Fig.1: retroperitoneal approach in the tissues located between the peritoneum (above) and the psoas muscle (below); the space is relatively narrow and, under a thin fibrous layer, we can spot the ureter and the adipose tissue that covers the angle between the inferior vena cava and the psoas muscle.

Fig.2: the ureter is shown lying on the psoas muscle; the genitofemoral nerve runs on the muscle close to the margin of the adipose tissue.

Fig.3: after moving the ureter forward (toward the top of the image), the inferior vena cava is exposed.

Fig.4: continuing the dissection in the angle between vena cava inf. and psoas muscle, filled by fatty tissue with embedded lymphatic glands and vessels.

Fig.5: in the depth of this space, the sympathetic chain appears, firmly attached to the vertebra.

Fig.6: dissection of the sympathetic chain requires great care in order to avoid injury to the adjacent structures, in particular the vena cava, the lumbar veins and the genitofemoral nerve.

Fig.7: application of a clip with the clip applicator.

Fig.8: lumbar ganglion, located between the inferior vena cava (above) and the psoas muscle, blocked by clips at either end.

Fig.9 (left side): sympathetic nerve partly covered by and embedded into the vertebral attachment of the psoas muscle, requiring dissection of the two structures. It is of utmost importance not to mistake the sympathetic trunk with the genitofemoral nerve, since they often run very close to each other. Coagulation should be avoided by all means.

Fig.10: thin and difficult to detect sympathetic chain embedded in a dense sheath of fibrous tissue, adherent to the longitudinal ligament of the vertebra, and located in a particularly deep slot between vena cava and psoas muscle.

Fig.11: lumbar sympathetic ganglion (with clip) hidden under a lumbar vein and partly covered by the inferior vena cava.

Fig.12 (left side): lumbar artery that slips under the lumbar sympathetic ganglion clamped with two clips at both ends.