Transverse Rectus Abdominis Myocutaneous Flap and Vertical Rectus Abdominis Myocutaneous Flap

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Transverse Rectus Abdominis
Myocutaneous Flap and Vertical
Rectus Abdominis Myocutaneous Flap

Muscle flaps play a large role in pelvic reconstruction of the female patient who has had radical resection for malignant disease, particularly when associated with total pelvic irradiation. They offer the advantage of bringing a non-irradiated tissue with a non-irradiated blood supply into the pelvis for coverage of defects. The rectus abdominis muscle with its unique blood supply coming from the inferior epigastric vessels, right or left, and the anatomy of the vessels in the rectus abdominis muscle allow a muscle flap to be based on a long muscle pedicle with excellent blood supply. The transverse rectus abdominis myocutaneous (TRAM) flap and the vertical rectus abdominis myocutaneous (VRAM) flap have the smallest incidence of necrosis of any of the myocutaneous flaps associated with pelvic reconstructive surgery.

Physiologic Changes. The physiologic change is that an open wound has been covered with a myocutaneous or muscle flap that offers an excellent covering for a wound and, at the same time, brings in a muscle with an excellent blood supply, i.e., the inferior epigastric artery, a branch of the external iliac artery.

Points of Caution. The paddle-shaped skin flap should not be separated from the anterior rectus fascia in order to preserve the perforator vessels from the muscle to the skin. Extreme care should be taken to ensure the integrity of the inferior epigastric vessels as they branch off the external iliac vessels. When the neurovascular bundle of the inferior epigastric artery has been interrupted, it would be extremely unusual for the VRAM flap to survive.

Technique

The abdominal wall shows the VRAM flap and the TRAM flap.

The VRAM flap is outlined. The rectus abdominis muscles are seen ghosted beneath the skin. The incision is noted. The skin island is designed appropriate to the defect to be filled within the pelvis.

After the incision has been made along the medial border of the rectus fascia and the skin island is noted toward the superior portion of the proposed flap, the external oblique fascia, the lateral and medial borders of the fascia, is noted. The linea alba is seen. The left rectus abdominis muscle is ghosted under the rectus fascia. The incision follows a second incision in the rectus fascia and is outlined as above, keeping intact a 5-cm width of rectus fascia to be taken with the flap. This ensures that the perforators coming off the anterior surface of the muscle through the rectus fascia are not interrupted or damaged. The inferior epigastric vessels are shown ghosted on the lateral portion of the rectus muscle.

A cross section looking cephalad from beneath the flap is shown. The skin island is cut at an angle to preserve blood supply to the surface of the skin. The rectus muscles are shown. The posterior rectus fascia is left intact; the muscle is dissected off the posterior rectus fascia. By not sacrificing the posterior rectus fascia, reduction in hernias is noted.

The VRAM flap has been completed, the posterior rectus fascia is noted, and the small perforators coming off the posterior rectus fascia are ligated. The rectus muscle is transected at the pubic symphysis area. The entire muscle with its sheath of rectus abdominal fascia on the anterior portion of the muscle is intact. The skin island is now ready for rotation through the defect made in the posterior rectus fascia above the symphysis pubis to bring this into the pelvic area. The medial border of the right rectus muscle has been shown. The lateral border of the right rectus fascia is also noted.

The entire rectus muscle is lifted out of its fascia covering then rotated 180° and mobilized inferior through the posterior fascia into the pelvic cavity. The blood supply is coming exclusively through the inferior epigastric artery, and the perforators are coming through the muscles as shown in Figure 4.

The VRAM flap is now pulled through the abdominal cavity into the pelvis and will be brought out to cover the vulvoanal defect noted in this particular patient. Modifications can be made to cover the exact limits of the defect noted in specific patients.

The TRAM flap is made in a paddle-shaped manner from one anterior superior iliac spine to the opposite anterior superior iliac spine. The rectus abdominis muscle can be seen beneath the rectus fascia. Note that the right rectus abdominis muscle has been preserved in this particular case. The dissection is made underneath the anterior rectus fascia, which is preserved in a transverse fashion.

The TRAM flap is supported by the left inferior epigastric muscles. Note that the left rectus muscle has been brought out of its fascia enclosure, preserving the anterior rectus fascia for 5 cm on each side of the muscle. The dotted line across the tip of the paddle is usually ischemic and can be proven so by the fluorescein and Wood's lamp test. Most of this usually has to be sacrificed.

In this cross section of the TRAM flap looking caudad from above, the posterior rectus fascia is left intact. The inferior epigastric vessels are shown entering the rectus muscle. The right rectus muscle remains intact. The perforators coming off the anterior rectus fascia have been ligated. The skin is cut at an angle. The right side of this skin flap may have to be sacrificed if it is shown to be ischemic under the Wood's lamp with fluorescein dye injection.

The TRAM flap is entering the abdominal cavity through an incision in the posterior rectus fascia. It can be brought down through the space of Retzius when the bladder has been removed, or if the bladder is in place, it can be brought down through the space of Retzius through the urogenital diaphragm and into the vagina for a variety of purposes.

The anterior rectus fascia is closed up to the point of no tension. At this point, a synthetic mesh can be introduced into the defect and sutured into place.

The skin is closed with stainless steel staples.