5 Intriguing Facts About Your Appendix

Fact 1. The appendix is part of our individuality

We are all different. And so are our appendices. The length of this thin outgrowth from the cecum can range from 5 to 35 cm (1). This organ can boast its existence as early as the 8th week of intrauterine development. The appendix has disappeared many times in the evolutionary process, but even more often has appeared, which gives reason to think of it as more than just some useless remnant. The appendix is present in primates, rabbits, and marsupials; meanwhile, pigs, rats, our cats, and dogs do not enjoy such a luxury (2).

Fact 2. The likelihood of appendicitis largely depends on genetic predisposition

This does not mean that if there were no cases of appendicitis in your family, you won’t have one. But it does mean that if such cases occurred, the probability of developing this trouble increases severalfold (3, 4). This is precisely the case where family history matters.

Fact 3. The appendix is a keeper of our gut microbiome

Our intestines can host all sorts of things depending on our diet, water, and health status. When diarrhea occurs, meant to quickly rid the body of pathogenic microorganisms, there is no time to sort bacteria into good and bad. Therefore, our dear Lactobacilli and Bifidobacteria (as well as other, less well-known but no less important members of our gut microbial community) massively depart from the body during diarrhea, just like the unwelcome guests who caused it. Our wonderful appendix in this situation acts as a sort of microbe stash where pathogens get in very rarely, because it is located away from the active movement of intestinal contents. Also, as expected, there are numerous studies devoted to exploring the microbial etiology of appendicitis (5). And you know what? It may sound surprising, but there are no solid grounds to blame bacteria for the onset of appendicitis — no significant differences in the microbiota composition of normal versus inflamed appendices have been observed. The only exception is fusobacteria. But it is unknown whether these microbes can truly cause trouble or simply swarm to feed when trouble has already begun — a similar situation is seen with colonic neoplasms and ulcerative colitis, where fusobacteria are often highlighted.

The importance of the appendix as a reservoir of biodiversity for our microbiota is also indicated by the fact that patients who had their appendix removed cope worse with relapses of nosocomial infections caused by Clostridium difficile — a fierce bacterium that is one of the causes of diarrhea after antibiotic therapy. Its ferocity is shown by its tendency to establish itself in the gut for a long time, and every fourth person who has dealt with it is again forced to suffer from diarrhea after some time; not to mention that these bacteria are among the most common causes of death from nosocomial infections) (6).

Fact 4. The appendix is an important part of our immunity

The appendix contains a large amount of lymphoid tissue that lines its inner part and is, in particular, an important source of immunoglobulin A — the very ones that stand guard over our mucous membranes and constantly remind our microbes who the host is (7).

There is also a belief that the lymphoid tissue, specifically its thickening and swelling, may be the first note of the overture called "acute appendicitis." This can happen, for example, as a reaction to a viral infection. There are even studies that trace a certain correlation between outbreaks of viral diseases and cases of appendicitis (8).

Fact 5. Good news for those who no longer have an appendix

First of all, appendicitis no longer threatens you! And that’s significant, because acute appendicitis is no pleasant matter and can have deadly consequences — in 2015, for example, it caused 50,000 deaths (9).

There is also comforting evidence from studies showing that removing the appendix may slow the onset of Parkinson’s disease and reduce the likelihood of certain inflammatory processes in the gut (10).

And there is one more reason to celebrate living in the era of accessible general anesthesia and medical knowledge :)