Appendicitis is a common and urgent surgical illness with protean manifestations, generous overlap with other clinical syndromes, and significant morbidity, which increases with diagnostic delay. No single sign, symptom, or diagnostic test accurately confirms the diagnosis of appendiceal inflammation in all cases.

The surgeon’s goals are to evaluate a relatively small population of patients referred for suspected appendicitis and to minimize the negative appendectomy rate without increasing the incidence of perforation.

The emergency physician must evaluate the larger group of patients who present to the ED with abdominal pain of all etiologies with the goal of approaching 100% sensitivity for the diagnosis in a time-, cost-, and consultation-efficient manner.


Obstruction of the appendiceal lumen is the primary cause of appendicitis. Obstruction of the lumen leads to distension of the appendix due to accumulated intraluminal fluid. Ineffective lymphatic and venous drainage allows bacterial invasion of the appendiceal wall and, in advanced cases, perforation and spillage of pus into the peritoneal cavity.

CLINICAL (History)

Variations in the position of the appendix, age of the patient, and degree of inflammation make the clinical presentation of appendicitis notoriously inconsistent.

In addition, patients with many other disorders present with symptoms similar to those of appendicitis. Examples include the following:

–        Pelvic inflammatory disease (PID) or tubo-ovarian abscess

–        Endometriosis

–        Ovarian cyst or torsion

–        Ureterolithiasis and renal colic

–        Degenerating uterine leiomyomata

–        Diverticulitis

–        Crohn disease

–        Colonic carcinoma

–        Rectus sheath hematoma

–        Cholecystitis

–        Bacterial enteritis

–        Mesenteric adenitis

–        Omental torsion

  • The classic history of anorexia and periumbilical pain followed by nausea, right lower quadrant (RLQ) pain, and vomiting occurs in only 50% of cases.
  • Migration of pain from the periumbilical area to the RLQ is the most discriminating feature of the patient’s history. This finding has a sensitivity and specificity of approximately 80%.
  • When vomiting occurs, it nearly always follows the onset of pain. Vomiting that precedes pain is suggestive of intestinal obstruction, and the diagnosis of appendicitis should be reconsidered.
  • Nausea is present in 61-92% of patients; anorexia is present in 74-78% of patients. Neither finding is statistically different from findings in ED patients with other etiologies of abdominal pain.
  • Diarrhea or constipation is noted in as many as 18% of patients and should not be used to discard the possibility of appendicitis.
  • Duration of symptoms is less than 48 hours in approximately 80% of adults but tends to be longer in elderly persons and in those with perforation. Approximately 2% of patients report duration of pain in excess of 2 weeks.
  • A history of similar pain is reported in as many as 23% of cases. A history of similar pain, in and of itself, should not be used to rule out the possibility of appendicitis.
  • An inflamed appendix near the urinary bladder or ureter can cause irritative voiding symptoms and hematuria or pyuria. Cystitis in male patients is rare in the absence of instrumentation. Consider the possibility of an inflamed pelvic appendix in male patients with apparent cystitis.
  • The literature is inconsistent as to whether rectal examination is helpful in making the diagnosis; however, failure to perform a rectal examination is frequently cited in successful malpractice claims.


  • Obstruction of the appendiceal lumen usually precipitates appendicitis.
  • The most common causes of luminal obstruction are fecaliths and lymphoid follicle hyperplasia.

–        Fecaliths form when calcium salts and fecal debris become layered around a nidus of inspissated fecal material located within the appendix.

–        Lymphoid hyperplasia is associated with a variety of inflammatory and infectious disorders including Crohn disease, gastroenteritis, amebiasis, respiratory infections, measles, and mononucleosis.

–        Obstruction of the appendiceal lumen has less commonly been associated with parasites (eg, Schistosomes species, Strongyloides species), foreign material (eg, shotgun pellet, intrauterine device, tongue stud, activated charcoal), tuberculosis, and tumors.

Lab Studies

  • Complete blood cell count
  • C-reactive protein test
  • Urinalysis

Complete blood cell count

–        Studies consistently show that 80-85% of adults with appendicitis have a WBC count greater than 10,000 cells/mm3. Neutrophilia greater than 75% occurs in 78% of patients. Fewer than 4% of patients with appendicitis have a WBC count less than 10,000 cells/mm3 and neutrophilia less than 75%.

–        CBC tests are inexpensive, rapid, and widely available; however, the findings are nonspecific, and 4% of cases are missed.

–        The literature is inconsistent with regard to WBC counts in children and elderly patients with appendicitis

C-reactive protein test

–        C-reactive protein (CRP) is an acute-phase reactant synthesized by the liver in response to bacterial infection. Serum levels begin to rise within 6-12 hours of acute tissue inflammation. A rapid assay is widely available.

–        Several prospective studies have shown that in adults who have had symptoms for longer than 24 hours, a normal CRP level has a negative predictive value of approximately 100% for appendicitis.

–        Specificity is 50-87% in several series

–        Three studies in adults showed that the combination of a WBC count of less than 10,500 cells/mm3, neutrophilia less than 75%, and a normal CRP level had 99-100% negative predictive value for acute appendicitis (Yang, 2006). One retrospective study of 77 patients older than 60 years found that only 2 had a normal “triple screen” (Yang, 2005).

–        In 1989, Thimsen et al noted that a normal CRP level after 12 hours of symptoms was 100% predictive of benign, self-limited illness.

–        CRP results do not distinguish between various types of bacterial infection.


One study of 500 patients with acute appendicitis revealed that approximately one third reported urinary symptoms, most commonly dysuria or right flank pain. One in 7 patients had pyuria greater than 10 WBC per high power field, and 1 in 6 patients had greater than 3 RBC per high power field. Thus, the diagnosis of appendicitis should not be dismissed due to the presence of urologic symptoms or abnormal urinalysis

Imaging Studies

  • Computed tomography
  • Ultrasonography
  • Abdominal radiography
  • Barium enema study
  • Radionuclide scanning
  • MRI

Clinical diagnostic scores

–        Several investigators have created diagnostic scoring systems in which a finite number of clinical variables is elicited from the patient and each is given a numerical value. The sum of these values is used to predict the likelihood of acute appendicitis.

–        The best known of these is the MANTRELS score, which tabulates migration of pain, anorexia, nausea and/or vomiting, tenderness in the RLQ, rebound tenderness, elevated temperature, leukocytosis, and shift to the left

Treatment guidelines for patients with suspected acute appendicitis

–        Establish intravenous access and administer aggressive crystalloid therapy to patients with clinical signs of dehydration or septicemia.

–        Patients with suspected appendicitis should not receive anything by mouth.

–        Administer parenteral analgesic and antiemetic as needed for patient comfort.

At least 8 randomized controlled studies show that administering opioid analgesic medications to adult and pediatric patients with acute undifferentiated abdominal pain is safe; no study has shown that analgesics adversely affect the accuracy of physical examination. Formerly, the administration of analgesics to patients with acute undifferentiated abdominal pain has historically been discouraged and criticized because of concerns that they render the physical findings less reliable.


  • Antibiotics

These agents are effective in decreasing the rate of postoperative wound infection and in improving outcome in patients with appendiceal abscess or septicemia.

The Surgical Infection Society recommends starting prophylactic antibiotics before surgery, using appropriate spectrum agents for less than 24 hours for nonperforated appendicitis and for less than 5 days for perforated appendicitis. Regimens are of approximately equal efficacy, so consideration should be given to features such as toxicity and cost.

Drug Name of Antibiotics

  • Metronidazole (Flagyl)

Used in combination with aminoglycoside (eg, gentamicin); broad gram-negative and anaerobic coverage. Appears to be absorbed into cells; intermediate metabolized compounds bind DNA and inhibit protein synthesis, causing cell death

  • Gentamicin (Gentacidin, Garamycin)

Aminoglycoside antibiotic for gram-negative coverage. Used in combination with agent against gram-positive organisms and one against anaerobes. Not DOC. Consider if penicillins or other less toxic drugs contraindicated, when clinically indicated, and in mixed infections caused by susceptible staphylococci and gram-negative organisms. Numerous regimens; adjust dose for CrCl and changes in volume of distribution. May be given IV/IM.


  • Wound infection
  • Dehiscence
  • Bowel obstruction
  • Abdominal/pelvic abscess
  • Stump appendicitis – Although rare, approximately 36 reported cases of appendicitis in the surgical stump after prior appendectomy exist
  • Death (rare)