With the patient in the supine position a subcutaneous pocket is formed on the breast wall to hold the flap transplant. After incision of the pectoral muscles above the mediosternal section of the third rib, the cartilage is carefully removed with the Lüer and the underlying arteries and veins dissected for microvascular connection also with the aid of the loupe magnification glasses. The height of the third rib is decisive in this, as dissection at a lower level often fails to find any suitable venous connections.
The blood supply to the skin and the subcutaneous fatty tissue via the musculus glutaeus maximus is ensured by 20-25 perforator vessels. These originate mainly in the arteria glutealis superior and the arteria glutealis inferior. 

Marking the flap dimension is carried out with the patient lying on her side. For the reconstruction of the breast the ipsilateral half of the buttocks is selected. The dissection shape on the buttocks is positioned so that the resulting scar can be concealed well by underwear and swimwear. After determining the dimension of the flap, the superior gluteal artery and the qualitatively best perforator vessel are identified using a Doppler sonograph. 
Flap dissection is carried out with the patient lying on her side. Once the laterocranial border of the musculus glutaeus maximus has been identified the fascia is indicated and further dissection is undertaken below the fascia in the direction of the muscle fibre until a qualitatively good perforator vessel is identified. By spreading the gluteal muscles the perforator vessel is followed deeper to the superior gluteal arteries. 

With the patient in the supine position the microvascular anastomisation is carried out. After releasing the blood flow the flap transplant is inserted into the subcutaneous pocket and shaped on the sitting patient, to match the healthy side as far as possible. 
The S-GAP flap represents a reliable alternative for breast reconstruction with autologous tissue if hypogastric tissue is not available. The amount of fatty tissue over the superior gluteal region corresponds very well with the required breast size. With appropriate flap design the scar can be concealed well by underwear and swimwear. The contour deficit is not as serious as for myocutaneous gluteal flaps. However, in the event that an unpleasing contour deficit ensues, the contralateral side may be suitably shaped in a secondary procedure. Seroma at the donor site can be largely avoided if a compression corset is prescribed for at least 6 weeks after the drains have been removed.  

The introduction of microsurgical techniques has lead to a significant growth in surgical options both for primary as well as for secondary reconstruction. By working with 2 teams simultaneously the operation times can be significantly reduced both for primary as well as for secondary reconstruction. For an experienced team a conventional DIEP reconstruction should not take any longer than 4 hours and a normal S-GAP reconstruction should not last longer than 5 hours. With appropriate surgical techniques the blood loss both for primary as well as for secondary reconstruction can be kept so low that transfusion is usually not required and the previously common own patient donation of blood can be dispensed with. Nevertheless, these reconstructive procedures are not suitable for “microsurgery lone wolves”.  The surgical technique is demanding and requires a high level of peri-operative as well as postoperative logistics. For a surgical team that carries out these procedures frequently it is possible to keep the flap loss rate reasonably low. In our own surgical procedures the flap loss rate for perforator flap plasty has been 2 % for many years.
The advantages and disadvantages of autologous tissue reconstruction are summarised again in Table 2.