Autonomic nerve preservation in rectal cancer surgery --the forgotten part of the TME message a practical "workshop" description for surgeons.

Conceptually TME has its basis in embryology. The original hypothesis was that cancer spread will tend, initially at least, to remain within the embryologic lymphovascular hindgut "envelope" the mesorectum and mesocolon. The corollary to the perfect specimen and cure is the perfect preservation of the layers surrounding the mesorectum which, are formed by the autonomic nerves and plexuses. The first obstacle is that few realistic photographs, sketches or diagrams have been published and visualisation and lighting low down in the pelvis is always problematic. Even when they are understood and visualised the difficulties inherent in preserving these nerves are due to the fact that they are actually adherent to the mesorectum at certain points where the dissection becomes particularly challenging. The most important and most adherent areas are the so-called "lateral ligaments"--low down laterally and anterolaterally where the inferior hypogastric plexuses (virtually the pelvic sex-brain) tether the whole mesorectal package. When the specimen has been carefully released it lifts up in a somewhat spectacular fashion--hence the old idea that there are ligaments at these points. A lesser degree of adherence may be found at various other points and particular care is required anteriorly where the nerves are converging towards the bulb of the penis with a trapezoidal septum between them--Denonvillier's "fascia"--which is in turn adherent to the anterior mesorectum and lower down in the prostate.