be broadly divided into asymmetries arising from shape or asymmetries due to volume differences. Shape differences may be due to inframammary crease level asymmetries, medial flaring or its lateral counterpart. Inframammary crease differences are easily correctable provided there is no nipple level asymmetry (Fig. 6a–b). Medial flaring is commoner (Fig. 7a–b) than its lateral counterpart (Fig. 7c–d) and restoration of a round lower pole can be achieved by undermining but corrected medial flaring often leave a crease running on the breast fold (Fig. 7a–b). Asymmetries associated with tuberous breasts are quite complex and can be challenging to correct, these deformities need to be individually assessed and appropriately treated (Fig. 8a–b). Volumetric differences of the breasts are more common than thoracic asymmetries or asymmetries arising from breast shape differences. These volumetric differences can be corrected by using different volume, dimension and profile implants. However, the exact amount of volume difference required to correct these asymmetries can be difficult to judge preoperatively or intra-operatively and different asymmetries sometime respond differently to the adjusted volume difference (Figs. 6, 9, 10, and 11). Absolute symmetry can often be difficult to achieve by using different size implants and over or under correction remains a possibility. Adjustable implants or intra-operative use of implant sizers remain an option. Key to satisfactory outcome after augmentation mammoplasty in an asymmetrical breast is the position of the nipple areolar complex. Asymmetry of volume, shape or inframammary crease can be satisfactorily corrected if the vertical axis of the nipple areolar complex axis is symmetrically placed (Figs. 6, 9, 10, and 11). Nipple areolar complex asymmetries in vertical axis are difficult to correct with volume adjustment alone (Fig. 11a, b). These asymmetries often require simultaneous unilateral periareolar or vertical scar mastopexy along with implant volume adjustment for an adequate result if the nipple level difference is noticeable (Fig. 12a, b). Asymmetries associated with a unilaterally lateralised nipple areolar complex malplacement in the horizontal axis may require lateralisation of the pocket on the lateralised nipple side. This procedure helps to offset the lateralised appearance of nipple areolar complex [7].

Fig. 6
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a A preoperative photograph of a 27-year-old girl after two children. Her left breast is larger, inframammary crease positioned little lower than the right. Nipple areolar complex are symmetrically positioned. b Eight months postoperative results after augmentation mammoplasty in muscle splitting biplane, using 300 and 260 cm3 textured, round, high profile cohesive gel silicone implants, on the right and left side, respectively

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Fig. 7
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a, b Medial Flaring. a A 23-year-old girl with bilateral flaring of breasts. b Six months postoperative views after augmentation mammoplasty with 400 cm3 round high profile cohesive gel silicone implants. Undermining of the skin under medial fold of the breast has resulted in producing a round fold but a crease representing the original inframammary fold persisted postoperatively. c, d Lower lateral breast fold constriction. c A 35-year-old patient presenting with lateral fold constriction. d Six months postoperative views after augmentation mammoplasty using 400 cm3 round high profile cohesive gel silicone implants. No residual crease is seen when undermining is performed in these cases as opposed to it medial counterparts

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Fig. 8
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a A 20-year-old patient with severe tuberous breast deformity. Right breast has more noticeable infra areolar skin constriction than right. Upper pole fullness is almost symmetrical. b One year after augmentation mammoplasty in muscle splitting biplane, using 260 cm3 high profile cohesive gel silicone implant through inframammary crease

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Fig. 9
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a A 21-year-old girl with mammary hypoplasia along with minor asymmetry of breasts. Left breast is slightly larger than the right. There is no asymmetry of nipple areolar complex or any inframammary crease discrepancy. b Results after augmentation mammoplasty in muscle splitting biplane using 275 and 255 cm3 round, high profile cohesive gel textured implants, on the right and left side, respectively

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Fig. 10
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a A 42-year-old patient with asymmetry of breasts and inframammary crease. Left breast is larger along with lower inframammary crease when compared to the right. Both nipple areolar complexes are symmetrically placed in vertical level. b Postoperative results after using 400 and 350 cm3 high profile, textured silicone cohesive gel implants, on the right and left side, respectively

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Fig. 11
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a A young mother interested in augmentation mammoplasty after having pregnancy related changes to her breasts. She has a noticeably larger right breast with nipple areolar complex positioned asymmetrically. b Postoperative results after 6 months when 260 and 300 cm3 round, textured, cohesive silicone gel implants were placed, on the right and left sides, respectively. A small breast volume difference is present along with residual asymmetry of nipple areolar complex level. Nipple areolar complex asymmetry tends to be obvious if the preoperative difference is ≥1 cm

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Fig. 12
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a Major breast asymmetry with noticeably larger breast on the right associated with grade C ptosis. b Results after bilateral breast augmentation in muscle splitting biplane with right vertical scar mastopexy; 220 cm3 low profile and 365 cm3 high profile textured cohesive gel silicone implants were used on the right and left side, respectively

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Breast morphometry has been done in volunteers with no intention of having an augmentation mammoplasty [10], in patients requesting reduction mammoplasty [11] and values from aesthetically perfect breasts models have been used for breast reconstruction [12]. Asymmetries of breast are common and have been a part of discussions [13] and often reported on the basis of their embryological and developmental origin [14] or their morphology [15]. Treatment of these developmental asymmetries has been described with [16] or without the use of implants [14]. However, a comprehensive morphological classification of these asymmetries is lacking along with their relative distribution in patients requesting augmentation mammoplasty. One study has reported an overall incidence of 88% of breast asymmetries without mention of their relative distribution on each side [5]. Brown et al., in another study, measured three groups of patients, one requesting breast reduction, second requesting breast augmentation and the third group comprised of normal volunteers. Asymmetries were noted on two sides, but the study did not mention which one of the three groups was used for statistical analysis [11]. Smith et al., in their breast volume and anthropomorphic measurement study, compared the breast volume, axillary to nipple distance and nipple to the inframammary fold crease in 55 volunteers with no statistical difference. No suprasternal notch to nipple areolar distance or chest wall asymmetries were included in the study [10]. The incidence of asymmetrically placed nipple areolar complex in the horizontal plane has been described, and the article also took into account their relative distribution on two sides. These asymmetrical nipples can be either medially or laterally placed and were seen in 12% of 312 patients who had their breast augmentation performed in a year. Of these, 9% were on the right side and were laterally placed [7].

The current study involves measurements of the suprasternal notch to nipple areolar complex and nipple to inframammary crease distance. Observations and recordings were also made of any breast volume and chest wall asymmetries in 312 patients who had their augmentation mammoplasty in 2007 (Tables 3 and 4). All measured and observed parameters, which included nipple to sternal notch, nipple to inframammary cease distance, breast volume and thoracic cage asymmetries, showed a higher incidence of hyperplasia on the left side. The differences were significant in all but one parameter when data were statistically analysed (Tables 3 and 4). The breast volume and chest wall asymmetries were present in up to 46% and 8.6% of the patients, respectively. Of these, only 9% needed different sized implants. Nipple areolar complex vertical level asymmetries were present in almost 33% of the patients and only a minority needed mastopexies. The mean difference of the measured suprasternal to nipple areolar complex was less than 1 cm and hence obviated the need of mastopexies in majority of these 33% of patients (Table 4). Quite often, patients requesting breast augmentation are not aware of these asymmetries especially if the differences are small. Most of these patients rarely spend any time looking or observing these asymmetries before their operation but are likely to spend more time after surgery and often notice these differences. Unrecorded and uncorrected asymmetries that were not picked up prior to the surgery can potentially put a surgeon in a defenceless and difficult position.

Table 3 Incidence of various chest and breast asymmetries along with their relative distribution on two sides
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Table 4 Relative distribution of mean distances between asymmetries of supra sternal notch to nipple areolar complex and nipple to inframammary crease distances
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Conclusion

Breast and chest wall asymmetries are commonly seen in patients requesting for augmentation mammoplasty and their preoperative identification and planning is mandatory for an optimal result. When present, majority of the hyperplasia of breast and chest are on the left side.