English subtitles for clip: File:Appendicitis.webm

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The appendix is the little one-ended tube that’s attached to the cecum of the large

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intestine, sometimes it’s called the vermiform appendix, where vermiform means “worm-shaped”,

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so, that should paint a pretty clear picture of what it looks like.

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This odd, yet kinda cute little worm-like structure’s function is actually unknown,

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though some theories suggest it might be a “safe-house” for the gut flora, and some

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evidence seems to suggests it plays a part in the lymphatic and immune system; other,

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arguably more cynical viewpoints maintain that it’s just a useless vestigial organ

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from our ancestors.

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Whatever the case, the fact remains, it’s pretty talented at getting inflamed and causing

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abdominal pain, a condition known as appendicitis, as much as 10% of the population develops

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appendicitis, and it’s the most common surgical emergency of the abdomen.

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Since the appendix is a hollow tube, the most common cause of inflammation is something

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getting stuck in or obstructing that tube, like a fecalith, a hardened lump of fecal

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matter that finds it’s way into the the lumen of the appendix and wedges itself there.

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It could also be other things though, like seeds that weren’t digested, or even pinworm

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infections, which are intestinal parasites.

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Another cause of obstruction, especially in children and adolescents, is lymphoid follicle

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growth, also known as lymphoid hyperplasia.

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Lymphoid follicles are dense collections of lymphocytes that get to their maximum size

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in the appendix during adolescence.

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Sometimes this growth can literally obstruct the tube.

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Also, when exposed to viral infections like adenovirus, measles, or even after immunizations,

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the immune system ramps up and these follicles can grow as well.

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Whatever the obstruction is, now this appendix is plugged up, right?

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Well, the intestinal lumen, including the appendix, is always secreting mucus and fluids

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from its mucosa to keep pathogens from entering the bloodstream and also to keep the tissue

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moist.

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Even when it’s plugged, the appendix keeps secreting as usual.

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When this happens, fluid and mucus builds up, which increases the pressure in the appendix,

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and just like when you fill up a water balloon, it gets bigger and physically pushes ons the

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afferent visceral nerve fibers nearby, causing abdominal pain.

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Along with that, the flora and bacteria in the gut are now trapped, and intestinal bacteria

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that are usually kept in check in the gut, like E. coli and Bacteroides fragilis are

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now free to multiply.

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This causes the immune system to recruit white blood cells and pus starts to accumulate in

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the appendix.

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This activation of the immune system can be seen in the lab as an increase in the serum

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white blood cell count.

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Patients might also develop a fever in response to the infection, which in combination with

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right lower quadrant abdominal pain at the point roughly where the appendix is, known

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as known as mcburney’s point, is a super important sign for identifying appendicitis.

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Also, along with fever, other classic symptoms include nausea and vomiting.

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Now if obstruction persists, the pressure in the appendix increases even more.

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At a certain point, as the pressure keeps growing and it continues to swell up, it pushes

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on and compresses the small blood vessels that supply the appendix with blood and oxygen.

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Without oxygen, the cells in the walls of the appendix become ischemic and eventually

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die.

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Since these cells were responsible for secreting mucus and keeping bacteria out, now the growing

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colony of bacteria can invade the wall of the appendix.

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As more cells die, the appendiceal walls become weaker and weaker and for a small proportion

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of patients, to the point where the appendix ruptures.

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Rupture of an infected appendix allows the bacteria to escape the appendix and get into

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the peritoneum, and patients often experience peritonitis with rebound tenderness, meaning

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pain when pressure is taken off, again around mcburney’s point.

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Patients might also have some abdominal guarding, where their abdominal muscles tense up when

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pressed to try and avoid pain.

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The most common complication with a ruptured appendix is pus and fluid gets out and forms

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an abcess around the appendix, called a periappendiceal abscess.

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Sometimes subphrenic abscesses might also form, these would be tiny abscesses below

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the diaphragm but above the liver or spleen.

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The standard treatment for appendicitis is appendectomy, which is surgical removal of

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the appendix along with antibiotics.

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If patients have abscesses these are also important to surgically drain.

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Removing the appendix isn’t known to have any negative side effects, and sometimes it’s

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removed if the surgeons are already doing an abdominal surgery for some other reason

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just to avoid an appendicitis down the road!