Skin and fat from the lower abdominal wall. Usually only a hemi-abdomen is perfused. If both sides of the abdominal skin paddle are needed, the contralateral artery and vein may need to be harvested as well.
Intercostal nerves T11 and T12 dermatome via deep perforators. Not harvested as a sensory flap.
Blood supply: The superficial inferior epigastric artery and venae. A larger more superficial vein is almost always present.
Artery: Usually small caliber, up to slightly larger than a millimeter if you are lucky.
Vein(s): The venae are only occasionally large enough for repair. The more superficial and more medial vein is typically large enough for microsurgical repair.
Pedicle length: Up to 5 centimeters long at best.
The SIEA flap can be used for a variety of reconstructive procedures when a large segment of soft tissue, including fat and skin is necessary. It has recently become more popular for breast reconstruction, but the presence of superficial epigastric blood vessels that nourish the flap is variable. Although there are advocates of preoperative imaging studies, the true presence of these vessels can only be determined intraoperatively. If not found, the surgeon must be prepared to harvest an alternate flap, which in breast reconstruction is more commonly the DIEP flap.
The superficial inferior epigastric artery arises from the femoral artery, below the inguinal ligament. The vessel travels in the subcutaneous fat of the inferior abdomen and spreads out to supply the hemi-abdomen. In some patients, a single artery and draining vein can supply the bulk of the lower abdomen zones 1 to 4.
The SIEA flap is perfused by the superficial inferior epigastric artery. Draining is via the superficial inferior epigastric vein, and vein that is distinct from the typically small venae of the artery.
The patient is prepped and draped supine. Marking can be done preoperatively in the upright position, to identify any natural suprapubic crease and to mark the anterior superior iliac spines. With the patient recumbent and the knees flexed, the abdominal tissue can be pinched to determine the tightness of postoperative closure. The superior incision reaches above the umbilicus, and laterally to the axis of the anterior superior iliac spines. The flap is separated from the umbilicus with a periumbilical incision (marked in blue below), leaving the stalk attached to the abdominal wall. When the abdomen is redraped, the umbilicus is brought through an new incision.
The inferior abdominal incision is made first, and the presence of the artery and vein are confirmed.
The inferior incision is made first on either side, depending on anatomic needs. The vein is usually quite superficial, and care must be taken not to injure it during the incision. The artery is found slightly deeper and more laterally. The vessels are dissected inferiorly to assess the adequacy of their diameter. The ipsilateral hemi-abdominal flap is elevated. If a DIEP flap is being considered, perforators are found and the largest is preserved. If the SIEA vessels are adequate and the surgeon can commit to this flap, the perforators from the DIEP system can be ligated.
Once the vessels are confirmed to be present and of adequate caliber, flap dissection proceeds quickly. the flap is elevated superficial to the rectus sheath, and perforators from the deep inferior epigastric system can be ligated.
The contralateral flap is elevated and the SIEA vessels from this side are preserved if needed for a large bipedicle flap. The vein can be preserved if venous drainage appears to be an issue.
A contralateral superficial vein can be taken if a large flap is necessary and alternate venous drainage is desired.
The flap is raised on the SIEA vessels. Before blood vessel division, the circulation of the contralateral flap is assessed and any tissue that suffers from arterial or venous insufficiency can be discarded.
The area that is well perfused can be defined in situ before the flap is divided. It is typical for a flap this size to require some trimming of poorly perfusing tissue.
The donor site is sutured closed in layers over two suction drains. The abdomen is flexed during closure in a semi-Fowler position and the patient maintains a flexed position for several days before standing fully erect.