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Chen et al. Plast Aesthet Res 2023;10:24 https://dx.doi.org/10.20517/2347-9264.2022.136 Page 3 of 26

Hematology for risk optimization and operative clearance. Typically, a prophylactic regimen of either an
injectable low molecular weight heparin (LMWH) or an oral, direct factor Xa inhibitor is recommended for
1-4 weeks postoperatively. All patients are placed on heparin prophylaxis intraoperatively.

Obesity
Obesity in patients undergoing microsurgical breast reconstruction has been associated with increased risks
of partial flap necrosis, fat necrosis, and venous congestion [15-17] . In a study of 936 free transverse rectus
abdominis muscle (TRAM) flap cases, Chang et al. found that obese and overweight patients had a
significantly higher overall flap complication rate of 39.1% (compared to 20.4% among normal-weight
patients), which included a total flap loss, hematoma, seroma, and skin necrosis . Notably, they did not
[18]
find any difference in the rate of vessel thrombosis. Hanwright et al. found similar results in their analysis of
free flap breast reconstruction cases taken from the American College of Surgeons National Surgical Quality
Improvement Program (ACS-NSQIP) database . When classified into class I (BMI of 30 to < 35), class II
[17]
(BMI of 35 to < 40) and class III (BMI ≤ 40) obesity, Fischer et al. found that class III obesity patients had
significantly higher rates of flap loss and trended toward higher rates of intraoperative arterial
[19]
thrombosis . Similarly, Schaverien et al. found that class III obesity was associated with a significantly
higher risk of complete flap failure, donor-site complications, and overall complications .
[20]

Given the increased risk of complications associated especially with morbid obesity, careful patient selection
is necessary and patients with class III obesity may be advised to reduce their weight prior to surgery .
[19]
While no studies demonstrate a specific BMI that provides an acceptable risk to proceed with surgery,
statistically significant differences in complications tend to increase proportionally as BMI increases . In
[21]
our practice, we do not use a specific BMI cutoff to assess surgical candidacy, but we candidly discuss the
increased risks of partial or total flap failure with all class III patients seeking microvascular breast
reconstruction.

Tobacco use
Despite experimental evidence on the detrimental effects of tobacco smoke exposure on thrombogenicity,
clinical studies on free flap transfers in breast reconstruction have demonstrated conflicting results, with the
majority suggesting a less significant effect [22-24] . Khouri et al. found that there was no significant effect of
[25]
tobacco use on flap outcome . Masoomi et al. and Arnez et al. found no significance in flap loss or vascular
thrombosis rates in smokers compared to non-smokers [7,26] . Despite studies showing a weak association
between flap thrombosis and smoking, patients should still be advised to cease smoking a minimum of 3
[27]
weeks prior to surgery, a widely advocated practice due to the established risk of poor wound healing .

Radiation
Patients seeking breast reconstruction following post-mastectomy radiation therapy have become
increasingly common. Although radiotherapy is known to impair wound healing, its effect on
[28]
microanastomoses remains an area of ongoing study . Findings from animal studies on irradiated
microanastomoses have been variable, with some demonstrating significant change in patency due to
intimal hyperplasia as well as increased thrombosis risk, and others showing no such effects [29-32] . Fracol et
al. and Fosnot et al. found a significantly higher risk of any intraoperative vascular complication in radiated
fields compared to non-radiated fields, but no significant differences in arterial or venous thrombosis rates
both intra- and postoperatively, and no overall difference in the rate of flap loss associated with
radiation [33,34] .