The DIEP flap is based on the perforators of the deep inferior epigastric artery (DIEA), which arises from the external iliac artery. The DIEA courses above the inguinal ligament on a medial oblique angle to pierce the transversalis fascia and course for a variable length on the deep surface of the rectus abdominis muscle before becoming intramuscular and giving off perforators to the overlying fat. There are 3 branching patterns of the DIEA, type 1 (29%) in which it ascends as a single trunk, type 2 (57%) in which the artery bifurcates, and type 3 (14%) in which it trifurcates. Medial row perforators will better supply the flap across midline and may sacrifice less abdominal strength as the lateral muscle and nerves are undisturbed. However, they have a longer intramuscular course, which can make the dissection more challenging.

Preoperative computed tomography (CT) or magnetic resonance (MR) angiography can ensure a patient’s candidacy for the DIEP flap, particularly in the context of previous abdominal surgery. Imaging can also identify a dominant perforator or row to target in the dissection, increasing operative efficiency.

The DIEP flap is marked with the patient standing or lying in a beach chair position. The upper horizontal line can be drawn up to 2 cm above the umbilicus or lowered based on perforator mapping. Each anterior superior iliac spine (ASIS) is then marked. The lower line is marked after asking the patient to relax the abdomen and pinching to ensure closure will be possible. Ideally, this line falls at or below the suprapubic crease. The upper and lower lines can then be connected either in the shape of an ellipse tapering at the ASIS, or a boat, in which the top line is straight and the lower curves up to meet it. The latter is favorable in patients with a deep waist, which may otherwise be blunted. The lower marking can be confirmed intraoperatively by undermining the upper flap first, and then flexing the table to confirm the point to which it can be redraped safely ( Fig. 3 A–D ).

( A ) A 40 year old female patient with right breast cancer ( B ) Preoperative markings of right mastectomy, left DIEP flap for right breast reconstruction and right smaller DIEP flap for contralateral balancing augmentation. ( C ) Harvested DIEP flaps. ( D ) One year postoperative result of right DIEP reconstruction with 3 dimensional right nipple tattoo and left balancing autologous DIEP augmentation.

Beveling below Scarpa’s fascia at the superior incision can capture more fat volume and superior perforators but care must be taken not to create a donor site contour abnormality. The native upper abdominal flap is undermined to the xyphoid process and costal margins. At the inferior incision, the superficial system (superficial inferior epigastric artery/vein [SIEA/V]) should be visualized, dissected out, and clipped for possible use. If planning to anastomose the SIEV, a length equal to the thickness of the flap or greater should be preserved.

Laterally, dissection can be carried out swiftly with monopolar until the white fascia of the rectus sheath is crossed. For bilateral cases, once the umbilicus is isolated, and the flap can be split at the midline immediately to allow for excellent visualization of medial and lateral row perforators on both sides to identify the dominant perforator(s). Approach of the medial row should be done cautiously as perforators can lie close to the umbilicus and midline, and the midline splitting incision may be slightly offset. When selecting a perforator, attention should be paid to the caliber and Doppler flow of the veins. Most perforators will have sufficient arterial inflow to supply the flap, but insufficient venous drainage should be avoided.

The pedicle is then dissected until it exits its intramuscular course and is on the undersurface of the rectus abdominis, either for at least 8 cm total length, or down to the deep inferior epigastric artery/vein (DIEA/V) origin. Care should be taken to preserve motor nerves. The pedicle can be passed beneath preserved nerves once fully dissected and divided. To obtain maximal length on the pedicle, it is useful to press down on the abdominal contents, either with 2 Deaver retractors or manually, while a Richardson or similar right angle retractor is pulled caudally to visualize the DIEA/V down to its origin.

To limit abdominal wall weakness and morbidity, the fascial incision should be limited to what is necessary for visualization, and motor nerves and muscle spared. Morbidity of the fascial incision increases below the arcuate line due to the convergence of the external and internal oblique with the anterior rectus sheath. If a significant amount of muscle or motor nerves have been disrupted, an inlay or retrorectus mesh should be considered to reinforce the abdominal wall and prevent bulging. Any hernias or rectus diastasis should be repaired. Progressive tension sutures can be considered as an adjunct or alternative to abdominal drains.

Optimizing the abdominal donor site is a key area of growth even for advanced breast microsurgeons. The waistline can be maintained with plication, corsetplasty, and use of a boat-shaped flap pattern. Umbilicus cosmesis can be optimized in patients with thin abdominal flaps by anchoring the umbilicus to the abdominal fascia to create depth. Creating a neoumbilicus by anchoring the dermis to the abdominal fascia can also produce an esthetic result. The Scarpa’s fascia should be approximated centrally in the abdominal closure to decrease tension on the abdominal scar and anchoring of the mons can be incorporated. Lateral standing cone deformity (dog ears) can be avoided by extending the incision lateral and working redundancy in medially. Ultimately, secondary revision may be desired.

In a bilateral case, the cosurgeon model is useful to decrease operative time. In patients with obesity, more than one perforator may be taken to prevent fat necrosis and the weight of the larger flap should be considered during inset. A long pedicle should be harvested to allow for ptosis without traction, and the breast pocket should be adequately dissected to limit pressure on the flap. The donor site should be closed without tension to prevent dehiscence, and a cuff of tissue should be left on the umbilicus to prevent devascularization.

During inset, the relationship of the breast envelope and mound is different in immediate and delayed cases. The delayed pocket is generally maintained superiorly and the native inferior mastectomy skin is de-epithelialized to allow for flap inset directly onto the inframammary fold to maintain the breast esthetic unit. In immediate cases with a large or ptotic envelope, it is often necessary to tack the flap to the chest wall to prevent pedicle shearing and reconstitute the breast footprint to produce an esthetic shape. ^,

The markings and positioning for robotic-assisted DIEP are the same as for the traditional DIEP. Targeted perforators should be anticipated and marked. The flap is elevated until the desired perforators are isolated. The fascia is entered in the usual manner and the perforator dissected along its intramuscular course until the posterior sheath is reached ( Fig. 4 A, B ). In contrast to the traditional DIEP, the superior extension of the pedicle should be preserved so that it will perfuse the flap after the pedicle is clipped intra-abdominally, so that ischemia time can be postponed until the peritoneum is closed, the robot is undocked, and the recipient site is ready for flap inset. For bilateral robotic DIEPs, both open perforator dissections are carried out prior to bringing the robot into the field and both pedicles are divided and peritoneum closed before the robot is undocked. The microvascular anastomosis is carried out on the first side while maintaining the superior extension of the pedicle of the second flap until it is ready for transfer.

( A ) Typical port configuration for the robotic portion of the DIEP flap harvest. ( B ) A 3 cm fascial incision from robotic DIEP harvest.

Once both flap pedicles have been dissected to the submuscular plane, intraperitoneal access should be established. This can be achieved with either an open Hassan or Veress needle. The AirSeal port or other insufflation system is inserted, and pneumoperitoneum should be established at 15 mm Hg. The camera is then placed through this port. Three additional 8 mm robotic ports should then be placed into the abdomen under direct visualization. If harvesting a single flap, ports should be oriented toward the contralateral side, midway between the anterior axillary line and the ASIS. The middle port is placed between these two. If harvesting bilateral flaps, the ports should be placed in a similar manner to robotic transabdominal preperitoneal repair for inguinal hernia repair, with the camera placed a few centimeters above the umbilicus and 2 lateral ports placed just lateral to the semilunar line. With this approach, a single docking can be used to harvest the left and right pedicle. This approach can also be used for unilateral flaps.

A combination of monopolar scissors and the fenestrated bipolar graspers is then used to dissect the DIEP pedicle intra-abdominally. The robotic dissection begins by identifying the external iliac source vessels. The peritoneum is incised where the DIEA is identifiable through the peritoneum, and the DIEP vessels are dissected from distal to proximal. Side branches are either clipped using microclips or ligated with a bipolar or vessel sealer as encountered.

The pedicle is circumferentially (360°) dissected from its takeoff to the point at which the dissection connects to the previously performed open dissection. The pedicle is then clipped or vessel sealed and divided distally. It is retrieved through the external fascial access. With the pedicle externalized, the peritoneum and posterior rectus sheath are closed with robot assistance. Typically, a running barbed suture is used. The robot can then be undocked and the port sites closed with figure of 8 sutures.

Once the robot is undocked and the recipient vessels are prepared, the superior extension is clipped from the open approach. The flap is then taken to the chest for inset and microanastomosis in the typical manner. The anterior fascial incision can be closed in the preferred manner used in a traditional DIEP. Fascial incisions should range from 1 to 4 cm if the technique is performed appropriately.