With a scalpel blade no. 15, the periumbilical incision is made, and using dissection scissors, the umbilical stalk is isolated down to deep fascia (Fig. 9.3).

The caudal margin of the flap skin island is then incised to the subdermal layer, cautiously looking for vessels running in caudal-cranial direction in the subcutaneous layer (Fig. 9.4a): the SIEV and in some cases the SIEA can be located and dissected free in a caudal direction for several centimetres and then clipped (Fig. 9.4b, c). The SIEV could be of use at the end of the surgery to provide a venous supercharge in case of venous congestion. In the uncommon case in which a SIEA of acceptable size is found, the surgical plan can be radically changed, and instead of a DIEP flap, a SIEA flap can be used.

The dissection is deepened down to the deep abdominal fascia of the rectus muscles (Fig. 9.5).

The skin incision is prolonged (Fig. 9.6), and the flap is raised starting from the lateral tip of the skin island of the side where the “best” (from the preop evaluation) perforators are located (Figs. 9.7 and 9.8a–b).

Dissection is carried out in lateral to medial direction using an electrocautery (set on 50 most frequently) to reduce bleeding on the deep fascia plane. The skin and subcutaneous fat are included in the flap; the anterior abdominal fascia and the rectus abdominis muscle are left untouched (Figs. 9.9 and 9.10).

When the lateral margin of the rectus abdominis is reached, the electrocautery is set to 25 both for cut and coagulation.

All the perforators identified from this moment are preserved. The ones of inadequate calibre can be coagulated (Fig. 9.11a–c). The perforator selected from the preoperative investigations as the preferred one should be reached and judged clinically. The final decision on its adequacy requires the visualization of the subfascial calibre.

Once the main perforator is attained (Fig. 9.12a), the fascia is subsequently incised with a scalpel (Fig. 9.12b, c), the muscle exposed and the vessel visualized (Fig. 9.13).

The blunt dissection proceeds with different instruments according to the surgeon’s preference.

Our favourite technique uses the bipolar, set on very low settings, to coagulate and at the same time gently spread the muscle fibres along the perforator’s course, as no muscle has to be included (Fig. 9.14a). Haemoclips should be used when side branches are encountered. In the unusual case when one perforator is considered to be insufficient to nourish the entire flap, two or three perforators on the same vertical line may be dissected to the point where they join together before entering the deep inferior epigastric artery (DIEA). Although the rules of perforator flap harvesting dictate that no muscle nor fascia should be damaged, there are rare cases when the connection between the muscle fibres, fascia and the perforator is tight. Some surgeons may then consider acceptable to include a small cuff of fascia around the vessel to prevent perforator injuries and spasm during dissection.

Special care must be spent to preserve the motor nerve branches to the rectus muscle to avoid denervation and donor site morbidity.

Dissection is continued in the muscle (Figs. 9.15 and 9.16), and lateral branches are clipped (Fig. 9.17a, b) until the DIEA and the two DIEV comitantes are located under the rectus muscle (Fig. 9.18), which is elevated with the help of a retractor in order to better visualize the main vessels (Figs. 9.19 and 9.20). They are followed toward their origin until the calibre and the pedicle length are considered adequate for anastomosis. In most of the cases, we prefer to reach the confluence of the two comitantes veins in one vessel to optimize the venous drainage of the flap (Figs. 9.21 and 9.22).

Cranially to the perforator, the DIEA and DIEV are clipped.

The contralateral abdominal flap is then raised with the same technique used previously, over the deep fascia (Figs. 9.23 and 9.24a, b).

The best perforators are preserved and temporarily clamped to check that the pedicle already isolated on the contralateral side provides sufficient arterial input and venous drainage (Fig. 9.25).

After 10 min, the colour of the skin island is checked. The border of the perfused area is marked, and the poorly perfused portion is removed.

The clamped perforators are permanently ligated or clipped (Fig. 9.26).

The origin of the isolated DIEA-DIEV pedicle is then sectioned, and the flap is free to be re-anastomosed to the recipient vessels.