Keywords
microsurgery - breast reconstruction - anatomy
Introduction
As a mainstay of autologous breast reconstruction, the deep inferior epigastric artery
(DIEA) perforator (DIEP) flap and its vascular anatomy have been well studied. The
DIEA, originating in the majority of cases from the external iliac artery, provides
the blood supply to the skin and soft tissues of the lower abdominal wall.[1] Preoperative imaging with computed tomography angiography (CTA) has become routine
practice in many centers for DIEP flap planning, and provides accurate assessment
of the vascular anatomy, which varies widely across patients. This has allowed safer
intraoperative dissection, and translated to reduced operative time and improved overall
flap outcomes.[2]
[3] From its origin on the external iliac artery, the DIEA courses superomedially toward
the lateral edge of the rectus sheath before approaching the deep aspect of the rectus
abdominis. At this point, the path of the artery can be understood in multiple segments:
the DIEA course deep to the rectus abdominis muscle, the intramuscular course of the
DIEA, the intramuscular course of the DIEA perforator, the perifascial course of the
perforator, and the subcutaneous course of the perforator.
Several papers to date have described their encounter with an anomalous “epiperitoneal”
or “peritoneo-cutaneous” perforator during the raising of a DIEP flap for breast reconstruction,[4]
[5]
[6] a perforator that pierces the posterior rectus sheath from a peritoneal origin,
to traverse rectus abdominis and supply the DIEP flap integument. With the increasing
sensitivity of imaging, imaging of this anatomy has improved, and we report a further
variant on this aberrant vascular anatomy, that of multiple peritoneo-cutaneous perforators
providing supply to the abdominal wall, and present this in the context of DIEP flap
harvest.
Idea
Lasso et al[4] described the presence of a single large medial periumbilical perforator that was
found to pierce deep to the posterior fascia, and found to augment the blood flow
to their DIEP flap. Whitaker et al[6] further investigated this anomaly in a series of cadaveric dissections and CTA analyses,
confirming the presence of a significantly sized peritoneo-cutaneous perforator supplying
and draining the abdominal wall in approximately 1% of patients in their study. These
perforators were seen to have no communication with the DIEA. These studies identified
single large perforators in their cases. The current study comprises a case report
and context of this case within our clinical experience. All CTAs described herein
were performed at a single institution, using a standardized 128-slice CTA scanner
and single protocol for scanning. Each CTA scan was reported by a single person, using
Horos (The Horos Project, Nimble Co LLC Purview, Annapolis, MD) to map out each perforator
incorporated within the abdominally based flaps planned. The data presented comprises
a consecutive series, with no exclusions.
Institutional human research ethics committee approval was achieved (approval numbers
2006.038; 2006.231 and HREC86700PH-2022), and full informed patient consent was undertaken.
We thus describe the case of a 48-year-old female who underwent abdominal wall CTA
as part of routine preoperative workup for DIEP flap breast reconstruction. Preoperative
analysis of CTA images revealed the presence of multiple bilateral peritoneo-cutaneous
perforators, a unique finding, as described above. In the course of over 3,000 CTA
assessments of the vascular anatomy of the abdominal wall, we have encountered dominant
peritoneo-cutaneous perforators in 1% of cases, matching the findings of Whitaker
et al. However, smaller such perforators have been seen in many more cases than this,
approaching 5% of cases. These perforators share some anatomical features, highlighted
in [Table 1], highlighting that these are largely periumbilical and medial row in location. In
all cases, there appeared to be no effect on DIEA perforators, with adequate DIEA
perforators able to be selected and utilized for flap harvest.
Table 1
Anatomical features of peritoneo-cutaneous perforators in 3,000 breast reconstruction
cases
|
Anatomical feature
|
Number of cases
|
|
Size > 1 mm
|
30 (1% incidence)
|
|
Size > 0.5 mm
|
150 (5% incidence)
|
|
Dominant perforator medial row
|
28/30 (93%)
|
|
Dominant perforator lateral row
|
2/30 (7%)
|
|
Dominant perforator located periumbilically
|
28/30 (93%)
|
In our case of multiple bilateral peritoneo-cutaneous perforators, it was found that
all perforators identified were periumbilical and shared no anastomoses with the DIEA
perforator system ([Fig. 1]). The DIEAs originated on either side from the obturator arteries, but otherwise
followed a standard course, giving off large medial row perforators that appeared
suitable for a perforator flap. These peritoneo-cutaneous perforators identified on
preoperative imaging were confirmed intraoperatively ([Fig. 2]). During initial flap dissection and raising, multiple perforators supplying the
lower abdominal wall bilaterally were seen to originate deep to the posterior rectus
sheath. The course of the largest of these perforators was dissected, and was confirmed
to traverse the extraperitoneal fat, posterior rectus sheath, rectus abdominis muscle,
and subcutaneous tissue, and had no direct communication with the DIEA. Ultimately,
bilateral DIEP flaps were raised bilaterally, and all identified peritoneo-cutaneous
perforators were clipped and ligated, with successful flap transfer and no complications.
Fig. 1 Computed tomographic angiogram (CTA) axial slices demonstrating a peritoneo-cutaneous
perforator (blue arrows).
Fig. 2 Intraoperative photograph demonstrating three large peritoneo-cutaneous perforators,
all over 1 mm in diameter.
Discussion
Peritoneo-cutaneous perforators are an uncommon anatomical variant in the arterial
supply of the abdominal wall. Significantly sized peritoneo-cutaneous perforators
are thought to occur in about 1% of patients,[6] though the presence of smaller perforators may be more frequent than otherwise thought.
In our case, however, there were in fact multiple large peritoneo-cutaneous perforators
bilaterally, several of which were over 1 mm in diameter. It is critical to recognize
these peritoneo-cutaneous perforators preoperatively to avoid mistaking them for a
DIEA perforator during the raising of a DIEP flap, should they be present. Alternatively,
they may also be used as a second perforator to augment blood flow to a DIEP flap.[4]
Innumerous small peritoneal branches from the entire DIEA provide supply to the parietal
peritoneum concordant with its cutaneous territory.[7] This is the anatomical basis for the composite musculo-peritoneal free flap.[8] However, Whitaker et al demonstrated these peritoneo-cutaneous perforators to be
separate to the DIEA system by directly injecting contrast mixture in the perforators
found in their cadaveric study. Peritoneo-cutaneous perforators may be considered
an example of abnormal vasculogenesis. While it has been long held that the umbilicus
receives supply from intra-abdominal vessels, it is conceivable that the periumbilical
perforators that originate intra-abdominally represent a developmental abnormality
whereby umbilical vessels have developed a more extensive pattern of supply.[9]
[10] These are vessels that run within the ligamentum teres and the median umbilical
ligament, which normally contribute and anastomose with the periumbilical vascular
plexus.
Preoperative CTA has already been proven to be a useful adjunct by reducing operative
times and allowing safer intraoperative flap dissection.[2]
[3] The routine use of preoperative CTA enables the safe identification of individual
vascular anatomy and indeed the presence or absence of any significant peritoneo-cutaneous
perforators.
