Keywords breast reconstruction - stacked flaps - deep inferior epigastric perforator microsurgery
The use of two abdominally-based flaps for unilateral breast reconstruction is a valuable
tool that was first described in 1985 by Ishii et al.[1 ] The majority of patients in Ishii's series had large soft-tissue requirements owing
to radical mastectomies or radiation necrosis of the chest wall. The authors reconstructed
defects using both sides of the lower abdominal wall as pedicled flaps based on the
left and right superior epigastric vessels. This technique was refined by Spear who
proposed burying one of the two flaps below the other in situations when the skin
from a single flap would be sufficient to restore the breast skin envelope, but the
volume of a single flap would be insufficient.[2 ]
More recently, some surgeons have used both hemiabdomens as either “stacked” deep
inferior epigastric perforator (DIEP) flaps (two separate DIEP flaps used to reconstruct
one breast) or bipedicle-conjoined DIEP flaps (both hemiabdomens transposed with their
respective inferior epigastric pedicles as a single conjoined unit) for unilateral
breast reconstruction in patients in whom the volume or quantity of skin of a single
flap is inadequate to create a breast mound that approximates that of the unaffected
contralateral breast.[3 ]
[4 ]
[5 ] This technique has been applied primarily to patients with a low body mass index
(BMI) and accordingly, the volume of flaps used in such reconstructions has been relatively
small.[6 ]
[7 ]
[8 ]
[9 ]
[10 ] DellaCroce et al, for instance, published a series of 55 patients who underwent
stacked DIEP flaps for unilateral breast reconstruction over a 3-year period. In their
series, the average weight of the patient was 138 pounds (range: 108–190 pounds),
and the average weight of the two DIEP flaps combined for each reconstruction was
596 g.[11 ]
Despite the preferential use of bipedicle-conjoined flaps for breast reconstruction
in patients with a low-to-normal BMI, the authors believe that many patients on the
other end of the BMI spectrum, those in the overweight and obese categories, can also
benefit from this technique. In contrast to normal weight patients who present a particular
challenge that results from a paucity of donor tissue, many obese and overweight patients
possess a premastectomy breast size and morphology that is difficult to replicate
with standard reconstructive techniques. These patients, especially those in the obese
category (BMI > 30), are considered by many to be poor candidates for autologous reconstruction
because of observed increases in complication rates when compared with nonobese patients.[12 ] As such, many overweight and obese patients are offered only implant-based reconstruction
or no reconstruction at all.[13 ]
[14 ] This series examines the safety and efficacy of bipedicle-conjoined DIEP flaps for
unilateral breast reconstruction in overweight and obese patients.
Methods
The authors conducted a retrospective review of the two senior authors' patients from
2013 until 2018. In this time period, 71 consecutive patients were identified as having
undergone unilateral breast reconstruction with bipedicle-conjoined DIEP flaps. These
patients were divided into two cohorts: normal weight or underweight (BMI < 25, n = 30) and overweight or obese (BMI > 25, n = 41). The two cohorts were then compared based on demographic factors, comorbidities,
and complications.
Demographics and comorbidities evaluated include age at time of reconstruction, medical
comorbidities, and previous abdominal or breast surgery. Medical comorbidities include
BMI, hypertension, diabetes, history of chemotherapy, history of prereconstruction
radiation, and the use of nicotine within one year of surgery ([Table 1 ]). Operative details reviewed include mastectomy weight and flap weights (initial
and final). In addition, the rate of delayed reconstructions and concomitant contralateral
procedures were reviewed ([Table 2 ]).
Table 1
Demographics and comorbidities
Normal
Overweight/obese
p -Value
Number
30
41
NA
Age at reconstruction (y)
52.8 ± 7.9
53.2 ± 8.9
0.42
BMI (kg/m2 )
23.1 ± 1.3
28.9 ± 4.0
<0.01
Medical comorbidities (%)
Smoking (within 1 y)
2 (6.7)
4 (9.8)
0.34
Coronary artery disease
2 (6.7)
2 (4.9)
0.46
Hypertension
5 (16.7)
14 (34.1)
0.06
Diabetes
1 (3.3)
3 (7.3)
0.25
Previous abdominal surgery (%)
15 (50.0)
22 (53.6)
0.44
Previous breast surgery (%)
19 (63.3)
22 (53.6)
0.16
Chemotherapy (%)
14 (46.7)
20 (48.7)
0.44
Radiation therapy (%)
12 (40.0)
20 (48.7)
0.27
Average follow-up (mo)
31.6 ± 15.9
27.2 ± 16.5
0.15
Abbreviations: BMI, body mass index; NA, not available.
Table 2
Operative details
Normal (n = 30)
Overweight/obese (n = 41)
p -Value
Mastectomy weight (g)
472.8 ± 181.8
692.8 ± 261.1
<0.01
Flap weight: initial (g)
559.6 ± 179.6
1,059.3 ± 445.7
<0.01
Flap weight: final (g)
533.5 ± 183.8
813.9 ± 242.7
<0.01
Perforators per flap (n )
1.5 ± 0.5
1.6 ± 0.5
0.30
Second flap anastomosed to retrograde IMA (%)
23 (76.7)
30 (73.1)
0.34
Second flap anastomosed to primary flap (%)
7 (23.3)
11 (26.8)
0.34
Concurrent contralateral procedure (%)
6 (20.0)
15 (36.6)
0.10
Delayed reconstruction (%)
15 (50.0)
21 (51.2)
0.42
Abbreviation: IMA, internal mammary artery.
Complications were categorized as either major or minor. Major complications included
reoperation for any reason during the initial hospitalization, partial or complete
flap loss, deep venous thrombosis/pulmonary embolism, and symptomatic bulge formation.
Minor complications included wound infection or wound breakdown managed without additional
surgery, and seroma formation. Fat necrosis was diagnosed clinically and was categorized
as mild (<2 cm) or moderate (>2 cm).
The cohorts were compared head to head and comparisons were performed using the student's
t -test. A value of p < 0.05 was considered statistically significant. All reported p -values correspond to a two-sided test.
Results
The average BMI in the normal BMI group was 23.1 ± 1.3 kg/m2 , while the average BMI in the overweight/obese group was 28.9 ± 4.0 kg/m2 (p < 0.01). Age at reconstruction was similar in both groups (normal BMI = 52.8 ± 7.9,
overweight/obese = 53.2 ± 8.9; p = 0.42). The only difference in comorbidities that approached statistical significance
was in the rate of hypertension as the normal BMI patients were less likely to be
hypertensive at baseline than were the overweight or obese patients (normal BMI = 16.7%,
overweight/obese = 34.1%; p = 0.06). Diabetes was more prevalent in the overweight/obese group as well, but this
finding did not reach statistical significance (normal BMI = 3.3%, overweight/obese = 7.3%;
p = 0.25). There was no statistically significant difference in the rate of chemotherapy
or radiotherapy between groups ([Table 1 ]).
Mastectomy specimen weights were greater in the overweight/obese group than in the
normal BMI group (normal BMI = 472.8 ± 181.9 g, overweight/obese = 692.8 ± 261.1 g;
p < 0.01). Similarly, the weight of the conjoined flaps at the time of harvest, as
well as the final weight of each conjoined DIEP flap, following shaping and insetting
were greater in the overweight/obese group. Patients in the overweight/obese group
were more likely to have concomitant contralateral procedures but this difference
did not achieve statistical significance ([Table 2 ]).
Overall, the rate of major complications observed in the two groups was similar (normal
BMI = 10.0%, overweight/obese = 12.1%; p = 0.39). Three patients in each group required return to the operating room during
their initial hospitalization. There was one partial flap loss and one pulmonary embolism
in the overweight/obese group. There were no partial flap losses or pulmonary emboli
in the normal group. There were no total flap losses in either group ([Table 3 ]). The same holds true when examining only obese patients (BMI > 30, n = 8), as there was only one major complication (partial flap loss) observed in this
subgroup.
Table 3
Major complications
Normal (n = 30)
Overweight/obese (n = 41)
p -Value
Return to OR (%)
3 (10.0)
3 (7.3)
0.39
Partial flap loss (%)
0 (0)
1 (2.4)
0.20
Total flap loss (%)
0 (0)
0 (0)
NA
Pulmonary embolism (%)
0 (0)
1 (2.4)
0.19
Symptomatic bulge (%)
0 (0)
0 (0)
NA
Total (%)
3 (10.0)
5 (12.2)
0.39
Abbreviations: NA, not available; OR, odds ratio.
There was a trend toward the occurrence of more minor complications in the overweight/obese
group, but this difference did not reach statistical significance (normal BMI = 36.7%,
overweight/obese = 39.0%; p = 0.47). More wound complications at both the donor site and the recipient site were
observed in the overweight/obese group than in the normal BMI group; neither finding
reached statistical significance. More breast seromas were observed in the normal
BMI group than in the overweight/obese group (normal BMI = 13.3%, overweight/obese = 0.0%;
p < 0.01). There were no other statistically significant differences in the minor complications
between the two groups ([Table 4 ]).
Table 4
Minor complications
Normal (n = 30)
Overweight/obese (n = 41)
p -Value
Breast (%)
Wound
3 (10.0)
5 (12.1)
0.39
Hematoma
0 (0)
0 (0)
NA
Seroma
4 (13.3)
0 (0)
<0.01
Infection
1 (3.3)
2 (4.9)
0.11
Persistent edema
2 (6.7)
1 (2.4)
0.19
Donor site (%)
Wound
2 (6.7)
5 (12.2)
0.22
Hematoma
1 (3.3)
1 (2.4)
0.41
Seroma
2 (6.7)
4 (9.8)
0.32
Infection
0 (0)
0 (0)
NA
Total percentage (n )
36.7% (11)
39.9% (16)
0.47
Abbreviation: NA, not available.
Note: Certain patients experienced more than one minor complication; the total percentage
of complications reflects the number of patients who experienced at least one minor
complication.
A trend toward a higher rate of mild fat necrosis was observed in the overweight/obese
group, but this trend did not reach statistical significance. However, we did observe
a statistically significant increase in the rate of moderate fat necrosis in the overweight/obese
group ([Table 5 ]).
Table 5
Fat necrosis
Normal (n = 30)
Overweight/obese (n = 41)
p -Value
Mild <2 cm (%)
5 (16.7)
8 (19.5)
0.38
Moderate >2 cm (%)
0 (0)
4 (9.8)
0.04
Total (%)
5 (16.7)
12 (29.3)
0.12
Discussion
The incidence of major complications of approximately 10% experienced by both normal
and overweight/obese BMI cohorts who underwent unilateral bipedicle-conjoined DIEP
flap breast reconstruction was nearly identical ([Table 3 ]). This observation (∼10%) is consistent with published norms for microsurgical breast
reconstruction.[15 ]
[16 ] These findings suggest that using bipedicle-conjoined DIEP flaps for unilateral
breast reconstruction is safe across a wide spectrum of body mass indices. It is,
however, prudent to recognize that certain minor complications will likely be more
prevalent in overweight or obese patients. The overweight and obese patients in our
series experienced more frequent wound complications in their reconstructed breasts
and at their abdominal donor sites. Similarly, they were more likely to develop both
mild and moderate fat necrosis. Though only the difference in the rate of moderate
fat necrosis reached statistical significance, the observed trends suggest that one
should expect more wound complications and fat necrosis in overweight and obese patients
than in patients with a BMI ≤ 25. Higher rates of complications in patients with a
BMI ≥ 25 undergoing breast reconstruction has been well documented and is not exclusive
to any particular technique.[12 ]
[13 ]
[14 ]
[17 ] Patients should be counseled accordingly with particular attention paid to proper
risk stratification and prophylaxis for thromboembolic events using the Caprini's
Risk Assessment score.
Despite the increased prevalence of minor complications in overweight and obese patients,
we believe that the use of bipedicle-conjoined DIEP flaps for unilateral reconstruction
is of great utility in this population and that the benefits frequently outweigh the
risks.
The modern approach to reconstructing a breast in an aesthetic fashion was laid out
in a four-part series in 2009 by Blondeel et al.[18 ]
[19 ]
[20 ]
[21 ] In this series, the authors stress importance of restoring three essential elements
of the breast: the footprint, conus, and skin envelope. Adoption of approaches that
satisfy these criteria has undoubtedly led to refinements in bipedicle-conjoined DIEP
flap reconstruction for unilateral defects and to the use of four-flap solutions for
bilateral breast reconstruction.[22 ]
[23 ]
[24 ]
[25 ]
[26 ]
[27 ] Published reports suggest that these techniques have thus far been applied predominantly
to patients with a normal or low BMI. While many overweight and obese patients possess
what many surgeons would consider “adequate” abdominal tissue for standard reconstruction,
many of these reconstructions will fall short in restoring one or more of the three
essential parameters necessary to achieve an aesthetic reconstruction when only a
single pedicle flap is utilized. A three-zone single-pedicle flap may transpose adequate
tissue for reconstruction; however, it is the experience of the authors that perfusion
in this configuration is less reliable than that of a bipedicle-conjoined flap.
Patients with a higher BMI often have breasts characterized by a large volume of parenchyma
and a wide base diameter. These patients therefore have a correspondingly large breast
footprint and/or conus required to achieve an aesthetically pleasing reconstruction.
For unilateral reconstruction, it has been the experience of the senior authors that
a single pedicle DIEP flap frequently does not provide adequate skin, and soft tissue
volume, in the optimal and proportions and dimensions, to reconstruct the anatomic
elements of the breast needed to achieve aesthetically acceptable results, and/or
to match the contralateral breast, even when the contralateral breast is reduced ([Fig. 1 ]). It has therefore become the standard of practice of the authors, regardless of
a patient's preoperative BMI, to employ bipedicle-conjoined flaps to improve outcomes
in situations where a single-pedicle flap is deemed insufficient to restore the footprint
or conus ([Fig. 2 ]).
Fig. 1 This patient (BMI = 34.8) presented for delayed breast reconstruction in 2008, 3
years after her mastectomy. At the time of her reconstruction, the senior authors
did not perform bipedicle-conjoined DIEP flaps in overweight patients. As such, she
underwent unilateral reconstruction with a left DIEP flap (777 g; mastectomy weight
unknown). Despite her overhanging pannus, her reconstruction is deficient of both
volume and skin when compared with the contralateral side (even after subsequent contralateral
reduction). In the authors' current practice, this patient would be reconstructed
using bipedicle-conjoined flaps. BMI, body mass index; DIEP, deep inferior epigastric
perforator.
Fig. 2 This patient (BMI = 33.9) presented for delayed breast reconstruction following mastectomy
and subsequent radiation therapy (A ). The senior authors' preoperative assessment includes topographic surface measurements
to determine the dimension of skin required to create an adequately projected and
ptotic breast. In this case it was determined that the reconstruction would necessitate
approximately 40 cm of skin in its greatest dimension (B ). Despite the patient's large abdominal pannus, it was clear that a hemi-abdominal
flap would not provide adequate skin nor volume to allow for reconstruction to match
that of the contralateral breast. The postoperative position of the umbilical aperture
in the bipedicle-conjoined flap is illustrative in this case of how deficient of skin
a hemiabdominal flap would have been. The patient is shown following revision of her
left breast reconstruction and balancing reduction of the contralateral breast (C ). BMI, body mass index.
Overweight or obese patients that are reconstructed in an immediate fashion may require
bipedicle-conjoined flaps to restore adequate volume of the reconstructed breast ([Fig. 3 ]). The same cohort of patients reconstructed in a delayed fashion may require not
only more volume than a hemiabdominal flap may provide, but a larger area of skin
as well. Inadequate reconstruction of the skin envelope leads to flattening of the
breast and a lack of natural appearing ptosis. The senior authors therefore routinely
employ bipedicle-conjoined flaps in these cases ([Fig. 4 ]).
Fig. 3 This patient (BMI = 31.0) presented for immediate breast reconstruction. It was determined
preoperatively that she would require a bipedicle-conjoined flap to restore adequate
volume to her reconstructed breast, despite her significant pannus and a planned concurrent
contralateral mastopexy. Her left mastectomy weight was 937 g. Her bipedicle-conjoined
flap weight was 1,484 g initially and 1,026 g after trimming. She is shown postoperatively
(below) following a single revision of her abdominal donor site scar and nipple-areola
complex creation. BMI, body mass index.
Fig. 4 This patient (BMI = 39.0) presented for delayed breast reconstruction. It was determined
preoperatively that she would require a bipedicle-conjoined flap to restore both her
skin envelope and an adequate volume to create a symmetric conus, despite her significant
pannus and a planned concurrent contralateral mastopexy. Additionally, she had a prior
lower midline laparotomy that would decrease the reliability of a single-pedicle three-zone
flap. Her mastectomy weight was unknown. Her bipedicle-conjoined flap weight was 1,603 g
initially and 1,215 g after trimming. She is shown postoperatively (below) following
a single revision consisting of excision of a small area (<2 cm) of fat necrosis,
abdominal scar revision with donor site liposuction and nipple creation. BMI, body
mass index.
Conclusion
For many overweight or obese patients with unilateral reconstructive requirements,
single-pedicle flaps or implant-based reconstruction will be inadequate. Our data
demonstrate that bipedicle-conjoined DIEP flap reconstruction can be performed safely
in overweight and obese patients with morbidity on par with that observed in “normal”
weight patients. As the average BMI of women continues to increase nationally, it
is imperative that plastic surgeons expand the indications for autologous reconstruction
to parallel this demographic shift and better meet the needs of our patients.[28 ]
