Anatomical Landmarks for Safe Elevation of the Deep Inferior Epigastric Perforator Flap: A Cadaveric Study

METHODS

Ten fresh cadaveric hemi-abdomens were dissected with the aid of loupe magnification. In this study, there were 4 male and 6 female specimens. Initial measurements were taken from the umbilicus to the xiphoid and the pubic symphysis. Through a midline abdominal approach, adipocutaneous flaps were elevated beyond the lateral border of the rectus muscle. The anterior rectus fascia was then incised along the lateral edge of the rectus muscle, and the DIEA was identified as it entered the lateral edge of the rectus muscle (Fig 1). Measurements were taken from the vertical height of this junction, the DIEA-RAM-junction (DRJ), to the umbilicus. Dissection proceeded with the elevation of the rectus muscle, the DIEA, and its perforators along the posterior aspect of the muscle (Fig 2). The first perforator of the DIEA was identified at the anterior rectus fascia layer and dissected down to its DIEA origin (Fig 3). Again, measurements were taken from the vertical height of the perforator to the umbilicus. In addition, transverse measurements were taken from the umbilicus to the lateral edge of the rectus and to the DIEA.

Figure 1. A dissection of the rectus muscle, the deep inferior epigastric artery (DIEA) rectus junction (DRJ), and the DIEA. Note the location of where the DIEA enters the rectus muscle.

Figure 2. A dissection of the posterior aspect of the rectus muscle and the DIEA and its branching pattern.

Figure 3. A dissection with the perforators marked.

RESULTS

The average distance from the xiphoid to umbilicus was 18.2 ± 1.27 cm. The distance from the umbilicus to pubis was 14.9 ± 2.3 cm. The vertical distance from the umbilicus to the DRJ was 10.45 ± 1.58 cm, and the vertical distance from the level of the umbilicus to where the first DIEA perforator traverses the RAM was 7.4 ± 1.64 cm (Table 1).

Distance ratios were then calculated for the DIEA and its first perforator. The distance between the umbilicus and the DRJ corresponds to approximately 0.7 times the distance between the umbilicus and the pubic symphysis. Similarly, the distance between the umbilicus and the first perforator corresponds to approximately 0.5 times the distance between the umbilicus and the pubic symphysis (Table 1). Additional analysis demonstrated consistent findings with regard to distance ratios for each specimen individually.

DISCUSSION

The reconstructive surgeon is constantly challenged to investigate and develop techniques to improve functional and aesthetic outcome. Utilizing the DIEP flap for breast reconstruction provides appropriate aesthetic outcome while preserving abdominal wall function.¹¹

The burden to the surgeon typically lies in planning out the flap harvest and elevating the flap with its pedicle. Bony landmarks of the xiphoid and pubis are easily identified. The midline and lateral edges of the rectus muscle and umbilicus can usually be palpated and inspected. We used these bony and soft tissue landmarks in conjunction with our findings to develop normalizing ratios to best determine where the DIEA crosses the rectus muscle and where the first perforator penetrates through the anterior surface of the rectus.

Variance in patient size can be corrected by using vertical distance ratios. For example, we noticed that female specimens had relatively shorter abdomens as represented by an average vertical height of 31.5 cm from the xiphoid to the pubis. On the other hand, male specimens have an average vertical height of 34.2 cm. Despite variations in patients' height, the individual distance ratios calculated for each specimen group were consistent with our overall distance ratios.

After measuring the umbilicus to pubis distance, the surgeon can utilize these ratios to predict the location of the DIEA and its first perforator. The DIEA crosses the rectus at approximately two thirds of the distance between the umbilicus and pubis and the first perforator can reliably be located at one half of this distance (Fig 4).

Figure 4. A schematic demonstrating the location of the deep inferior epigastric artery (DIEA), DIEA rectus junction (DRJ), and first perforator. Note the average distance from the umbilicus to the level of the first perforator and DRJ.

These distance ratios can also be used for harvesting a rectus muscle flap, a pedicled TRAM, or free TRAM flap. Traditionally, a fascial incision and extensive dissection along the lateral border of the muscle may be necessary to determine the location of the DIEA as it courses below the rectus muscle. The distance ratios described in this study can significantly enhance our ability to dissect and divide the flap inferiorly while avoiding injury to the DIEA system.

CONCLUSION

Knowledge of anatomical landmarks can aid the surgeon in more efficiently harvesting the DIEP flap. We found that using longitudinal measurements between the umbilicus and the pubic symphysis along the abdominal midline can aid clinicians in predicting the location of the DIEA and its first perforator. These measurements are coupled with distance ratios to correct for variance in patient size. We anticipate that this study will decrease the need for extensive intramuscular dissection, associated morbidities of hernia, bulge, and denervation.

REFERENCES