New insights in the neuroanatomy of the human adult superior hypogastric plexus and hypogastric nerves.

The superior hypogastric plexus (SHP) is an autonomic plexus, located ventrally to the abdominal aorta and its bifurcation, innervating pelvic viscera. It is classically described as being composed of merely sympathetic fibres. However, post-operative complications after surgery damaging the peri-aortic retroperitoneal compartment suggest the existence of parasympathetic fibres. This immunohistochemical study describes the neuroanatomical composition of the human mature SHP.,Eight pre-determined retroperitoneal localizations including the lumbar splanchnic nerves, the SHP and the HN were studied in four human cadavers. Control tissues (white rami, grey rami, vagus nerve, splanchnic nerves, sympathetic ganglia, sympathetic chain and spinal nerve) were collected to verify the results. All tissues were stained with haematoxylin and eosin and antibodies S100, tyrosine hydroxylase (TH), vasoactive intestinal peptide (VIP) and myelin basic protein (MBP) to identify pre- and postganglionic parasympathetic and sympathetic nerve fibres.,All tissues comprising the SHP and hypogastric nerves (HN) showed isolated expression of TH, VIP and MBP, revealing the presence of three types of fibres: postganglionic adrenergic sympathetic fibres marked by TH, unmyelinated VIP-positive fibres and myelinated preganglionic fibres marked by MBP. Analysis of control tissues confirmed that TH, VIP and MBP were well usable to interpret the neurochemical composition of the SHP and HN.,The human SHP and HN contain sympathetic and most likely postganglionic parasympathetic fibres. The origin of these fibres is still to be elucidated, however surgical damage in the peri-aortic retroperitoneal compartment may cause pelvic organ dysfunction related to both parasympathetic and sympathetic denervation.