The appendix has the function of peristalsis and absorption of water and electrolytes. Peristalsis of the appendix can expel feces and food debris that enter its lumen, and the appendix also has certain immune functions. Appendicitis is an inflammatory change due to a variety of factors and is a common surgical condition, most common in young people and more common in men than women. Acute appendicitis is more common clinically and can develop in women of all ages and during pregnancy. Chronic appendicitis is less common.
Etiology.
Acute appendicitis
Obstruction: The appendix is a long, thin tube, only one end of which is connected to the cecum. Once obstructed, secretions can accumulate in the lumen and increase the internal pressure, compressing the appendiceal wall and impeding distal blood flow. On this basis, the bacteria in the lumen invade the damaged mucosa and cause infection easily. Obstruction is a common underlying factor in the development of acute appendicitis.
Infection: The main factor is direct infection due to bacteria in the appendiceal lumen. The appendiceal cavity is connected to the cecum and therefore has the same species and number of bacteria, mainly E. coli and anaerobic bacteria, as in the cecum. If the appendiceal mucosa is slightly damaged, bacteria invade the canal wall and cause different degrees of infection.
Other: other factors considered to be related to the pathogenesis are visceral nerve reflexes caused by gastrointestinal dysfunction such as diarrhea and constipation, leading to spasm of the appendiceal muscles and blood vessels, which, once exceeding the normal intensity, can produce narrowing of the appendiceal lumen, impaired blood supply, mucosal damage, and bacterial invasion leading to acute inflammation. In addition, the onset of acute appendicitis is associated with dietary habits, constipation and genetic factors.
Chronic appendicitis
Clinically, it can be broadly divided into two categories: recurrent appendicitis and chronic appendicitis. The former is mostly due to the failure to completely remove residual infection from the lesion during an acute appendicitis attack, and the condition is prolonged. Most of them have a clear history of acute appendicitis, and thereafter recurrent appendicitis, but the clinical manifestations are lighter than those of acute appendicitis, and the diagnosis is easy due to a clear medical history. In the latter case, there is no history of acute appendicitis attack, the symptoms are obscure and the signs are mostly inaccurate, and sometimes there is another point of pressure pain, which may be related to another chronic obstruction.
Pathogenesis.
Acute appendicitis
Abdominal pain/typical acute appendicitis initially has pain in the mid-upper abdomen or around the umbilicus, which shifts and fixes in the right lower abdomen after a few hours. The early stage is a visceral nerve reflex pain, so the pain in the mid-upper abdomen and around the umbilicus is more diffuse and often cannot be localized exactly. When the inflammation spreads to the plasma membrane layer and the wall peritoneum, the pain becomes fixed in the right lower abdomen, and the original mid-upper abdominal or periumbilical pain is reduced or disappears. Therefore, the absence of a typical history of metastatic right lower abdominal pain does not exclude acute appendicitis.
Simple appendicitis often presents with paroxysmal or persistent distension and dull pain, and persistent severe pain is often indicative of septic or gangrenous appendicitis. Persistent severe pain extending to the mid-lower abdomen or both lower abdomens is often a sign of gangrenous perforation of the appendix. Sometimes the pain is relieved by perforated appendiceal gangrene, but this pain relief is temporary and other accompanying signs and symptoms do not improve or even increase.
Gastrointestinal symptoms: The gastrointestinal symptoms of simple appendicitis are not prominent. In the early stages there may be nausea and vomiting due to reflex gastric cramps. In pelvic appendicitis or perforated gangrenous appendix, there may be increased frequency of defecation.
Fever: Usually only a low fever without chills, and in septic appendicitis usually not more than 38°C. High fever is usually seen in cases of gangrenous appendix, perforated appendix, or peritonitis. The presence of chills and jaundice suggests a possible complication of suppurative portal phlebitis.
Induration and rebound pain: Abdominal induration is a sign of inflammatory irritation of the mural peritoneum. The appendiceal pressure point is usually located at the McDonald’s point, which is the middle and outer 1/3 intersection of the right anterior superior iliac spine and umbilicus. The pressure point may vary with the anatomic location of the appendix, but the key is a fixed pressure point in the right lower abdomen. The rebound pain is also known as Blumberg’s sign. In patients with obesity or posterior appendicitis, the pressure pain may be mild, but there is significant rebound pain.
Tension of the abdominal muscles: This sign is present when the appendix is suppurating and is particularly prominent in gangrenous perforation with peritonitis. However, in elderly or obese patients with weak abdominal muscles, the presence or absence of abdominal muscle tension can only be determined by a simultaneous examination of the contralateral abdominal muscles for comparison.
Skin sensory hypersensitivity: In the early stages, especially when there is obstruction of the appendiceal cavity, skin sensory hypersensitivity in the right lower abdomen can occur, which corresponds to the 10th to 12th thoracic segmental innervation zone, located in the triangle formed by the highest point of the right iliac crest, the right pubic crest and the umbilicus, also known as Sherren’s triangle, which does not change depending on the location of the appendix, and if the appendix is perforated by gangrene, the skin sensory hypersensitivity in this triangle will If the appendix is perforated, the skin sensory sensitization in this triangle disappears.
Chronic appendicitis
Abdominal pain/pain in the right lower abdomen is characterized by intermittent vague or distending pain, sometimes severe and sometimes mild, in a relatively fixed location. Most patients experience abdominal pain after a full meal, exercise, exertion, cold and prolonged standing. There may be episodes of acute appendicitis during the course of the disease.
Gastrointestinal reactions: Patients often have mild to severe indigestion and loss of appetite. Longer duration of illness may result in weight loss and wasting. There is usually no nausea or vomiting and no abdominal distention, but older patients may have constipation.
Abdominal pressure pain: Pressure pain is the only sign, mainly located in the right lower abdomen, usually small in extent and constant in position, and can only appear when heavy pressure is applied. There is no muscle tension or rebound pain, and there is usually no abdominal mass, but sometimes a distended appendix can be palpated.
Indirect signs: Various specific pressure points such as McKay’s point, Lang’s point and lumbar major muscle sign and Roche’s sign are not always present in the diagnosis of chronic appendicitis.
Other ancillary tests.
Blood count
An increased white blood cell count in patients with acute appendicitis, which accounts for about 90% of patients, is an important basis for clinical diagnosis. As inflammation increases, the leukocyte count increases and may even exceed 20 x 109/L. However, the leukocyte count does not necessarily increase in older, frail patients or those with suppressed immune function. The increase in neutrophil count is accompanied by an increase in leukocyte count. The two are often seen together, but there are cases where only neutrophils are significantly increased, which is equally important.
Urine routine
There is nothing special about urinalysis in patients with acute appendicitis, but routine urinalysis is still necessary to rule out urologic diseases that resemble appendicitis symptoms, such as ureteral calculi. Occasionally, in cases of inflammation of the distal appendix with adhesions to the ureter or bladder, small amounts of red and white blood cells may be present in the urine.
Ultrasonography
May show post-appendicitis because the spastic cecum acts as a transilluminating window to the appendix. It can also play an important role in differential diagnosis because it can show ureteral stones, ovarian cysts, ectopic pregnancy, and enlarged mesenteric lymph nodes, making it particularly useful in the diagnosis and differential diagnosis of acute appendicitis in women. It is used to rule out chronic cholecystitis, chronic mesenteric lymphadenitis, chronic adnexitis in women and chronic urinary tract infections and urinary stones, which are most likely to be confused with chronic appendicitis.
Laparoscopy
This test is one of the most definitive methods for the diagnosis of acute appendicitis. Because the laparoscopy can be inserted through the lower abdomen to directly observe the presence of inflammation of the appendix and to distinguish other adjacent diseases with similar symptoms to appendicitis, it is not only decisive in determining the diagnosis, but also allows for simultaneous treatment.
Barium enema X-ray
Barium enema examination not only clarifies whether the pressure point is located at the appendix, but is also important to exclude other diseases that can be confused with chronic appendicitis, such as ulcer disease, chronic colitis, cecum tuberculosis or cancer, and visceral prolapse. This test is important in patients without a typical history of attacks.
Acute appendicitis
Non-surgical treatment: Anti-infective treatment with antibiotics is available. Once the inflammation is absorbed and subsides, the appendix can return to normal. When the diagnosis of acute appendicitis is clear and surgery is indicated, but the patient’s circumstance or objective conditions do not allow it, non-operative treatment can be used first to delay surgery. If acute appendicitis has combined with limited peritonitis and formed inflammatory masses, non-operative treatment should also be used to make the inflammatory masses absorb before considering elective appendectomy. Patients should be bed rested, fasted, and given intravenous input of water, electrolytes and calories, etc.
Surgical treatment: In principle, acute appendicitis, except for the mucosal edema type which can be cured after conservative treatment, should be treated by appendectomy.
Chronic appendicitis
Surgical treatment is the only effective method, but special care should be taken when deciding to perform appendectomy. After the diagnosis of chronic appendicitis is confirmed, treatment should be surgical in principle, especially in patients with a history of acute attacks. Patients with doubtful diagnosis or elderly patients with serious comorbidities should be temporarily treated non-operatively and followed up in the outpatient clinic.