Appendicitis

Aka: Appendicitis

1. Epidemiology
   1. Lifetime Incidence
      1. Women: 6.7%
      2. Men: 8.6%
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
   5. Additional exam signs
      1. Rovsing's Sign
         1. Right Lower Quadrant Abdominal Pain occurs on palpation of the left lower quadrant
      2. Psoas Sign
         1. Patient in the left lateral decubitus position
         2. Right lower quadrant pain with hyperextension of the the right hip
      3. Obturator Sign (Obturator Test)
         1. Right lower quadrant pain on internal rotation of the flexed right thigh
      4. Dunphy's Sign
         1. Increased pain with cough
7. Lab
   1. Precautions
      1. No lab marker has sufficient Test Sensitivity to exclude Appendicitis
      2. Al-Abed (2014) Am J Surg S0002-9610(14): 00360-2 [PubMed]
   2. Complete Blood Count: Neutrophilic Leukocytosis
      1. Poor predictive value (poor sensitivity and Specificity)
         1. Leukocytes normal in 25% of Appendicitis cases
      2. High Negative Predictive Value
         1. In children, Likelihood Ratio with WBC <10,000 is 0.22
      3. 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
   3. C-Reactive Protein (C-RP)
      1. Increases within 6-12 hours
      2. Test Sensitivity for Appendicitis: 76%
         1. Test Sensitivity improves if C-RP remains normal despite >24 hours of symptoms
         2. In some studies, normal C-RP at 24 hours had a nearly 100% Negative Predictive Value
   4. Urinalysis
      1. Sterile pyuria can occur if appendix is adjacent to ureter
      2. Do not exclude Appendicitis based on urine alone unless urine findings are definitive
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. Alvarado Score (MANTRELS Score)
      1. Unreliable - not recommended (misses almost a third of Appendicitis cases)
   2. Pediatric Appendicitis Score
      1. Unreliable alone, but better efficacy when combined with Appendix Ultrasound (see Pediatric Appendicitis Pathway)
   3. No further testing if Appendicitis diagnosis is clear
      1. Based on history and examination
10. Imaging
    1. CT Abdomen with contrast (preferred in most cases)
       1. See CT Abdomen in Appendicitis
    2. RLQ Abdominal Ultrasound
       1. See Ultrasound in Appendicitis
       2. If appendix is not visualized, or high clinical suspicion despite negative Ultrasound
          1. Perform other imaging or perform close interval serial examinations
          2. In children or pregnancy, consider MRI Abdomen
       3. RLQ Abdominal Ultrasound before Abdominal MRI in children is preferred
          1. Ultrasound first strategy is faster and more cost-effective
          2. Despite RLQ Abdominal Ultrasound being inconclusive in 25% of cases
          3. Imler (2017) Acad Emerg Med 24(5): 569-77 +PMID:28207968 [PubMed]
    3. MRI Abdomen (consider in children)
       1. Eliminates the ionizing radiation risk of CT Abdomen
       2. However, longer study (10 min) and may require Sedation in children
       3. Test Sensitivity and Test Specificity: 97-100% each
       4. Kearl (2016) Acad Emerg Med 23(2): 179-85 [PubMed]
11. Management: Helmer study protocol
    1. Acute Suppurative Appendicitis
       1. Cefotetan 25 mg/kg IV preoperatively (or similar agent such as Imipenem)
       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 [PubMed]
12. Management: Other Regimens
    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 [PubMed]
    2. Antibiotic only treatment
       1. Augmentin for 4 days
       2. Appendectomy ultimately needed in only 7-12% of cases at 7-30 days and in 12-30% in the next year
       3. Higher risk of peritonitis (8% versus 2%)
          1. However limiting antibiotic only strategy to appendix diameter <10mm might reduce that risk
       4. References
          1. Park (2014) Int J Surg 12(9): 897-900 [PubMed]
          2. Vous (2011) Lancet 377(9777):1573-9 [PubMed]
13. Precautions
    1. Initial missed diagnosis approaches 50% (especially at extremes of age)
       1. Often complicated by appendix perforation
    2. Observation protocol in a stable patient when diagnosis is unclear
       1. Outpatient with return for recheck in 12 hours for responsible patients (and parents of pediatric patients)
       2. Inpatient observation is recommended when follow-up cannot be assured
    3. Imaging
       1. Ultrasound lean pediatric patients first if your ultrasonographers and radiologists are experienced with Appendix Ultrasound
       2. CT Abdomen should be obtained if indicated and other modalities are non-diagnostic (despite radiation risk)
          1. Risk of missed appendix outweighs risk of radiation exposure when clinical suspicion dictates
    4. Documentation
       1. Clearly document history, examination, patient stability and decision making
          1. Explain abnormal findings (including labs)
       2. More likely alternative diagnoses should be explained and fit classic diagnostic criteria
          1. Example: Gastroenteritis should primarily be Vomiting and Diarrhea without focal tenderness
    5. References
       1. Claudius and Kassinove in Majoewsky (2012) EM:RAP 12(10): 2-3
14. Prognosis
    1. Mortality overall
       1. Nonperforated: <1%
       2. Perforated: 5%
    2. Mortality if age over 75 years: 25%
15. References
    1. Claudius in Majoewsky (2012) EM:RAP-C3 2(3): 2
    2. James (1987) Basic Surgical Practice, Hanley, p.218-23
    3. Old (2005) Am Fam Physician 71:71-8 [PubMed]
    4. Paulson (2003) N Engl J Med 348:236-42 [PubMed]
    5. Rothrock (2000) Ann Emerg Med 36:39-51 [PubMed]
    6. Wagner (1996) JAMA 276:1589-94 [PubMed]