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Appendicitis
Aka: Appendicitis, Acute appendicitis
- Epidemiology
- U.S. Appendectomy rates: 300,000 per year (10% are normal appendixes)
- Lifetime Incidence
- Women: 6.7%
- Men: 8.6%
- Incidence Pregnancy
- Antepartum: 6.3 per 10,000 pregnancies
- Up to 1 in 1000 are taken to surgery for possible Appendicitis in pregnancy
- Postpartum: 9.9 per 10,000 postpartum patients
- Pathophysiology
- Appendix is long, thin diverticulum
- Arises from inferior cecum
- Appendicitis course
- Luminal obstruction
- Increased mucous production
- Mucosal Ulceration
- Bacterial Infection and overgrowth
- Increased wall tension, followed by necrosis and perforation
- Appendix Perforation
- Perforation Course
- Pus spills into peritoneal cavity
- Results in peritonitis
- Abscess forms
- Perforation at time of surgery increases with age
- Young patients: 20%
- Elderly: 70%
- Risk Factors
- Decreased Dietary Fiber (high Dietary Fiber protective)
- Ingestion of refined carbohydrates
- Infection
- Viral epidemic
- Amebiasis outbreak
- Bacterial Gastroenteritis
- Precautions
- Extremes of age yield atypical presentations
- McBurney's Point pain occurs in only 33% of children
- Newborns may present only irritable or lethargic, and diagnosis is often delayed until after rupture (80%)
- Elderly often have atypical findings and delayed diagnosis
- Pregnant patients present with atypical Appendicitis symptoms
- Right Upper Quadrant Abdominal Pain in 20% of patients
- Rectal Pain in 45% of cases
- Swadron, Schmitz, Bridwell, Carius in Herbert (2019) EM:Rap 19(3): 12-4
- Observe carefully men with Abdominal Pain
- Consider referred pain from Scrotum
- Initial missed Appendicitis diagnosis approaches 50% (especially at extremes of age)
- Missed Appendicitis is often complicated by appendix perforation
- Gastroenteritis is the most common initial misdiagnosis, when Appendicitis is missed
- Exercise caution in applying the Gastroenteritis diagnosis in Abdominal Pain presentations
- Observation protocol in a stable patient when diagnosis is unclear
- Outpatient with return for recheck in 12 hours for responsible patients (and parents of pediatric patients)
- Hospital observation is recommended when follow-up cannot be assured
- Perforation is rare (2%) in first 36 hours of symptoms, and serial exams over this time is reasonable
- Imaging
- Ultrasound lean pediatric patients first if sonographers and radiologists are experienced with Appendix Ultrasound
- CT Abdomen should be obtained if indicated and other modalities are non-diagnostic (despite radiation risk)
- Risk of missed appendix outweighs risk of radiation exposure when clinical suspicion dictates
- Consider MRI Abdomen in children and pregnant patients
- Documentation
- Clearly document history, examination, patient stability and decision making
- Explain abnormal findings (including labs)
- More likely alternative diagnoses should be explained and fit classic diagnostic criteria
- Gastroenteritis should primarily be Vomiting and Diarrhea without focal tenderness
- Exercise caution in diagnosing Constipation as cause of focal Abdominal Pain
- Discharge Instructions should reflect an unclear diagnosis (as opposed to Constipation)
- Include precautions for return
- Encourage re-evaluation within 24-36 hours if symptoms persist
- References
- Claudius and Kassinove in Herbert (2012) EM:RAP 12(10): 2-3
- Weinstock in Herbert (2018) EM:Rap 18(7): 5-7
- Symptoms
- Anorexia (low predictive value)
- Positive Likelihood Ratio: 1.3 (adults and children)
- Negative Likelihood Ratio: 0.64 (LR- 0.58 in children)
- Test Sensitivity: 84%
- Test Specificity: 66%
- Nausea
- Positive Likelihood Ratio: 0.69 to 1.2
- Negative Likelihood Ratio: 0.7 to 0.84
- Test Sensitivity: 58-68%
- Test Specificity: 40%
- Vomiting
- Positive Likelihood Ratio: 0.92 (LR+ 1.3 children)
- Negative Likelihood Ratio: 1.1 (LR- 0.65 in children)
- Test Sensitivity: 50%
- Test Specificity: 45-69%
- Abdominal Pain (occurs in virtually all cases)
- Predictive value of findings
- Right lower quadrant pain (Most important history finding)
- Positive Likelihood Ratio: 7.3 to 8.5 (LR+ 1.4 in children)
- Negative Likelihood Ratio: <0.28
- Test Sensitivity: 81-96%
- Test Specificity: 53%
- Pain occurs before Vomiting
- Positive Likelihood Ratio: 2.8
- Test Sensitivity: 100%
- Test Specificity: 64%
- Pain migration from Periumbilical Pain to Right Lower Quadrant Abdominal Pain
- Likelihood Ratio: 3.2 to 3.6 (LR+ 1.8 in children)
- Negative Likelihood Ratio: 0.50 (LR- 0.7 in children)
- Course of pain (Classic): Occurs in 50% of cases
- Initial: Crampy Periumbilical Pain for 12-24 hours
- Later: Steady, sharp RLQ Abdominal Pain
- Provocative: Cough or Movement
- Signs
- Typical Presentation
- Low grade fever (38.3 - 39.4 C)
- Positive Likelihood Ratio: 1.9 (LR+1.2 in children)
- Negative Likelihood Ratio: 0.58 (LR- 0.9 in children)
- Test Sensitivity: 67%
- Test Specificity: 69%
- Often absent in elderly
- Abdominal rigidity
- Positive Likelihood Ratio: 3.8
- Negative Likelihood Ratio: 0.82
- Involuntary abdominal guarding
- Positive Likelihood Ratio: 1.8 (LR+ 2.1 in children)
- Negative Likelihood Ratio: <0.54 (LR- 0.47 in children)
- Test Sensitivity: 21-74%
- Test Specificity: 57-84%
- Rebound Abdominal Tenderness (RLQ Abdominal Pain when LLQ pressure is released)
- Positive Likelihood Ratio: 2.03 to 6.3 (LR+ 2.2 in children)
- Negative Likelihood Ratio: <0.86
- Test Sensitivity: 26-63%
- Test Specificity: 69%
- Point tenderness in right lower quadrant (RLQ)
- See McBurney's Point
- RLQ tenderness on pelvic exam or rectal exam
- Decreased or absent bowel sounds
- Positive Likelihood Ratio (children): 3.1
- Negative Likelihood Ratio (children): 0.69
- Perforated Appendix
- Accentuated pain
- Vomiting
- Higher fever and Leukocytosis
- Tender RLQ mass
- Suggests Appendiceal abscess
- Also seen with Phlegmon (Cecum inflammation)
- Extrapelvic Appendix
- Right back muscle inflammed (tender below 12th rib)
- Psoas and Illiopsoas inflammation
- Patient keeps right thigh flexed or rigid extension
- Iliopsoas Test (Psoas Sign)
- Positive Likelihood Ratio: 2.4 (LR+ 3.2 in children)
- Negative Likelihood Ratio: 0.90 (LR- 0.7 in children)
- Test Sensitivity: 16%
- Test Specificity: 95%
- Right Ureter Inflammation (Dysuria or Pyuria)
- Intrapelvic Appendix
- Diffuse Suprapubic Pain
- No abdominal muscle rigidity
- Bladder irritation (Dysuria)
- Rectum irritation (tenesmus)
- Obturator internus inflammation
- Obturator Test
- Palpable tender mass on rectal exam
- Additional exam signs
- Rovsing's Sign
- Right Lower Quadrant Abdominal Pain occurs on palpation of the left lower quadrant
- Positive Likelihood Ratio (children): 3.5
- Negative Likelihood Ratio (children): 0.72
- Psoas Sign (see above)
- Patient in the left lateral decubitus position
- Right lower quadrant pain with hyperextension of the the right hip
- Obturator Sign (Obturator Test)
- Right lower quadrant pain on internal rotation of the flexed right thigh
- Positive Likelihood Ratio (children): 3.5
- Negative Likelihood Ratio (children): 0.73
- Dunphy's Sign
- Increased pain with cough
- Pain provoked by hopping, percussion or coughing
- Positive Likelihood Ratio (children): 1.6
- Negative Likelihood Ratio (children): 0.52
- Labs
- Precautions
- No lab marker has sufficient Test Sensitivity to exclude Appendicitis
- Al-Abed (2014) Am J Surg S0002-9610(14): 00360-2 [PubMed]
- Complete Blood Count: Neutrophilic Leukocytosis
- Poor predictive value (poor sensitivity and Specificity)
- Leukocytes normal in 20-25% of Appendicitis cases
- High Negative Predictive Value
- In children, Likelihood Ratio with WBC <10,000 is 0.22
- Interpretation
- Leukocytes range: 10,000 to 20,000 (in 75% of Appendicitis cases)
- Leukocytosis over 15,000 compels evaluation
- Higher Leukocytosis suggests appendix perforation
- C-Reactive Protein (C-RP)
- Increases within 6-12 hours
- Test Sensitivity for Appendicitis: 76%
- Test Sensitivity improves if C-RP remains normal despite >24 hours of symptoms
- In some studies, normal C-RP at 24 hours had a nearly 100% Negative Predictive Value
- Urinalysis
- Sterile pyuria can occur if appendix is adjacent to ureter
- Do not exclude Appendicitis based on urine alone unless urine findings are definitive
- Differential Diagnosis: General
- See Abdominal Pain
- See Abdominal Pain Causes
- See Right Lower Quadrant Abdominal Pain
- See Periumbilical Abdominal Pain
- Regional ileitis (Crohn's Disease)
- Perforated Duodenal Ulcer
- Meckel's Diverticulitis
- Pelvic Inflammatory Disease
- Differential Diagnosis: Identified after Negative Appendectomy
- Mesenteric adenitis (23%)
- Lymphoid Hyperplasia (10%)
- Gastroenteritis (4%)
- Ovarian Cyst (3%)
- Diagnosis
- Alvarado Score (MANTRELS Score)
- Unreliable - not recommended (misses almost a third of Appendicitis cases)
- Pediatric Appendicitis Score
- Unreliable alone, but better efficacy when combined with Appendix Ultrasound (see Pediatric Appendicitis Pathway)
- Appendicitis Inflammatory Response Score
- No further testing if Appendicitis diagnosis is clear
- Based on history and examination
- Most suggestive findings of Appendicitis
- Adults
- Right Lower Quadrant Abdominal Pain
- Abdominal rigidity
- Radiation of Periumbilical Pain to right lower quadrant
- Children
- Absent or decreased bowel sounds
- Positive Psoas Sign
- Positive Obturator Sign
- Positive rovsing sign
- Imaging
- CT Abdomen with contrast
- Preferred in most cases (except children and pregnancy)
- See CT Abdomen in Appendicitis
- RLQ Abdominal Ultrasound
- See Ultrasound in Appendicitis
- Preferred in children and pregnancy
- Combine with pelvic Ultrasound in female patients (consider Ovarian Torsion evaluation)
- If appendix is not visualized, or high clinical suspicion despite negative Ultrasound
- Appendicitis probability 4.2% if Non-diagnostic Ultrasound and WBC <9k, <65% PMN
- Anandalawar (2015) J Am Coll Surg 220(6): 1010-7 [PubMed]
- Perform other imaging or perform close interval serial examinations
- In children or pregnancy, consider MRI Abdomen
- RLQ Abdominal Ultrasound before Abdominal MRI in children is preferred
- Ultrasound first strategy is faster and more cost-effective
- Despite RLQ Abdominal Ultrasound being inconclusive in 25% of cases
- Imler (2017) Acad Emerg Med 24(5): 569-77 +PMID:28207968 [PubMed]
- MRI Abdomen
- Consider in children, pregnancy
- Eliminates the ionizing radiation risk of CT Abdomen
- However, longer study (10 min) and may require sedation in children
- Test Sensitivity and Test Specificity: 97-100% each
- Kearl (2016) Acad Emerg Med 23(2): 179-85 [PubMed]
- Management: Surgical Management
- Acute Suppurative Appendicitis
- Bacterial coverage
- Typical: Aerobic and anaerobic Gram Negative Rods (e.g. e coli, Klebsiella), Bacteroides
- Uncommon: Enterococcus, Pseudomonas aeruginosa
- Rare: Actinomyces, Candida
- Appendectomy
- Laparoscopic appendectomy is preferred over open appendectomy
- Lower postoperative complications (e.g. Wound Infection), recovery time
- Dai (2017) Gastroenterol J 5(4): 542-53 [PubMed]
- Antibiotic options prior to surgery (continued if perforation found at surgery)
- Metronidazole 500 mg IV q8 hours AND choose one of following
- Ceftriaxone 75 mg/kg IV up to 2 g IV q24 hours OR
- Ciprofloxacin 400 mg IV q12 hours OR
- Levofloxacin 750 mg IV q24 hours
- Carbapenem single agent management (choose one)
- Moxifloxacin 400 mg IV q24 hours OR
- Imipenem 500-1000 mg IV q6 hours OR
- Doripenem 500 mg IV q8 hours
- Avoid antibiotics with growing resistance to gram-negative Anaerobes
- Cefotetan or Cefoxitin
- Ampicillin-sulbactam (Unasyn) and Clindamycin
- Appendicitis with Abscess
- Initial antibiotics as in perforated Appendicitis
- Continue antibiotics until no fever or Leukocytosis
- Percutaneous drainage
- Drain left in place
- Remove drain when cathetergram normal
- Appendectomy follows drainage
- Perforated Appendicitis (esp. with peritonitis or Septic Shock)
- Initial antibiotics
- Piperacillin-Tazobactam (Zosyn) 3.375 to 4.5 g IV q6-8 hours
- Carbapenem single agent management (choose one)
- Moxifloxacin 400 mg IV q24 hours OR
- Imipenem 500-1000 mg IV q6 hours OR
- Doripenem 500 mg IV q8 hours
- Metronidazole 500 mg IV q8 hours AND choose one of following
- Ciprofloxacin 400 mg IV q12 hours OR
- Ceftolozone-Tazobactam 1.5 g IV q8 hours OR
- Ceftazidime-Avibactam 2.5 g IV q8 hours OR
- Aztreonam 1 g IV q8 hours
- Ampicillin 2 g IV q6 hours AND Aminoglycoside (Gentamycin OR Tobramycin)
- Appendectomy and perforated or gangrenous appendix
- Appendectomy wound left open
- Continue antibiotics for 7 days
- If fever, Leukocytosis, or obstipation persist
- Obtain CT Abdomen and Pelvis
- Abscess present
- Percutaneous drainage
- Base antibiotics on Gram Stain and culture
- No abscess
- Consider imipenem 500 mg IV q6 hours
- References
- (2018) Sanford Guide (accessed 7/1/2018)
- Helmer (2002) Am J Surg 183:609 [PubMed]
- Management: Other Regimens
- Appendicitis in Pregnancy (1 case per 1500 births)
- Site of surgical incision is controversial
- Transverse incision at McBurney's Point recommended
- Popkin (2002) Am J Surg 183:20-2 [PubMed]
- Antibiotic only treatment
- Contraindicated if appendicolith, perforation or abscess
- Adult protocol with 73% resolution rate
- Ertapenem 15 mg/kg IV bid (children) up to 1 g IV q24 hours (adults) for 2-4 days
- Then Levaquin 500 mg daily and Metronidazole 500 mg orally tid for 7 days
- Salminen (2015) JAMA 313(23): 2340-8 [PubMed]
- Antibiotic options (older, original protocol)
- Augmentin for 4 days (original study protocol)
- Appendectomy ultimately needed in only 7-12% of cases at 7-30 days and in 12-30% in the next year
- Higher risk of peritonitis (8% versus 2%)
- However limiting antibiotic only strategy to appendix diameter <10mm might reduce that risk
- Longterm outcome from antibiotic-only management
- After 7 years, 39% treated with antibiotics only, required later appendectomy
- Sippola (2020) JAMA Surg 155(4): 283-9 [PubMed]
- References
- Park (2014) Int J Surg 12(9): 897-900 [PubMed]
- Vous (2011) Lancet 377(9777):1573-9 [PubMed]
- Prognosis
- Mortality overall
- Nonperforated: <1%
- Perforated: 5%
- Mortality if age over 75 years: 25%
- Mortality in pregnancy
- Mother: Up to 4%
- Fetus: 43%
- References
- Claudius in Majoewsky (2012) EM:RAP-C3 2(3): 2
- James (1987) Basic Surgical Practice, Hanley, p.218-23
- Benabbas (2017) Acad Emerg Med 24(5): 523-51 [PubMed]
- Old (2005) Am Fam Physician 71:71-8 [PubMed]
- Paulson (2003) N Engl J Med 348:236-42 [PubMed]
- Rothrock (2000) Ann Emerg Med 36:39-51 [PubMed]
- Snyder (2018) Am Fam Physician 98(1): 25-33 [PubMed]
- Wagner (1996) JAMA 276:1589-94 [PubMed]