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García Nores et al. Plast Aesthet Res 2023;10:33 https://dx.doi.org/10.20517/2347-9264.2022.146 Page 3 of 10

We strongly recommend trimming any portion of the skin paddle and/or sub-Scarpal fat that is clearly
hypoperfused during arterial phase as well as poorly draining on the venous phase evaluation. A flap with
superficially dominant venous drainage can also become apparent during this stage and should prompt the
surgeon to perform a second venous outflow anastomosis. This is supported by Hembd et al., who reported
on 506 DIEP flaps with decreased odds of fat necrosis with the use of indocyanine green angiography,
without a reduction in flap failure rates. Overall incidence was 13% and the use of ICG was independently
associated with a decrease in the odds ratio . Similarly, Momeni also reported a series of 80 patients, 137
[10]
flaps, and an overall incidence of 14.6% of fat necrosis. ICG angiography was used to guide debridement in
one cohort, reducing the incidence of fat necrosis from 18/79 to 2/58 . Another group similarly
[11]
demonstrated a decreased rate of fat necrosis from 59.5% to 29% with ICG as well as a reduced rate of
[12]
second surgery from 45.9% to 20.8% . Parmeshwar et al. performed a systematic review of the use of ICG
angiography. Based on the analysis of 9 articles and a comprehensive review involving a total of 355 patients
and 824 free flaps, the researchers concluded that there was a significant disparity in flap fat necrosis, but no
difference in total or partial flap loss. They suggest that ICG angiography is a more effective and efficient
[13]
technique to reduce fat necrosis and is more sensitive than clinical assessment . However, most recently,
Yoo et al. reported their experience with 353 DIEP flaps, revealing a 10.9% incidence of fat necrosis and no
difference with the use of ICG angiography . Other less common intraoperative imaging techniques
[14]
include Doppler, dynamic infrared thermography, and hyperspectral imaging.

Perforator selection (Medial vs. lateral)
Saint-Cyr has published numerous studies on the perforasome theory, which help us understand and
[15]
maximize flap perfusion. He reports the majority of perforators are located in the periumbilical region .
However, this eccentric location has led other authors to question whether the medial row perforators were
indeed the optimal choice. Kamali et al. reported a nearly 3-fold higher incidence of fat necrosis in flaps,
based solely on the medial row vs. lateral row (24.5% vs. 8.2%) and no difference with flaps based on lateral
only vs. both medial and lateral. They suggested increasing the number of perforators harvested along the
[16]
same row to minimize fat necrosis . However, Garvey et al. reviewed 228 patients with 120 medial and 108
lateral perforator flaps with similar rates of fat necrosis and partial flap necrosis . In another study by
[17]
Saint-Cyr, he offered further insights into the zones of perfusion based on medial vs. lateral row and effects
on flap harvest and design. The authors reported that lateral row perforators rarely crossed midline so
unilateral DIEP flap which require more than hemi-abdominal volume should be harvested based on medial
[18]
row perforators . Lastly, Hembd et al. reviewed 409 DIEP flaps and noted an incidence of 14.4% fat
necrosis with a decrease in the odds ratio for this endpoint when using lateral row, or both medial and
lateral row perforators. They recommend using larger caliber perforators and lateral row perforators alone,
or in addition to medial row perforators, rather than just harvesting more perforators due to the increased
[19]
risk of abdominal bulge .
Number of perforators
To minimize donor site morbidity, the surgeon often strives to minimize the number of perforators
harvested while maintaining adequate flap perfusion. Khansa et al. reported the most important predictor of
fat necrosis was flap type, with the lowest degree of fat necrosis in the Free TRAM flaps (6.9%), then the
SIEA flaps (8.1%), followed by the pedicled TRAM (12.3%), and finally the DIEP flap at 14.4% . A 2010
[1]
study by Baumann et al. found less fat necrosis in msTRAMs or multiple perforator DIEPs than single
perforator DIEPs. The lowest incidence of fat necrosis was actually reported in flaps with 3-5 perforators
(predominantly msTRAMs) . Their findings were validated by Garvey et al. . Bhullar et al. also
[21]
[20]
concluded that medial row perforators had a wider perfusion zone and suggested harvesting at least 2-3
perforators of substantial caliber . Both Wu and Saint-Cyr reported increased rates of fat necrosis in
[22]
single-perforator DIEP flaps by 3-fold and 2-fold, respectively [23,24] . However, it is well known that increasing