Appendicitis is the inflammation of the vermiform appendix.
- Lifetime risk: approximately 8%
- 6% of the population gets appendicitis.
- Peak incidence: 10–19 years of age
- Males > females
- The most common acute surgical problem in the pediatric population
- Obstruction of appendiceal orifice (implicated, but not often proven)
- Cause of obstruction varies with age.
- Children and young adults: lymphoid follicular hyperplasia secondary to infection
- Older adults:
- Tumors (benign or malignant)
- Rare: parasites (usually in endemic areas)
Pathophysiology and Clinical Presentation
- Obstruction of appendiceal orifice is the 1st step (presumed).
- Mucus accumulation and luminal distention:
- Bacterial overgrowth (mixed; aerobes and anaerobes):
- Escherichia coli
- Bacteroides fragilis
- Increase in transmural pressure → thrombosis and occlusion of small vessels
- Ischemia and necrosis (gangrene)
- Eventual perforation
- Bacterial overgrowth (mixed; aerobes and anaerobes):
- Usually first 24 hours
- Distention of the appendix stimulates T8–10 afferent nerves.
- Vague periumbilical pain develops.
- Usually after 24 hours
- Invasion of appendiceal wall by bacteria + ischemia
- Propagation of neutrophilic exudate → fibropurulent reaction involving serosal surface
- Peritoneal irritation → localized pain and tenderness
- Affects 13%–20% of cases
- In 65% of cases, symptoms last longer than 48 hours.
- In 20% of cases, symptoms last less than 24 hours.
- More likely with calculus as the obstructing culprit:
- Walled-off perforation: abscess formation
- Free perforation: generalized peritonitis
- Periumbilical pain that later migrates to the right lower quadrant (RLQ)
- Generalized malaise
- Anterior appendix (most common): pronounced localized RLQ pain
- Retrocecal: dull abdominal pain
- Pelvic: dysuria, diarrhea, tenesmus (from bladder and rectal irritation)
- Duration of symptoms: typically 24–48 hours
- Abdominal pain:
- Sudden onset
- Constant, becoming progressively worse
- Exacerbated by movement
- Anorexia, nausea, diarrhea/constipation may or may not be present.
- Symptoms may be vague/atypical in the elderly.
- Adults (eliminate other causes):
- History of inflammatory bowel disease
- History of colorectal cancer/previous colonoscopy
- Reproductive/sexually transmitted diseases in women (rule out pelvic inflammatory disease (PID), ectopic pregnancy)
- Most common in 5–12-year-olds
- Very rare in neonates
- Rule out viral illness:
- History of concurrent or preceding respiratory symptoms
- History of sick contacts with similar symptoms
- Low-grade fever (up to 38.3°C (101°F))
- High fever may indicate late appendicitis/necrosis/perforation.
- Desire to lie still, with difficulty ambulating (common in children)
- Signs of dehydration if prolonged vomiting/anorexia:
- Orthostatic hypotension
- Decreased urinary output
- RLQ tenderness
- Localized rebound tenderness (peritoneal irritation)
- McBurney’s point tenderness: maximal tenderness at 3.8–5.0 cm (1.5–2 in) from anterior iliac spine on a straight line to the umbilicus
- Rovsing’s sign: pain in the RLQ with palpation of the left lower quadrant
- Psoas sign: RLQ pain with passive hip extension (characteristic of retrocecal appendix)
- Obturator sign: RLQ pain with internal hip rotation with a flexed knee (pelvic appendix)
- Generalized peritonitis suggests perforation.
- Not helpful for establishing appendicitis diagnosis
- May be helpful if an alternative diagnosis is suspected
- May be needed in a female if PID is suspected
- Appendicitis (especially pelvic) may also produce tenderness on pelvic exam.
- Complete blood count (CBC): leukocytosis with a left shift
- Inflammatory markers: ↑ erythrocyte sedimentation rate (ESR), C-reactive protein (CRP)
- Chemistry may show dehydration pattern: low K (potassium), low Na (sodium), metabolic alkalosis
- Urinalysis: may show mild pyuria due to proximity of the right ureter
- Pregnancy test: Perform on all females of reproductive age.
- A numerical scale for predicting the likelihood of appendicitis based on clinical and laboratory findings
- Facilitates decision making
- Mnemonic: MANTRELS
|Symptoms||Migratory pain in the right iliac fossa||1|
|Nausea and vomiting||1|
|Signs||Tenderness in the right iliac fossa||2|
|Shift to left||1|
- 0–4: Appendicitis is less likely.
- 5–6: Appendicitis is possible; imaging evaluation needed
- 7–8: Appendicitis is probable → surgical consultation
- 9–10: Appendicitis is highly likely → surgical consultation
Imaging is not required for diagnosis if the Alvarado score is very low (< 3) or high (> 7).
- Computed tomography (CT) scan:
- Highest diagnostic accuracy
- Should be performed with intravenous contrast unless contraindicated (renal failure, allergy)
- Findings of appendicitis:
- Appendiceal diameter > 6 mm (0.24 in) with occluded lumen
- Appendiceal wall thickening > 2 mm (0.08 in)
- Appendiceal wall enhancement
- Periappendiceal fat stranding
- Appendicolith (in about 25% of cases)
- Ultrasound (US):
- Lower diagnostic accuracy than CT
- Operator dependent
- Preferred test in children and pregnant women as it avoids radiation
- Signs of appendicitis:
- Non-compressible appendix
- Appendix diameter > 6 cm (2.4 in)
- Focal pain with pressure from US probe
- Increased echogenicity of surrounding fat
- Fluid in RLQ
- “Target sign”:
- Hypoechoic (fluid-filled lumen)
- Hyperechoic (mucosa/submucosa)
- Hypoechoic (muscularis layer)
- Magnetic resonance imaging (MRI):
- Inferior to CT scan
- An alternative when CT is contraindicated
- Intravenous resuscitation (hydrate and replace electrolytes)
- NPO (nothing by mouth)
- Analgesia, nausea control
- Intravenous antibiotics:
- Cefazolin + metronidazole
- Clindamycin + ciprofloxacin/aztreonam
- Growing evidence that appendicitis can be managed with antibiotics alone
- 90% will initially respond to antibiotics.
- Recurrence rate of 20%–30% in the first year
- Lower rate of wound infections
- Less pain on postoperative day 1
- Shorter hospital stay
- Lower rate of intraabdominal infections
- Shorter operative time
Initial non-operative management:
- Preferred approach as immediate surgery has high risk of complications:
- More extensive surgery (ileocecectomy) may be required
- Risk of postoperative abscess, fistula
- Indicated for contained perforation:
- Cecal phlegmon or abscess > 3 cm (1.18 in) on CT scan
- Stable patient without diffuse peritonitis
- Intravenous antibiotics: broad-spectrum enteric coverage
- Intravenous fluids and bowel rest
- Radiologically guided drainage of an abscess
- Successful (patient is discharged home with 7–10-day course of oral antibiotics):
- ↓ pain
- ↓ fever
- ↓ leukocytosis
- Unsuccessful: rescue appendectomy during the same admission
- Generally recommended 6–8 weeks after successful nonoperative management
- If not performed:
- Up to 30% risk of recurrence during the 1st year
- 10%–29% risk of neoplasm in perforated appendix
- Colonoscopy should also be considered for patients > 40.
- Always indicated for unstable patient with generalized peritonitis/free perforation
- May require more extensive resection (ileocecectomy)
- Requires washout and drainage of peritoneal cavity
- Can also be performed for contained perforation with small phlegmon or abscess (< 3 cm (1.18 in))
- Mortality is low: 0.09%–4%
- Complications of appendectomy:
- Wound infection: 3.3%–10.3%
- Pelvic/abdominal abscess: 9.4%
- Stump appendicitis: if appendix was not completely removed, leaving more than 0.5 cm (0.2 in) stump
- Gastroenteritis: acute self-limited viral illness presenting with abdominal pain, vomiting, and diarrhea. Imaging and labs may be largely normal. Condition is treated supportively with bowel rest and intravenous hydration.
- Mesenteric lymphadenitis: inflammation of mesenteric lymph nodes associated with acute or chronic abdominal pain. Mesenteric lymphadenitis commonly localizes to RLQ because of a large number of lymph nodes in that area. Computed tomography scan/US will show lymphadenopathy.
- Epiploic appendagitis: ischemia/infarction of the colonic fatty appendages. Epiploic appendagitis presents with acute or subacute lower abdominal pain. Computed tomography scan can confirm the diagnosis. Usually, this self-limited illness is treated with oral anti-inflammatory medications.
- Meckel’s diverticulitis: inflammation of Meckel’s diverticulum. The condition may be impossible to clinically distinguish from acute appendicitis as the pain is similar; however, it may be more central or left-sided. Occasionally, there is a history of intermittent lower gastrointestinal bleeding. Computed tomography scan may or may not be diagnostic. Sometimes, diagnosis is made during surgery.
- Right-sided diverticulitis: inflammation of colonic diverticula. Usually left-sided, but right-sided presentation can also occur, especially in young patients and in Asian populations. Patients present with RLQ pain, fever, and change in bowel habits. Diagnosis is made by CT scan.
- Terminal ileitis: inflammation of the terminal ileum that can have an antecedent history of abdominal cramping, weight loss, and diarrhea. The ileitis may be non-specific, due to Crohn’s disease or Yersinia infection. Diagnosis is made acutely by CT scan. Colonoscopy (Crohn’s) and serum antibody titers (Yersinia) can help establish the etiology.
- Right ureteric colic: obstructive stone in the right ureter that presents as intermittent (colicky) pain of the right flank/groin. Urinalysis will show the presence of red blood cells. Diagnosis is established by non-contrast CT scan.
- Urinary tract infection: bacterial infection of the urinary tract in the form of cystitis (bladder infection) or right-sided acute pyelonephritis (kidney involvement). Presents with suprapubic pain and dysuria (cystitis) or right costovertebral angle tenderness and fever (pyelonephritis). Diagnosis is made by urinalysis and CT scan.
- Right-sided ectopic pregnancy: pregnancy in the right fallopian tube. Presents with right-sided abdominal pain. When ruptured, can present with fever, sepsis, and peritonitis. Usually, there is a history of a missed menstrual period. Findings include a positive pregnancy test and pain with cervical manipulation (pelvic exam). Diagnosis is confirmed with pelvic US.
- PID: sexually transmitted infection involving internal reproductive organs, usually in a young adult woman. Pelvic inflammatory disease presents with lower abdominal pain (mostly bilateral), fever, and vaginal discharge. Diagnosis is established with pelvic exam and US.
- Ovarian and fallopian tube torsion: causes acute ischemia of the ovary/fallopian tube. Torsion presents with abdominal pain (RLQ if on the right), fever, and nausea/vomiting. When suspected, a Doppler pelvic US (looking at the blood flow) should be performed. The condition can affect females of both adult and pediatric age.
- Ruptured ovarian cyst (right): fluid or blood released from the cyst causes peritoneal irritation and acute onset of RLQ abdominal pain. Diagnosis is made by pelvic US.
- Martin, R.F. (2020). Acute appendicitis in adults: Clinical manifestations and differential diagnosis. Retrieved 11 December 2020, from https://www.uptodate.com/contents/acute-appendicitis-in-adults-clinical-manifestations-and-differential-diagnosis?search=appendicitis&source=search_result&selectedTitle=2~150&usage_type=default&display_rank=2
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- Smink D., Soybel D.I. (2020). Management of acute appendicitis in adults. Retrieved 11 December 2020, from https://www.uptodate.com/contents/management-of-acute-appendicitis-in-adults?search=appendicitis&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1
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