The SIEA flap is very similar to the DIEP flap procedure. Both techniques use the lower abdominal skin and fatty tissue to reconstruct a natural, soft breast following mastectomy.

The main difference between the SIEA flap and the DIEP flap is the artery used to supply blood flow to the new breast. The SIEA blood vessels are found in the fatty tissue just below skin whereas the DIEP blood vessels run below and within the abdominal muscle (making the surgery more technically challenging). While the surgical preparation is slightly different, both procedures spare the abdominal muscle and only use the patient's skin and fat to reconstruct the breast.

Rates will be tabulated and drainage volumes will be measured during regular followup appointments with the care team (1 week post-op, 2 weeks post-op, 6-8 weeks post-op, 3 months post-op).

Partial flap loss defined as tissue loss greater than 10 percent of the flap or fat necrosis greater than 5cm in diameter. Total flap loss will also be assessed. These assessments will be done during regular followup appointments with the care team (1 week post-op, 2 weeks post-op, 6-8 weeks post-op, 3 months post-op)

Defined as necrosis or wound dehiscence resulting in an open wound. Will be assessed with calipers. This will be assessed during regular followup appointments with the care team (1 week post-op, 2 weeks post-op, 6-8 weeks post-op, 3 months post-op)

Intra-operative data is also being collected with the intention of using it to identify any variables of the DIEP and SIEA procedures associated with the breast and abdominal outcomes being assessed in the study. The intra-operative data being collected includes whether or not the superficial inferior epigastric vessels are present in both treatment groups. If the vessels are present, it is recorded whether or not they are of sufficient calibre to support an SIEA flap. This information is to show how many patients enrolled would be candidates to receive the SIEA procedure had they not been randomized to a treatment group pre-operatively. The size of the SIEA/DIEA at the femoral artery/external iliac artery and the size of the SIEV/DIEV at the femoral vein/external iliac vein is also recorded, along with the size of the venous coupler used to anastomose the donor and recipient vein. Other intra-op. data is being collected as well.

Patients are examined in the plastic surgery department both in the supine and upright positions for asymmetric positioning of the umbilicus, abdominal wall asymmetry, lower abdominal bulging, hernias and abdominal wound breakdown (post- operatively using calipers). Any pre-existing scars are also noted to see if this affects complication rates. This clinical examination is completed pre-operatively by the operating surgeon and during the regular follow-up appointments (1 week, 2 weeks, 6-8 weeks, 3 months post-op) by the head nurse, who has been instructed to do these assessments on every patient receiving DIEP or SIEA breast reconstruction. She therefore, does not know who is actually enrolled in the study.