Apr 27 2008
APPENDICITIS
APPENDICITIS
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.
Appendicitis (or epityphlitis) is a condition characterized by inflammation of the appendix. While mild cases may resolve without treatment, most require removal of the inflamed appendix, either by laparotomy or laparoscopy. Untreated, mortality is high, mainly due to peritonitis and shock. Reginald Fitz first described acute appendicitis in 1886, and it has been recognized as one of the most common causes of acute abdomen pain worldwide.
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.
Causes
Obstruction of the appendiceal lumen has been attributed to a number of common sources including from fecaliths (a hard mass of fecal matter), normal stool, viral induced ulcers, or lymphoid hyperplasia. Once this obstruction occurs the appendix subsequently becomes filled with mucus and distends, increasing intraluminal and intramural pressures, resulting in thrombosis and occlusion of the small vessels, and stasis of lymphatic flow. As these progress, the appendix becomes ischemic and then necrotic. Rarely, spontaneous recovery can occur at this point. As bacteria begin to leak out through the dying walls, pus forms within and around the appendix (suppuration). The end result of this cascade is appendiceal rupture causing peritonitis, which may lead to septicemia and eventually death.
A number of environmental factors involving diet and hygiene have been proposed to be alternate causes of appendicitis, none of which has been studied in detail. According to the Medical Journal of Australia, “Dietary theories, notably an inadequate fibre intake, have been advanced to account for the geography of the disease, but it is clear that diet can not fully explain the epidemiology.
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.
Symptoms
Symptoms of acute appendicitis can be classified into two types, typical and atypical (Hobler, K., 1998). The typical history includes pain starting centrally (periumbilical) before localising to the right iliac fossa (the lower right side of the abdomen); this is due to the poor localizing (spatial) property of visceral nerves from the mid-gut, followed by the involvement of somatic nerves (parietal peritoneum) as the inflammation progresses. The pain is usually associated with loss of appetite and fever. Nausea or vomiting may or may not occur. With the typical type, diagnosis is easier to make, surgery occurs earlier and findings are often less severe (Hobler, K., 1998).
Atypical symptoms may include pain beginning in the right lower quadrant, diarrhea and a more prolonged, smoldering course. Being more difficult to diagnose, CT scans and ultrasound tests are more useful. Surgical findings are more apt to be severe (suppuration, abscess, perforation, etc.(Hobler,K., 1998).
In either type of history, physical findings of appendicitis usually include localized findings in the right lower quadrant suggesting peritonitis. The abdominal wall becomes very sensitive to gentle pressure (palpation)and tapping (percussion). Coughing causes point tenderness in this area (McBurney’s Point) and this is the least painful way to localize the inflamed appendix. If the abdomen on palpation is also involuntarily guarded (rigid), there should be a strong suspicion of peritonitis requiring urgent surgical intervention.
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. The exact point is named after Dr. Charles McBurney–McBurney’s point. If the appendix ruptures and infection spreads throughout the abdomen, the pain becomes diffuse again as the entire lining of the abdomen becomes inflamed.
Diagnosis
Diagnosis is based on history and physical examination backed by an elevation of neutrophilic white cells. Atypical histories often requires ultrasound and/or CT scanning (Hobler, K., 1998).
The classical history in appendicitis is diffuse pain in the periumbilical region which then localizes as pain and tenderness at McBurney’s point (associated with an inflamed appendix coming in contact with the surrounding parietal peritoneum). This point is located on the right-hand side of the abdomen one-third of the distance between the anterior superior iliac spine and the navel. Here, on gentle palpation, the abdominal muscles often feel firm to rigid because of involuntary spasm, and a cough also produces a localized soreness.
Other physical findings include right-side tenderness on a digital rectal exam. Since the appendix normally lies on the right, if a finger is inserted into the rectum and there may be tenderness when pressure is applied toward the right indicating an increased likelihood that the patient has a pelvic appendix.
Other signs used in the diagnosis of appendicitis are the psoas sign (useful in retrocecal appendicitis), the obturator sign (specifically the obturator internus muscle), Blumberg’s sign, and Rovsing’s sign.
Ultrasonography and Doppler sonography also provide useful means to detect appendicitis, especially in children. In some cases (15% approximately), however, ultrasonography of the iliac fossa does not reveal any abnormalities despite the presence of appendicitis. This is especially true of early appendicitis before the appendix has become significantly distended and in adults where larger amounts of fat and bowel gas make actually seeing the appendix technically difficult. Despite these limitations, in experienced hands sonographic imaging can often distinguish between appendicitis and other diseases with very similar symptoms such as inflammation of lymph nodes near the appendix or pain originating from other pelvic organs such as the ovaries or fallopian tubes.
In places where it is readily available, CT scan has become the diagnostic test of choice, especially in adults whose diagnosis is not obvious on history and physical. (The use of CT in pregnant women and children is significantly limited, however, by concerns regarding radiation exposure.) A properly performed CT scan with modern equipment has a detection rate (sensitivity) of over 95% and a similar specificity. Signs of appendicitis on CT scan include lack of contrast (oral dye) in the appendix and direct visualization of appendiceal enlargement (greater than 6 mm in diameter on cross section). The inflammation caused by appendicitis in the surrounding peritoneal fat (so called “fat stranding”) can also be observed on CT, providing a mechanism to detect early appendicitis and a clue that appendicitis may be present even when the appendix is not well seen. Thus, diagnosis of appendicitis by CT is made more difficult in very thin patients and in children, both of whom tend to lack significant fat within the abdomen. The utility of CT scanning is made clear, however, by the impact it has had on negative appendectomy rates. For example, use of CT for diagnosis of appendicitis in Boston, MA has decreased the chance of finding a normal appendix at surgery from 20% in the pre-CT era to only 3% according to data from the Massachusetts General Hospital.
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 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.
The surgeon faced with a patient suspected of having appendicitis always must consider and look for other conditions that can mimic appendicitis. Among the conditions that mimic appendicitis are:
- Meckel’s diverticulitis. A Meckel’s diverticulum is a small outpouching of the small intestine which usually is located in the right lower abdomen near the appendix. The diverticulum may become inflamed or even perforate (break open or rupture). If inflamed and/or perforated, it usually is removed surgically.
- Pelvic inflammatory disease. The right fallopian tube and ovary lie near the appendix. Sexually active women may contract infectious diseases that involve the tube and ovary. Usually, antibiotic therapy is sufficient treatment, and surgical removal of the tube and ovary are not necessary.
- Inflammatory diseases of the right upper abdomen. Fluids from the right upper abdomen may drain into the lower abdomen where they stimulate inflammation and mimic appendicitis. Such fluids may come from a perforated duodenal ulcer, gallbladder disease, or inflammatory diseases of the liver, e.g., a liver abscess.
- Right-sided diverticulitis. Although most diverticuli are located on the left side of the colon, they occasionally occur on the right side. When a right-sided diverticulum ruptures it can provoke inflammation they mimics appendicitis.
- Kidney diseases. The right kidney is close enough to the appendix that inflammatory problems in the kidney-for example, an abscess-can mimic appendicitis.
Treatment
Once a diagnosis of appendicitis is made, an appendectomy usually is performed. Antibiotics almost always are begun prior to surgery and as soon as appendicitis is suspected.
There is a small group of patients in whom the inflammation and infection of appendicitis remain mild and localized to a small area. The body is able not only to contain the inflammation and infection but to resolve it as well. These patients usually are not very ill and improve during several days of observation. This type of appendicitis is referred to as “confined appendicitis” and may be treated with antibiotics alone. The appendix may or may not be removed at a later time.
On occasion, a person may not see their doctor until appendicitis with rupture has been present for many days or even weeks. In this situation, an abscess usually has formed, and the appendiceal perforation may have closed over. If the abscess is small, it initially can be treated with antibiotics; however, the abscess usually requires drainage. A drain (a small plastic or rubber tube) usually is inserted through the skin and into the abscess with the aid of an ultrasound or CT scan that can determine the exact location of the abscess. The drain allows pus to flow from the abscess out of the body. The appendix may be removed several weeks or months after the abscess has resolved. This is called an interval appendectomy and is done to prevent a second attack of appendicitis.
The treatment begins by keeping the patient from eating or drinking anything, even water, in preparation for surgery. An intravenous drip is used to hydrate the patient. Antibiotics given intravenously such as cefuroxime and metronidazole may be administered early to help kill bacteria and thus reduce the spread of infection in the abdomen and postoperative complications in the abdomen or wound. Equivocal cases may become more difficult to assess with antibiotic treatment and benefit from serieal examinations. If the stomach is empty (no food in the past six hours) general anaesthesia is usually used. Otherwise, spinal anaesthesia may be used.
The surgical procedure for the removal of the appendix is called an appendicectomy (also known as an appendectomy). Often now the operation can be performed via a laparoscopic approach, or via three small incisions with a camera to visualize the area of interest in the abdomen. If the findings reveal suppurative appendicitis with complications such as rupture, abscess, adhesions, etc., conversion to open laparotomy may be necessary. An open laparotomy incision if required most often centers on the area of maximum tenderess, McBurney’s Point, in the right lower quadrant. A transverse or a gridiron diagonal incision is used most commonly.
According to a meta-analysis from the Cochrane Collaboration comparing laparoscopic and open procedures, laparoscopic procedures seem to have various advantages over the open procedure. Wound infections were less likely after laparoscopic appendicectomy than after open appendicectomy (odds ratio 0.45; CI 0.35 to 0.58), but the incidence of intraabdominal abscesses was increased (odds ratio 2.48; CI 1.45 to 4.21). The duration of surgery was 12 minutes (CI 7 to 16) longer for laparoscopic procedures. Pain on day 1 after surgery was reduced after laparoscopic procedures by 9 mm (CI 5 to 13 mm) on a 100 mm visual analogue scale. Hospital stay was shortened by 1.1 day (CI 0.6 to 1.5). Return to normal activity, work, and sport occurred earlier after laparoscopic procedures than after open procedures. While the operation costs of laparoscopic procedures were significantly higher, the costs outside hospital were reduced. Young female, obese, and employed patients seem to benefit from the laparoscopic procedure more than other groups.
Surgery may last from 15 minutes in typical appendicitis in thin patients to several hours in complicated cases. Hospital lengths of stay usually range from overnight to a matter of days (rarely weeks in complicated cases.) The pain is not always constant, in some cases it can stop for a day and then come back.
Prognosis
Most appendicitis patients recover easily with treatment, but complications can occur if treatment is delayed or if peritonitis occurs.
Recovery time depends on age, condition, complications, and other circumstances, including the amount of alcohol consumption, but usually is between 10 and 28 days. For young children (around 10 years old) the recovery takes three weeks.
The real possibility of life-threatening peritonitis is the reason why acute appendicitis warrants speedy evaluation and treatment. The patient may have to undergo a medical evacuation. Appendectomies have occasionally been performed in emergency conditions (i.e. outside of a proper hospital), when a timely medical evaluation was impossible.
Typical acute appendicitis responds quickly to appendectomy and occasionally will resolve spontaneously. If appendicitis resolves spontaneously, it remains controversial whether an elective interval appendectomy should be performed to prevent a recurrent episode of appendicitis. Atypical appendicitis (associated with suppurative appendicitis) is more difficult to diagnose and is more apt to be complicated even when operated early. In either condition prompt diagnosis and appendectomy yield the best results with full recovery in two to four weeks usually. Mortality and severe complications are unusual but do occur, especially if peritonitis persists and is untreated.
An unusual complication of an appendectomy is “stump appendicitis”: inflammation occurs in the remnant appendiceal stump left after a prior, incomplete appendectomy.
What is new about appendicitis?
Recently it has been hypothesized that some episodes of appendicitis-like symptoms, especially recurrent symptoms, may be due to an increased sensitivity of the intestine and appendix from a prior episode of inflammation. That is, the recurrent symptoms are not due to recurrent episodes of inflammation. Rather, prior inflammation has made the nerves of the intestines and appendix or the central nervous system that innervate them more sensitive to normal stimuli, that is, with stimuli other than inflammation. This will be a difficult, if not impossible, hypothesis to confirm.
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