Appendicitis, Acute – Causes, Diagnosis, Treatment, Ongoing care and Clinical pearls



  • Acute inflammation of the vermiform appendix, first described by Reginald Fitz in 1886
  • Arising from the base of the cecum in right lower quadrant (RLQ); can be localized anterior, posterior, medial, lateral to the cecum, as well as in the pelvis
  • Vascular supply by appendicular artery, a branch of the ileocolic artery
  • Most common cause of the acute surgical abdomen


  • Predominant age: 10–30 years:
    • Rare in infancy
  • Predominant sex: Slight male predominance:
    • Ages 10–30: Male > Female (3:2)
    • Age >30: Male = Female


  • 1 case per 1,000 people per year
  • Lifetime incidence 1 in every 15 persons (7%)

Pregnancy Considerations

  • Most common extrauterine surgical emergency
  • 1 in 2,000 pregnancies

Risk Factors

  • Adolescent males
  • Familial tendency
  • Intra-abdominal tumors


1st-degree relative with history of appendicitis increases risk, although no direct genetic link has been found


The initial event inciting appendicitis is thought to be obstruction of the appendiceal lumen. This leads to distention, ischemia, and bacterial overgrowth. Without intervention, most cases of appendicitis will lead to perforation and subsequently abscess formation or generalized peritonitis.


Causes of obstruction:

  • Fecaliths (most common)
  • Lymphoid tissue hyperplasia (in children)
  • Inspissated barium
  • Vegetable, fruit seeds
  • Other foreign bodies
  • Intestinal worms (ascarids)
  • Strictures, fibrosis
  • Neoplasms

Appendicitis, Abdominal pain, X-ray computed tomography, Vermiform appendix, Ectopic pregnancy, Inflammation, male predominance, acute appendicitis,


Diagnosis of acute appendicitis relies on the clinical integration of history, physical exam, and often laboratories and imaging. Scoring systems, including the Alvarado Score and the Pediatric Appendicitis Score, have been developed to help predict the likelihood of acute appendicitis, although diagnosis is still considered a clinical decision.


  • The classic history is vague periumbilical pain, followed by anorexia/nausea/vomiting. Over the next 4–48 hours, pain then migrates to the right lower quadrant.
  • Only 50% of patients present with this classic history.
  • Pain before vomiting (∼100% sensitive)
  • Abdominal pain (∼100%)
  • Anorexia (∼100%)
  • Nausea (90%)
  • Vomiting (75%)
  • Pain migration (50%)
  • Obstipation
  • Atypical symptoms and pain with retrocecal and pelvic appendix

Physical Exam

  • Fever; temp >100.4°F (can be absent)
  • Tachycardia
  • RLQ tenderness
  • Maximal tenderness at McBurney’s point
  • Voluntary and involuntary guarding
  • Cutaneous hyperesthesia at T10–12
  • Rovsing sign: RLQ pain with palpation of left lower quadrant
  • Psoas sign: Pain with right thigh extension (retrocecal appendix)
  • Obturator sign: Pain with internal rotation of flexed right thigh (pelvic appendix)
  • Local and suprapubic pain on rectal exam (pelvic appendix)
  • Pelvic and rectal exams necessary to explore other pathology (pelvic inflammatory disease, prostatitis, etc.)
  • Serial exams can be useful in indeterminate cases.

Pediatric Considerations

  • Decreased diagnostic accuracy
  • Higher fever, more vomiting

Pregnancy Considerations

  • Difficult diagnosis
  • Appendix displaced by gravid uterus

Geriatric Considerations

Decreased diagnostic accuracy, atypical presentations

Diagnostic Tests & Interpretation


  • Leukocytosis: white blood cells (WBC) >10,000/mm3 (70%)
  • Polymorphonuclear predominance or “left shift” (>90%)
  • hCG (if negative, rules out ectopic pregnancy)
  • Urinalysis:
    • Elevated specific gravity
    • Hematuria, pyuria (∼30%)
  • C-reactive protein:
    • Nonspecific inflammatory marker
    • When paired with an elevated WBC can increase the likelihood of appendicitis
  • Drugs that may alter lab results:
    • Antibiotics
    • Steroids


  • Used in cases of suspected appendicitis when the diagnosis is not clear
  • Helpful to detect complications (abscess)
  • Computed tomography (CT) scan: Sensitivity ∼91–98%; specificity 95–99%; imaging modality of choice.
  • CT scan with IV contrast alone provides equivalent information to CT scan with rectal or oral contrast (1)[A].
  • Ultrasound: Viable alternative in pregnant patients, children, and in women with suspected gynecologic pathology (2)[B]. Sensitivity ∼86%; specificity ∼81%. An initial ultrasound and, if negative, a CT scan has been shown to be an effective workup strategy for all patients (3)[B].
  • Plain films: Little utility, nonspecific findings, may visualize fecalith
  • Magnetic resonance imaging: May be helpful in pregnant patients
  • Radioisotope-labeled WBC scans: May be used in patients with indeterminate CT scans and suspected appendicitis as an alternative to observation or surgery

Diagnostic Procedures/Surgery

Diagnostic laparoscopy useful in equivocal cases, especially in fertile women (1)[A]

Pathological Findings

  • Acute appendiceal inflammation
  • Local vascular congestion
  • Obstruction
  • Gangrene
  • Perforation with abscess (15–30%)
  • Fecalith

Differential Diagnosis

  • Gastrointestinal:
    • Gastroenteritis
    • Inflammatory bowel disease
    • Diverticulitis
    • Ileitis
    • Cholecystitis
    • Pancreatitis
    • Intussusception
    • Volvulus
  • Gynecologic:
    • Pelvic inflammatory disease
    • Ectopic pregnancy
    • Ovarian cyst, ovarian torsion
    • Endometriosis
    • Ruptured graafian follicle
  • Urologic:
    • Testicular torsion, epididymitis
    • Kidney stones
    • Prostatitis, cystitis, pyelonephritis
  • Systemic:
    • Diabetic ketoacidosis
    • Henoch Schönlein purpura
    • Sickle cell crisis
    • Porphyria
  • Other:
    • Acute mesenteric lymphadenitis
    • No organic pathologic condition
    • Hernias
    • Psoas abscess
    • Rectus sheath hematoma
    • Epiploic appendagitis
    • Pneumonia (basilar)



First Line

  • Uncomplicated acute appendicitis: Perioperative dose of broad-spectrum antibiotic (4)[A]:
    • Cefoxitin (Mefoxin); cefotetan (Cefotan)
  • Gangrenous or perforating appendicitis:
    • Broadened antibiotic coverage for aerobic and anaerobic enteric pathogens
    • Fluoroquinolone and metronidazole typical
    • Adjust dosage and choice of antibiotic based on intraoperative cultures.
    • Continue antibiotics for 7 days postoperatively or until patient becomes afebrile with normal white blood cell count.

Second Line

  • Ampicillin-sulbactam (Unasyn)
  • Ticarcillin-clavulanate (Timentin)
  • Piperacillin-tazobactam (Zosyn)

Additional Treatment

General Measures

Surgery (appendectomy) is still the standard of care. However, nonoperative management with antibiotics has been studied as an alternative. Some literature suggests that antibiotic therapy alone may be initially as successful as appendectomy, but this approach carries recurrent appendicitis rates of 14–20% in the first year (5). The possibility of recurrence or progression to perforation must be weighed against the potential complications of surgery.

Issues for Referral

All cases of appendicitis require emergent surgical consultation.

Surgery/Other Procedures

  • Inpatient surgery is appropriate measure
  • Patients presenting within 72 hours of onset:
    • Immediate appendectomy; laparoscopic favored unless perforation (6)[A]
    • Drainage of abscess, if present
  • Patients who present late (>4–5 days after symptom onset) may be treated initially with antibiotics, bowel rest, and drainage of any abscess. Later (4–10 weeks) appendectomy can then be performed in this subgroup only.

In-Patient Considerations

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Admission Criteria

All patients with appendicitis should be admitted.

IV Fluids

  • Fluid resuscitation with NS or LR
  • Correct fluid and electrolyte deficits


Preoperative preparation

Discharge Criteria

Tolerating p.o.; return of bowel function; afebrile; normal WBC

Ongoing Care

Follow-Up Recommendations

  • Return to work is usually possible 1–2 weeks following most uncomplicated appendicitis.
  • Restrict activity for 4–6 weeks after surgery: No heavy lifting (>10 lbs) or strenuous physical activity.

Patient Monitoring

Routine visits at 2 and 6 weeks after surgery


n.p.o. before surgery

Patient Education

Contact physician for postoperative development of:

  • Anorexia
  • Nausea
  • Vomiting
  • Abdominal pain
  • Fever
  • Chills


  • Generally uncomplicated course in young adults with unruptured appendicitis
  • Factors increasing morbidity and mortality:
    • Extremes of age
    • Appendiceal rupture
  • Morbidity rates:
    • Nonperforated appendicitis: 3%
    • Perforated appendicitis: 47%
  • Mortality rates:
    • Unruptured appendicitis: 0.1%
    • Ruptured appendicitis: 3%
    • Patients >60 years of age: 50% of deaths from appendicitis
    • Older patients with ruptured appendix: 15%

Pediatric Considerations

  • Rupture earlier
  • Rupture rate: 15–50%

Pregnancy Considerations

Fetal mortality rate: 2–8.5%

Geriatric Considerations

Rupture rate: 67–90%


  • Wound infection
  • Intra-abdominal abscess; lower rate with antibiotic prophylaxis (1)[A]
  • Intestinal fistulas
  • Intestinal obstruction
  • Incisional hernia
  • Liver abscess (rare)
  • Paralytic ileus
  • Pyelophlebitis


1. Mun S, Ernst RD, Chen K et al. Rapid CT diagnosis of acute appendicitis with IV contrast material. Emerg Radiol. 2006;12:99–102.

2. Old JL, Dusing RW, Yap W et al. Imaging for suspected appendicitis. Am Fam Physician. 2005;71:71–8.

3. Poortman P, Oostvogel HJ, Bosma E, Lohle PN, Cuesta MA, de Lange-de Klerk ES, Hamming JF, et al. Improving diagnosis of acute appendicitis: results of a diagnostic pathway with standard use of ultrasonography followed by selective use of CT. J Am Coll Surg. 2009;208:434–41.

4. Andersen BR, Kallehaue FL, Andersen HK. Antibiotics versus placebo for prevention of postoperative infection after appendectomy. Cochrane Database Syst Rev. 2006;(1).

5. Hansson J, Körner U, Khorram-Manesh A et al. Randomized clinical trial of antibiotic therapy versus appendectomy as primary treatment of acute appendicitis in unselected patients. Br J Surg.2009;96:473–81.

6. Sauerland S, Lefering R, Neugebauer EAM. Laparoscopic versus open surgery for suspected appendicitis. Cochrane Database Syst Rev. 2006;(1).

Additional Reading

Anderson SW, Soto JA, Lucey BC, Ozonoff A, Jordan JD, Ratevosian J, Ulrich AS, Rathlev NK, Mitchell PM, Rebholz C, Feldman JA, Rhea JT, et al. Abdominal 64-MDCT for suspected appendicitis: the use of oral and IV contrast material versus IV contrast material only. AJR Am J Roentgenol. 2009;193:1282–8.

Hlibczuk V, Dattaro JA, Jin Z, Falzon L, Brown MD, et al. Diagnostic accuracy of noncontrast computed tomography for appendicitis in adults: a systematic review. Ann Emerg Med. 2010;55:51–59.e1.

Gaitini D, Beck-Razi N, Mor-Yosef D, Fischer D, Ben Itzhak O, Krausz MM, Engel A, et al. Diagnosing acute appendicitis in adults: accuracy of color Doppler sonography and MDCT compared with surgery and clinical follow-up. AJR Am J Roentgenol. 2008;190:1300–6.

See Also (Topic, Algorithm, Electronic Media Element)

Algorithm: Abdominal Rigidity



  • 540.0 Acute appendicitis with generalized peritonitis
  • 540.9 Acute appendicitis without mention of peritonitis
  • 541 Appendicitis, unqualified


  • 85189001 Acute appendicitis (disorder)
  • 196781001 Acute appendicitis with peritonitis (disorder)

Clinical Pearls

  • Classic history of anorexia with periumbilical pain localizing to RLQ is the cornerstone of diagnosis for acute appendicitis.
  • Diagnosis is much more challenging in children, pregnant patients, and the elderly due to varying symptoms and signs.
  • CT of abdomen and pelvis is the diagnostic test of choice, although ultrasound in experienced hands has good sensitivity and avoids radiation exposure.
  • Acute appendicitis is the most common surgical emergency during pregnancy.

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