The appendix as viewed at laparoscopy
The appendix is a worm-like extension arising from the colon
The appendix is a small blind tube connected to the start of the large bowel – the caecum. The full name is “vermiform” (or worm-like) appendix.
The appendix may become blocked, then inflamed, then form into an abscess that could perforate. Removal of the acutely inflamed appendix, hopefully before rupture, is a common operation.
The appendix has been assumed to be a vestigial or unnecessary structure. Comparison of humans with herbivorous animals would support the idea that the appendix was previously a larger structure important for digestion of cellulose.
However recent research would suggest that the appendix plays an important part in the immune system of the gut at least in the early years. There seems to be a sampling of intestinal bacteria and a “training” of the immune system to react appropriately to intestinal bacteria.
An interesting observation is that having appendicitis appears to protect from getting ulcerative colitis. The idea of having an elective or planned appendectomy for control of ulcerative colitis is still debated.
Appendicitis is inflammation of the appendix. This is caused by obstruction of the entry to the appendix and bacterial infection then abscess formation. This is usually an acute illness over 2-3 days and the diagnosis is reasonably straightforward. Occasionally there can be aborted episodes. The diagnosis of a "grumbling appendix" as a cause of recurrent pain in the right lower abdomen is much less certain. Often the diagnosis is irritable bowel or constipation. An "appendicitis-like" illness can be the starting point for Crohn's disease of the terminal ileum.
A viral infection of the lymph nodes in this region called mesenteric adenitis is thought to be the cause of an appendicitis- like illness but a normal appendix at operation.