Acute Appendicitis

Risk Factors/Etiology
  • Appendicitis has a yearly incidence of 1/1000 persons with a lifetime incidence of 7%. There is a slightly increased incidence in males. The highest incidence occurs in 10-30 yr olds, with atypical presentations more common in the very young or very old and women of child-bearing age.
  • Appendicitis is the most common surgical emergency in children.
Clinical Presentation and Diagnoses
  • The classic description is of periumbilical, epigastric, or diffuse dull pain migrating over several hours to McBurney’s point in the right lower quadrant, with the pain changing in character from dull to sharp as the overlying peritoneum becomes inflamed. Peritoneal signs, including involuntary guarding, rigidity and diffuse percussion tenderness may indicate perforation.
  • The pain is less likely to be appendicitis if it has been ongoing for more than 72 h.
  • Associated symptoms which increase the likelihood of appendicitis are anorexia or nausea and vomiting following the onset of abdominal pain. Less specific and less frequently associated symptoms include fever, chills, diarrhea, dysuria and frequency, and constipation. Constipation is a more common symptom in the elderly.
  • The location of the pain is highly variable. 20% of surgically proven appendicitis presents without right lower quadrant pain. Retrocecal appendices or those displaced in pregnancy may cause flank pain. A pelvic appendix may irritate the bladder, resulting in suprapubic pain or dysuria, while a retroileal appendix may irritate the ureter, causing testicular pain. More than two-thirds of appendices lie within 5 cm of McBurney’s point, with more inferior and medial.
  • Frequently associated signs include low-grade temperature, abdominal, rebound, rectal, or cervical motion tenderness. Less commonly present are the psoas and obturator signs or a palpable mass.
  • Associated laboratory values include a WBC count >10,000 and less frequently pyuria (>5 WBC’s/hpf). However, between 10-60% of patients will initially have a normal white count.
  • C-reactive protein (CRP) has been shown to be elevated in several studies when used serially to be helpful in excluding appendicitis, with the diagnoses being rare with two normal values drawn 12 h apart. However, one isolated value is neither sensitive nor specific.
  • Perforation rates are commonly quoted at 20%, with children and elderly incurring perforation >70% of the time. Perforation is the most common malpractice claim for abdominal emergencies and the fifth most expensive claim overall in emergency medicine.
  • Diagnostic studies are merely ancillary and should not replace the clinical impression. Abdominal plain films have little or no utility and should not be routinely ordered, as even the finding of an appendicolith are neither sensitive nor specific for appendicitis. An upright CXR finding of free air is neither sensitive nor specific for perforated appendicitis.
  • The two radiologic studies to consider in cases of diagnostic uncertainty are abdominal ultrasound and helical CT. Ultrasound has reported sensitivity up to 93% and specificity up to 95% and is the preferred test in children and pregnant women. Triple contrast oral, rectal, and IV CT of the abdomen has a sensitivity approaching 100% and specificity of 95-98% when used with the latest CT scanners and experienced readers. Noncontrast helical CT has a sensitivity of 90% and a specificity of 91%.
  • Additionally, some institutions are using the laparoscope to quickly look inside the abdomen. However, this technique often leads to open laparotomy. Less widely available, Technetium-99m labeled WBC scans have a reported sensitivity of 98% and specificity of 95% but are time consuming.
  • Serial abdominal exams over 6-12 h will often aid in the diagnoses as the pain of appendicitis is progressive, leading to the diffusely tender, often rigid abdomen of a perforation. Several studies have shown observation is safe and effective.
  • A urine pregnancy test should always be obtained in all women of child-bearing age.
  • Uncommon mimics of acute appendicitis include DKA and Streptococcal pharyngitis in young children. Other diagnoses to consider include testicular torsion, ruptured ectopic pregnancy, peptic ulcer disease, billiary tract disease, diverticulitis, abscesses, renal colic, pyelonephritis, bowel obstruction, and abdominal aortic aneurysm.
Treatment and Disposition
    1
  • High clinical suspicion: IV fluids if dehydrated, NPO, antibiotics (Cefotetan or Cefoxitan), early surgical consultation with early appendectomy.
  • Moderate clinical suspicion: IV fluids if dehydrated, NPO, surgical consultation, adjunctive test (ultrasound or CT scan). If CT scan or ultrasound positive then early appendectomy and antibiotics. If negative, then observation with serial abdominal exams.
  • Low clinical suspicion: surgical consultation, follow-up in 12 h or earlier if symptoms persist or worsen.
  • Acceptable negative appendectomy rates are approximately 20%.
       
eXTReMe Tracker