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Difficult to Diagnose

It can be difficult to diagnose appendicitis.  Half of the 700,000 cases of suspected appendicitis in the US each year lack the typical symptoms of fever and pain in the lower right abdomen.

The reasons why diagnosing appendicitis is difficult include:

  • The variable location of the appendix.  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.
  • Symptoms may be atypical. For example, the pain of appendicitis sometimes is located in the right upper abdomen, and the pain of diverticulitis on the right side. Elderly patients and patients taking corticosteroids may have little or no pain and tenderness when there is inflammation, for example, cholecystitis or diverticulitis. This occurs because corticosteroids reduce the inflammation.
  • Tests are not always abnormal. Ultrasounds and CT scans may fail to demonstrate appendicitis or even abscesses, particularly if the abscesses are small. The CBC and other blood tests may be normal despite severe infection or inflammation.
  • Diseases can mimic one another. 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.

  • The characteristics of the pain may change. Examples discussed previously include the extension of the inflammation of pancreatitis to involve the entire abdomen and the progression of biliary colic to cholecystitis.

Patient states may also affect diagnosis:

  • Pregnancy. The incidence of appendicitis is unchanged in pregnancy, but the clinical presentation becomes even more variable. During pregnancy, the appendix migrates in a counterclockwise direction toward the right kidney, rising above the iliac crest at about 4.5 months' gestation. RLQ pain and tenderness dominate in the first trimester, but in the latter half of pregnancy, right upper quadrant (RUQ) or right flank pain must be looked upon as a possible sign of appendiceal inflammation. Nausea, vomiting, and anorexia are common in uncomplicated first trimester pregnancies, but their reappearance later in gestation should be viewed with suspicion.
  • Nonpregnant women of childbearing age. Patients in this group who develop appendicitis are misdiagnosed in 33% of cases. The most frequent misdiagnoses are PID, followed by gastroenteritis and urinary tract infection.
  • Children.  Children with appendicitis are misdiagnosed in 25-30% of cases overall, and the rate of initial misdiagnosis is inversely related to the age of the patient. The most common misdiagnosis is gastroenteritis, followed by upper respiratory infection and lower respiratory infection.
  • Elderly patients.  Appendicitis in patients older than 60 years accounts for 10% of all appendectomies.   The incidence of misdiagnosis is increased in the elderly. In those patients with comorbid conditions, diagnostic delay does correlate with increased morbidity and mortality. Older patients tend to seek medical attention later in the course of illness; therefore, duration of symptoms in excess of 24-48 hours should not dissuade the physician from the diagnosis.