What is the appendix?

The appendix is a closed-ended, narrow tube up to several inches in length that attaches to the cecum (the first part of the colon) like a worm. (The anatomical name for the appendix, vermiform appendix, means worm-like appendage.) The inner lining of the appendix produces a small amount of mucus that flows through the open center of the appendix and into the cecum. The wall of the appendix contains lymphatic tissue that is part of the immune system for making antibodies. Like the rest of the colon, the wall of the appendix also contains a layer of muscle, but the muscle is poorly developed.

What is appendicitis and what causes appendicitis?

Appendicitis means inflammation of the appendix. It is thought that appendicitis begins when the opening from the appendix into the cecum becomes blocked. The blockage may be due to a build-up of thick mucus within the appendix or to stool that enters the appendix from the cecum. The mucus or stool hardens, becomes rock-like, and blocks the opening. This rock is called a fecalith (literally, a rock of stool). At other times, the lymphatic tissue in the appendix may swell and block the appendix. After the blockage occurs, bacteria which normally are found within the appendix begin to invade (infect) the wall of the appendix. The body responds to the invasion by mounting an attack on the bacteria, an attack called inflammation. An alternative theory for the cause of appendicitis is an initial rupture of the appendix followed by spread of bacteria outside the appendix.. The cause of such a rupture is unclear, but it may relate to changes that occur in the lymphatic tissue, for example, inflammation, that line the wall of the appendix.)

If the inflammation and infection spread through the wall of the appendix, the appendix can rupture. After rupture, infection can spread throughout the abdomen; however, it usually is confined to a small area surrounding the appendix (forming a peri-appendiceal abscess).

Sometimes, the body is successful in containing ("healing") the appendicitis without surgical treatment if the infection and accompanying inflammation do not spread throughout the abdomen. The inflammation, pain and symptoms may disappear. This is particularly true in elderly patients and when antibiotics are used. The patients then may come to the doctor long after the episode of appendicitis with a lump or a mass in the right lower abdomen that is due to the scarring that occurs during healing. This lump might raise the suspicion of cancer.

What are the complications of appendicitis?

The most frequent complication of appendicitis is perforation. Perforation of the appendix can lead to a periappendiceal abscess (a collection of infected pus) or diffuse peritonitis (infection of the entire lining of the abdomen and the pelvis). The major reason for appendiceal perforation is delay in diagnosis and treatment. In general, the longer the delay between diagnosis and surgery, the more likely is perforation. The risk of perforation 36 hours after the onset of symptoms is at least 15%. Therefore, once appendicitis is diagnosed, surgery should be done without unnecessary delay.

A less common complication of appendicitis is blockage of the intestine. Blockage occurs when the inflammation surrounding the appendix causes the intestinal muscle to stop working, and this prevents the intestinal contents from passing. If the intestine above the blockage begins to fill with liquid and gas, the abdomen distends and nausea and vomiting may occur. It then may be necessary to drain the contents of the intestine through a tube passed through the nose and esophagus and into the stomach and intestine.

A feared complication of appendicitis is sepsis, a condition in which infecting bacteria enter the blood and travel to other parts of the body. This is a very serious, even life-threatening complication. Fortunately, it occurs infrequently.

What are the symptoms of appendicitis?

The main symptom of appendicitis is abdominal pain. The pain is at first diffuse and poorly localized, that is, not confined to one spot. (Poorly localized pain is typical whenever a problem is confined to the small intestine or colon, including the appendix.) The pain is so difficult to pinpoint that when asked to point to the area of the pain, most people indicate the location of the pain with a circular motion of their hand around the central part of their abdomen. A second, common, early symptom of appendicitis is loss of appetite which may progress to nausea and even vomiting. Nausea and vomiting also may occur later due to intestinal obstruction.

As appendiceal inflammation increases, it extends through the appendix to its outer covering and then to the lining of the abdomen, a thin membrane called the peritoneum. Once the peritoneum becomes inflamed, the pain changes and then can be localized clearly to one small area. Generally, this area is between the front of the right hip bone and the belly button. If the appendix ruptures and infection spreads throughout the abdomen, the pain becomes diffuse again as the entire lining of the abdomen becomes inflamed.

How is appendicitis diagnosed?

The diagnosis of appendicitis begins with a thorough history and physical examination. Patients often have an elevated temperature, and there usually will be moderate to severe tenderness in the right lower abdomen when the doctor pushes there. If inflammation has spread to the peritoneum, there is frequently rebound tenderness. Rebound tenderness is pain that is worse when the doctor quickly releases his hand after gently pressing on the abdomen over the area of tenderness.


White Blood Cell Count

The white blood cell count in the blood usually becomes elevated with infection. In early appendicitis, before infection sets in, it can be normal, but most often there is at least a mild elevation even early. Unfortunately, appendicitis is not the only condition that causes elevated white blood cell counts. Almost any infection or inflammation can cause this count to be abnormally high. Therefore, an elevated white blood cell count alone cannot be used as a sign of appendicitis.

Urinalysis

Urinalysis is a microscopic examination of the urine that detects red blood cells, white blood cells and bacteria in the urine. Urinalysis usually is abnormal when there is inflammation or stones in the kidneys or bladder. The urinalysis also may be abnormal with appendicitis because the appendix lies near the ureter and bladder. If the inflammation of appendicitis is great enough, it can spread to the ureter and bladder leading to an abnormal urinalysis. Most patients with appendicitis, however, have a normal urinalysis. Therefore, a normal urinalysis suggests appendicitis more than a urinary tract problem.

Abdominal X-Ray

An abdominal x-ray may detect the fecalith (the hardened and calcified, pea-sized piece of stool that blocks the appendiceal opening) that may be the cause of appendicitis. This is especially true in children.

Ultrasound

An ultrasound is a painless procedure that uses sound waves to identify organs within the body. Ultrasound can identify an enlarged appendix or an abscess. Nevertheless, during appendicitis, the appendix can be seen in only 50% of patients. Therefore, not seeing the appendix during an ultrasound does not exclude appendicitis. Ultrasound also is helpful in women because it can exclude the presence of conditions involving the ovaries, fallopian tubes and uterus that can mimic appendicitis.

Barium Enema

A barium enema is an x-ray test where liquid barium is inserted into the colon from the anus to fill the colon. This test can, at times, show an impression on the colon in the area of the appendix where the inflammation from the adjacent inflammation impinges on the colon. Barium enema also can exclude other intestinal problems that mimic appendicitis, for example Crohn's disease.


Computerized tomography (CT) Scan

In patients who are not pregnant, a CT scan of the area of the appendix is useful in diagnosing appendicitis and peri-appendiceal abscesses as well as in excluding other diseases inside the abdomen and pelvis that can mimic appendicitis.


Laparoscopy

Laparoscopy is a surgical procedure in which a small fiberoptic tube with a camera is inserted into the abdomen through a small puncture made on the abdominal wall. Laparoscopy allows a direct view of the appendix as well as other abdominal and pelvic organs. If appendicitis is found, the inflamed appendix can be removed with the laparascope. The disadvantage of laparoscopy compared to ultrasound and CT is that it requires a general anesthetic.

There is no one test that will diagnose appendicitis with certainty. Therefore, the approach to suspected appendicitis may include a period of observation, tests as previously discussed, or surgery.

Why can it be difficult to diagnose appendicitis?

It can be difficult to diagnose appendicitis. The position of the appendix in the abdomen may vary. Most of the time the appendix is in the right lower abdomen, but the appendix, like other parts of the intestine, has a mesentery. This mesentery is a sheet-like membrane that attaches the appendix to other structures within the abdomen. If the mesentery is large, it allows the appendix to move around. In addition, the appendix may be longer than normal. The combination of a large mesentery and a long appendix allows the appendix to dip down into the pelvis (among the pelvic organs in women). It also may allow the appendix to move behind the colon (called a retro-colic appendix). In either case, inflammation of the appendix may act more like the inflammation of other organs, for example, a woman's pelvic organs.

The diagnosis of appendicitis also can be difficult because other inflammatory problems may mimic appendicitis. Therefore, it is common to observe patients with suspected appendicitis for a period of time to see if the problem will resolve on its own or develop characteristics that more strongly suggest appendicitis or, perhaps, another condition.