Appendicitis

Aka: Appendicitis

1. Epidemiology
   1. Lifetime Incidence
      1. Women: 25%
      2. Men: 12%
2. Pathophysiology
   1. Appendix is long, thin diverticulum
      1. Arises from inferior cecum
   2. Appendicitis course
      1. Luminal obstruction
      2. Mucosal Ulceration
      3. Bacterial infection
   3. Appendix Perforation
      1. Perforation Course
         1. Pus spills into peritoneal cavity
         2. Results in peritonitis
         3. Abscess forms
      2. Perforation at time of surgery increases with age
         1. Young patients: 20%
         2. Elderly: 70%
3. Risk Factors
   1. Decreased Dietary Fiber (high Dietary Fiber protective)
   2. Ingestion of refined carbohydrates
   3. Infection
      1. Viral epidemic
      2. Amebiasis outbreak
      3. Bacterial Gastroenteritis
4. Precautions
   1. Extremes of age yield atypical presentations
      1. McBurney's Point pain occurs in only 33% of children
      2. Newborns may present only irritable or lethargic
   2. Observe carefully men with Abdominal Pain
5. Symptoms
   1. Anorexia (low predictive value)
      1. Likelihood Ratio: 1.1
      2. Test Sensitivity: 84%
      3. Test Specificity: 66%
   2. Nausea
      1. Test Sensitivity: 58-68%
      2. Test Specificity: 40%
   3. Vomiting
      1. Test Sensitivity: 50%
      2. Test Specificity: 45-69%
   4. Abdominal Pain (occurs in virtually all cases)
      1. Predictive value of findings
         1. Right lower quadrant pain (Most important history finding)
            1. Likelihood Ratio: 8.4
            2. Test Sensitivity: 81-96%
            3. Test Specificity: 53%
         2. Pain occurs before Vomiting
            1. Test Sensitivity: 100%
            2. Test Specificity: 64%
         3. Pain migration from Periumbilical Pain to Right Lower Quadrant Abdominal Pain
            1. Likelihood Ratio: 3.6
      2. Course of pain (Classic): Occurs in 50% of cases
         1. Initial: Crampy Periumbilical Pain for 12-24 hours
         2. Later: Steady, sharp RLQ Abdominal Pain
         3. Provocative: Cough or Movement
6. Signs
   1. Typical Presentation
      1. Low grade fever (38.3 - 39.4 C)
         1. Test Sensitivity: 67%
         2. Test Specificity: 69%
         3. Often absent in elderly
      2. Involuntary abdominal guarding or rigidity
         1. Likelihood Ratio: 1.59
         2. Test Sensitivity: 21-74%
         3. Test Specificity: 57-84%
      3. Rebound abdominal tenderness
         1. Likelihood Ratio: 2.03 (RLQ Abdominal Pain when LLQ pressure is released)
         2. Test Sensitivity: 26-63%
         3. Test Specificity: 69%
      4. Point tenderness in right lower quadrant (RLQ)
         1. See McBurney's Point
      5. RLQ tenderness on pelvic exam or rectal exam
   2. Perforated Appendix
      1. Accentuated pain
      2. Vomiting
      3. Higher fever and Leukocytosis
      4. Tender RLQ mass
         1. Suggests Appendiceal abscess
         2. Also seen with Phlegmon (Cecum inflammation)
   3. Extrapelvic Appendix
      1. Right back muscle inflammed (tender below 12th rib)
      2. Psoas and Illiopsoas inflammation
         1. Patient keeps right thigh flexed or rigid extension
         2. Iliopsoas Test (Psoas Sign)
            1. Test Sensitivity: 16%
            2. Test Specificity: 95%
      3. Right Ureter Inflammation (Dysuria or Pyuria)
   4. Intrapelvic Appendix
      1. Diffuse Suprapubic Pain
      2. No abdominal muscle rigidity
      3. Bladder irritation (Dysuria)
      4. Rectum irritation (tenesmus)
      5. Obturator internus inflammation
         1. Obturator Test
      6. Palpable tender mass on rectal exam
7. Lab
   1. Complete Blood Count: Neutrophilic Leukocytosis
      1. Poor predictive value (poor sensitivity and Specificity)
         1. Leukocytes normal in 25% of Appendicitis cases
      2. Interpretation
         1. Leukocytes range: 10,000 to 20,000 (in 75% of Appendicitis cases)
         2. Leukocytosis over 15,000 compels evaluation
         3. Higher Leukocytosis suggests appendix perforation
8. Differential Diagnosis
   1. See Abdominal Pain
   2. See Abdominal Pain Causes
   3. See Right Lower Quadrant Abdominal Pain
   4. See Periumbilical Abdominal Pain
   5. Regional ileitis (Crohn's Disease)
   6. Perforated Duodenal Ulcer
   7. Meckel's Diverticulitis
   8. Pelvic Inflammatory Disease
9. Diagnosis
   1. No further testing if Appendicitis diagnosis is clear
      1. Based on history and examination
   2. RLQ abdominal ultrasound
      1. Signs suggestive of Appendicitis
         1. Outer appendix diameter (cross-section) >= 6 mm
      2. Signs suggestive of perforated appendix
         1. Loculated pericecal fluid
         2. Phlegmon
         3. Appendiceal abscess
         4. Pericecal fat
      3. Efficacy
         1. Accuracy for acute Appendicitis: 71-97%
         2. High sensitivity for perforated appendix
      4. Identifies alternative diagnoses
      5. Causes of false positive ultrasounds
         1. Meckel's Diverticulum
         2. Pelvic Inflammatory Disease
         3. Endometriosis
         4. Cecal Diverticulitis
         5. Inflammatory Bowel Disease
   3. CT Abdomen with contrast (helical CT most accurate)
      1. Focused below lower pole of right Kidney
      2. Efficacy
         1. Test Sensitivity: >87%
         2. Test Specificity: >95%
         3. Accuracy: 93-98%
         4. Negative Predictive Value: 95%
         5. References
            1. Fefferman (2001) Radiology 220:691-5
      3. CT does not seem to improve diagnosis of Appendicitis
         1. Study finds that CT overall did not offer benefit
         2. Also CT prolonged emergency room and hospital stays
         3. CT with contrast may provide better accuracy
         4. Perez (2003) Am J Surg 185:194-7
      4. Signs suggestive of Appendicitis
         1. Fat streaking
         2. Appendix exceeds 6 mm in diameter
         3. Fluid filled peripheral enhancing tubular structure
         4. RLQ inflammation and no normal appendix identified
         5. Appendix wall thickening
10. Management: Helmer study protocol
    1. Acute Suppurative Appendicitis
       1. Cefotetan 25 mg/kg IV preoperatively
       2. Appendectomy
    2. Appendicitis with Abscess
       1. Initial antibiotics as in perforated Appendicitis
          1. Continue antibiotics until no fever or Leukocytosis
       2. Percutaneous drainage
          1. Drain left in place
          2. Remove drain when cathetergram normal
       3. Appendectomy follows drainage
    3. Perforated Appendicitis
       1. Initial antibiotics
          1. Gentamicin 7 mg/kg IV or Levofloxacin 500 mg IV and
          2. Metronidazole 500 mg IV q6 hours
       2. Appendectomy
          1. Non-perforated: No additional Management
          2. Perforated or gangrenous appendix
             1. Appendectomy wound left open
             2. Continue antibiotics for 7 days
             3. If fever, Leukocytosis, or obstipation persist
                1. Obtain CT Abdomen and Pelvis
                2. Abscess present
                   1. Percutaneous drainage
                   2. Base antibiotics on Gram Stain and culture
                3. No abscess
                   1. Consider imipenem 500 mg IV q6 hours
    4. References
       1. Helmer (2002) Am J Surg 183:609
11. Management: Specific Circumstances
    1. Appendicitis in Pregnancy (1 case per 1500 births)
       1. Site of surgical incision is controversial
       2. Transverse incision at McBurney's Point recommended
       3. Popkin (2002) Am J Surg 183:20-2
12. Prognosis
    1. Mortality overall
       1. Nonperforated: <1%
       2. Perforated: 5%
    2. Mortality if age over 75 years: 25%
13. References
    1. James (1987) Basic Surgical Practice, Hanley, p.218-23
    2. Old (2005) Am Fam Physician 71:71-8
    3. Paulson (2003) N Engl J Med 348:236-42
    4. Rothrock (2000) Ann Emerg Med 36:39-51
    5. Wagner (1996) JAMA 276:1589-94