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The Free Jejunum Flap

Anatomic considerations

Tissue:
Small bowel with a root of mesentery, lymphatics and vascular inflow.
Innervation:
this flap is not innervated but it retains peristalsis and must be placed ante grade if tubed to prevent peristaltic reflux.
Blood supply:
Branches from the superior mesenteric artery and accompanying vein.
Artery:
A large caliber artery at least 3 millimeters in size depending on the level of harvest of jejunal branches.
Vein: The corresponding veins are large, comparable or larger in size than the artery.
Pedicle length:
Can be dissected up to 15 centimeters in length.

Vascular Anatomy

Dissection of the Posterior Flap

The vascular anatomy of the jejunum.

The small bowel is supplied by the superior mesenteric artery (SMA). The bowel is held by the mesentery, the base of which travels from the left upper quadrant at the ligament of Treitz to the right lower quadrant and the terminal ileum. The SMA distributes more than 10 major branches to the small bowel. The second or third branch provides adequate pedicle length and length of jejunum to supply the flap.

Operative Procedure

Bowel prep is performed the night before surgery.  The patient is prepped supine, exposing and draping the abdomen.   An upper midline limited incision, below the xiphoid and above the umbilicus is used for exposure.

The Incision

An upper midline incision is used for harvest, and with limited length still affords exposure for pedicle dissection.

The transverse colon and stomach are retracted superiorly, isolating the small bowel. The ligament of Trietz defines the apex of the small bowel mesentery.  The jejunum is traced distally from this point and the branches from the superior mesenteric artery are identified.  The second or third branch to the jejunum provides a long arterial pedicle and can perfuse the territory between adjacent segments nicely. For purposes of clarity the figure below shows a larger incision and the patient's head is superior.

The Jejenum is Exposed

The flap is exposed and the mesenteric arterial and venous branches are isolated.

The mesentery on either side of the vascular segment is divided, ligating small branches. When the bowel segment is defined, it can be divided and primary anastomosis of the remaining jejunum is done with suture or staples, depending on surgeon's preference.

The Flap is Isolated

The flap is isolated and the small bowel is re-approximated.

If a reconstruction is being performed that requires a larger proximal lumen (like the hypopharynx) the anti-mesenteric border can be slightly incised to fish mouth the proximal flap.  Alternatively, if the flap is being used as a mucosal lining, and not a tube, then the entire anti-mesenteric border can be longitudinally divided, providing a large mucosal flap.

Removing the Tube Structure

For a mucosal non-tubed reconstruction the entire anti-mesenteric border can be incised to construct a mucosal sheet.

Postoperative Care

Naso gastric suction is used as needed and feeding is begun when ileus has resolved and bowel function resumes. A feeding tube can be placed during the harvest and gastric feeds begun before oral feeding if esophageal reconstruction is being undertaken.