Rosen & Barkin's 5-Minute Emergency Medicine Consult (67 page)

BASICS

• Most common abdominal emergency
  
• Acute obstruction of appendiceal lumen results in distension followed by organ ischemia, bacterial overgrowth, and eventual perforation of the viscus
  
• Pain migration:
  
  • Periumbilical pain: Appendiceal distension stimulates stretch receptors, which relay pain via
    visceral
    afferent pain fibers to 10th thoracic ganglion.
    
  • RLQ pain: As inflammation extends to surrounding tissues, pain occurs owing to stimulation of
    parietal
    nerve fibers and localizes to position of appendix.
    

• 28–57% misdiagnosis in patients <12 yr (nearly 100% in patients <2 yr)
  
• 70–90% perforation rate in children <4 yr
  
• Perforation correlates strongly with delayed diagnosis.
  

• Decreased inflammatory response
  
• 3 times more likely to have perforation owing to anatomic changes
  
• Diagnosis often delayed owing to atypical presentations
  

• Slightly higher rate in 2nd trimester compared to 1st/3rd/postpartum periods
  
• Increased perforation rate (25–40%), highest in 3rd trimester
  
• RLQ pain remains the most common symptom
  
• 7–10% fetal loss, up to 24% in perforated appendicitis
  

• Luminal obstruction of appendix
  
• Appendiceal lumen becomes distended, inhibiting lymphatic and venous drainage.
  
• Bacterial invasion of wall, with edema and blockage of arterial blood flow
  
• Perforation and spillage of contents into peritoneal cavity, causing peritonitis (usually 24–36 hr from onset)
  
• May wall off and form abscess
  
• Gram-negative rods and anaerobic organisms predominate
  

DIAGNOSIS

• Abdominal pain: Primary symptom:
  
  • Normal location:
    
    • RLQ pain
      
    • 35% of patients have appendix located within 5 cm of “normal” location.
      
  • Retrocecal appendix (28–68%):
    
    • Back pain
      
    • Flank pain
      
    • Testicular pain
      
  • Pelvic appendix (27–53%):
    
    • Suprapubic pain
      
    • Urinary or rectal symptoms
      
  • Long appendix (<0.2%):
    
    • Inflamed tip may cause pain in RUQ or LLQ.
      
    • Anorexia
      
    • Vomiting
      
• Change in bowel habits: Diarrhea (33%), constipation (9–33%)
  
• Classic presentation (<75% adults):
  
  • Initially periumbilical pain
    
  • Followed by anorexia (1st symptom in 95%) and nausea
    
  • Localizes to RLQ (1–12 hr after onset)
    
  • Finally, vomiting with fever
    

• Presentations often nonspecific and difficult to localize (<50% have classic presentation)
  
• Anorexia, vomiting, and diarrhea more common (half-eaten meal hours before complaints of pain may more accurately indicate duration of symptoms)
  
• Observe child before exam for subtle indicators of local inflammation:
  
  • Limping gait
    
  • Hesitation to move or climb
    
  • Flexed right hip
    

• Vital signs:
  
  • Often normal
    
  • Fever: Normal to mild elevation (<1°F) initially, increases with perforation
    
• Abdominal exam:
  
  • Tenderness at McBurney point (1/3 of distance from right anterior iliac spine to umbilicus)
    
  • Guarding:
    
    • Voluntary guarding early owing to muscular resistance to palpation
      
    • Involuntary guarding (rigidity) later as inflammation progresses and perforation occurs
      
  • Rebound:
    
    • Pain with any rapid movement of peritoneum (e.g., bumping stretcher)
      
  • Specific signs (less useful in pediatrics):
    
    • Rovsing sign:
      Pain in RLQ when palpating LLQ
      
    • Psoas sign:
      Increased pain on extension of right hip with patient lying on her or his left side, owing to inflamed appendix touching iliopsoas muscle.
      
    • Obturator sign:
      Pain with passive internal rotation and flexion of right hip
      
• Rectal exam:
  
  • Limited value: May localize tenderness/mass
    
• Pelvic exam:
  
  • Important to differentiate gynecologic disease
    
  • Vaginal discharge and/or adnexal tenderness or mass suggests gynecologic disease.
    
  • Cervical motion tenderness when present suggests PID, but can be seen in up to 25% of women with appendicitis
    
• Patient position:
  
  • Supine or decubitus with legs (particularly the right) drawn up
    
  • Prefer not to move
    
• Shuffling gait—known as “appy walk”
  

Almost all children have generalized abdominal tenderness with some rigidity.

• Enlarging uterus displaces appendix upward and laterally.
  
• Hyperemesis gravidarum and other nonsurgical causes of vomiting should not cause abdominal tenderness.
  

Typical signs of peritonitis may be absent in elderly.

• Suggestive history and physical exam sufficient to establish preoperative diagnosis and warrant surgical consultation
  
• Tests listed below may be used to assist in diagnosis
  
• Atypical cases: Repeat serial exams in conjunction with some of the tests listed below is effective, with decreased rates of negative appendectomies and no increase in rates of perforation
  

• CBC:
  
  • WBC >10,000, with left shift (80%)
    
  • Normal WBC does
    not
    exclude diagnosis
    
• C-reactive protein:
  
  • Overall sensitivity 62%, specificity 66%
    
  • May not be elevated early (<12 hr)
    
  • Increased sensitivity with serial measurements
    
• Urinalysis:
  
  • Generally normal
    
  • Mild pyuria, bacteriuria, or hematuria (25–30%)
    
  • Pyuria present if inflamed appendix lies near ureter or bladder
    
• Pregnancy test for females of child-bearing age
  

• Unnecessary when diagnosis is clear
  
• Most helpful in female patients of child-bearing age where diagnosis is often unclear
  
• Abdominal radiographs—not recommended
  
• US: Sensitivity 86–90%; specificity 92–95%:
  
  • Noncompressible appendix 6 mm anteroposterior (AP) diameter
    
  • Presence of appendicolith
    
  • Periappendiceal fluid/mass
    
  • Limited by obesity, bowel gas, retrocecal appendix, and operator
    
  • Negative study of limited use
    
• CT: Sensitivity 91–100%; specificity 94–97%:
  
  • Highest yield using oral and rectal contrast with focused appendiceal technique (5 mm cuts from 3 cm above cecum extending distally 12–15 cm)
    
  • Fat stranding (100%)
    
  • Appendix 6 mm in diameter (93%)
    
  • Focal cecal apical thickening
    
  • Defines appendiceal masses (phlegmon vs. abscess)
    
  • Best study for finding alternative diagnoses
    
  • Nonvisualized appendix does not rule out appendicitis
    
• MRI: Sensitivity 97–100%, specificity 92–94%:
  
  • Appendix 7 mm in diameter
    
  • Periappendiceal fat stranding
    
  • Advantages: Lack of ionizing radiation, excellent safety profile of gadolinium contrast agents
    
  • Disadvantages: High cost, limited availability, lengthy exam, lack of radiologist familiarity in appendicitis
    
  • No gadolinium in early pregnancy (class C drug)
    

American College of Radiology recommends US followed by CT as needed for suspected appendicitis

• Laparoscopy:
  
  • Diagnostic and therapeutic use
    
  • Gross pathology may be absent with positive microscopic findings
    
• Open appendectomy
  
• Percutaneous drainage
  

• Gastroenteritis
  
• Meckel diverticulum
  
• Epiploic appendicitis
  
• Crohn's disease
  
• Diverticulitis
  
• Volvulus
  
• Abdominal aortic aneurysm
  
• Intestinal obstruction
  
• UTI
  
• Pyelonephritis
  
• PID
  
• Ectopic pregnancy
  
• Ovarian cyst/torsion
  
• Tubo-ovarian abscess
  
• Endometriosis
  
• Renal stone
  
• Testicular torsion
  
• Mesenteric adenitis
  
• Henoch–Schönlein purpura
  
• Diabetic ketoacidosis
  
• Streptococcal pharyngitis (children)
  
• Biliary disease
  

TREATMENT

• Airway, breathing, and circulation management (ABCs)
  
• Fluid resuscitation with LR or 0.9% NS
  

• IV fluids, correct electrolyte abnormalities
  
• Immediate surgical consult for convincing history and physical exam:
  
  • Laparoscopic versus open technique
    
  • Negative appendectomy rate of 10% in males and 20% in females
    
  • Percutaneous drainage, IV antibiotics, bowel rest and possible interval appendectomy in 6–8 wk in appendiceal abscesses
    
• Perioperative antibiotics
  
• NPO
  
• Order CT if palpable mass is present in RLQ to define phlegmon versus abscess
  
• If diagnosis is uncertain, send serial labs, observe, and repeat exams (6–10% negative appendectomy rate with observation protocols)
  
• Analgesics:
  
  • Administration of analgesics, including narcotics, does not adversely affect abdominal exam or mask pathology