EUS-Assisted Evaluation of Rectal Varices before Banding
Figure 1
(a) The superior rectal vein (SRV) divides into two branches, which enter the lateral wall of rectum, about 10 cm above the dentate line. The middle and inferior rectal veins (MRV & IRV), empty into the caval system. The rectal veins form two plexuses, an internal one lying in the submucosa and the corresponding anal “Subcutaneous” tissue and an external one lying outside the muscular wall of the bowel below the level of the peritoneal reflection. The intrinsic rectal venous plexus consists of two groups of veins draining in opposite direction. The inferior group passes down to form the inferior rectal veins, and dilation of this group leads to formation of external hemorrhoids. The vessels of the superior group in the anal columns lead to the formation of internal hemorrhoids and in the rectum lead to the formation of rectal varices. (b) Four distinct zones of mucosal circulation are seen in rectum with similarity to esophageal circulation. The inflow area is analogous to the gastric zone, the downflow area is analogous to the palisade zone, the outflow area in rectum is analogous to the perforating zone, and the outflow area in anal canal is analogous to the truncal zone of esophageal varices.
