- Clinical science
Appendicitis refers to acute inflammation of the appendix, and is the most common cause of acute abdomen requiring emergency surgery. It typically presents with periumbilical pain, which migrates to the right lower quadrant (RLQ), associated with fever, vomiting, anorexia, and malaise. While appendicitis is primarily a clinical diagnosis, raised inflammatory markers and imaging may be useful. The most crucial aspect of treatment is timely intervention (laparoscopic or conventional open appendectomy) to prevent progression to perforation and sepsis, as well as antibiotics.
- Common cause of acute abdomen
- Lifetime risk: ∼ 8%
- Peak incidence: 10–19 years of age
Epidemiological data refers to the US, unless otherwise specified.
- Obstruction of appendiceal lumen by:
- Stasis of mucus and fluid → bacterial growth and local inflammation → rising intraluminal pressure → vascular compromise → ischemia → necrosis → perforation and peritonitis
- Early: mucosal hyperemia with edema and ulceration due to obstruction of the appendix; reversible phase
- Suppurative: transmural spread of infection within the appendix
- Gangrenous: diffuse inflammatory changes in the entire appendiceal wall produce intramural arterial (and venous) thromboses; leading to ischemia, necrosis, and, eventually, a gangrenous appendix
- Spontaneously resolving: relief of symptoms once the cause of obstruction is spontaneously expelled from the appendiceal lumen
- Recurrent appendicitis: repeated episodes of RLQ pain; inflamed appendix histopathologically confirmed after appendectomy
- Chronic appendicitis: persistent RLQ for at least a 3-week duration, with no other possible cause identifiable; relief of symptoms post-appendectomy and histopathological confirmation of appendicitis
- Nonspecific symptoms
- Abdominal pain: classical presentation
Signs of appendicitis
- rebound tenderness caused upon suddenly ceasing deep palpation of the RLQ:
- McBurney point tenderness: an area one-third of the distance from the right anterior superior iliac spine to the umbilicus (in the RLQ)
- Rovsing's sign: deep palpation of the LLQ causes RLQ referred pain
- Psoas sign: RLQ pain with extension of the right leg against resistance (secondary to inflammation of a retrocecal appendix)
- Obturator sign: RLQ pain with flexion and internal rotation of the right leg
The key symptom in appendicitis is right lower quadrant pain!References:
- Acute appendicitis is often a clinical diagnosis.
- Laboratory tests
- Abdominal ultrasound ;: non-compressible and enlarged appendix (> 6–8 mm)
- Abdominal CT scan (∼ 98% sensitivity): periappendiceal streaking and enlarged appendix
Abnormal urine analysis does not necessarily rule out appendicitis!
Appendicitis is a clinical diagnosis. Further examination, such as blood tests and imaging, is not essential to diagnosis but may be considered if the diagnosis is uncertain!References:
Physiological structure of the vermiform appendix
- Length: ∼ 2–20 cm (average ∼ 7 cm)
- Diameter: < 6–8 mm (average ∼ 5 mm)
- Layers from inside to outside:
- Lumen → single layered high columnar epithelium → lamina propria mucosa with numerous lymphoid tissue → lamina muscularis mucosa → submucosa → stratum circulare muscularis (circular muscle layer) → stratum longitudinale muscularis (longitudinal muscle layer) → serosa
Changes in appendicitis
- Infiltration of the tissue with leukocytic granulocytes
- Depending on the stage of pathology, possible ulceration and wall necrosis
Colon cancer in the elderly may mimic acute appendicitis!References:
The differential diagnoses listed here are not exhaustive.
- Conservative therapy is considered in exceptional cases or if findings are unclear ("soft" signs).
- Bowel rest (keep patient NPO), IV fluid therapy, and observation
- Antibiotics; with anaerobic and gram negative cover (e.g., cefazolin and metronidazole)
Suspected appendicitis warrants surgical intervention!
- Surgical approach may be laparoscopic or open and is decided on a case-by-case basis
Gangrenous perforation (10% of cases)
- Clinical features
- Definition: abscess involving the area around the appendix as a result of a concealed perforation
- Clinical features
- Diagnosis: CT scan
- Small abscess → bowel rest, IV antibiotic therapy followed by interval appendectomy after 6–8 weeks
Larger abscess → percutaneous drainage with catheter and bowel rest, IV antibiotic therapy
- When the fistula from the catheter closes → interval appendectomy
- Multicompartmental abscess → prompt surgical drainage
We list the most important complications. The selection is not exhaustive.
- Uncomplicated appendicitis with adequate management (surgical intervention) has an excellent prognosis.
- Perforation and peritonitis: ∼ 1% mortality
- Up to 20% of patients are found to have a normal appendix following surgery.
- Elderly patients (> 60 years old) have a poorer prognosis.
Appendicitis in children
- Children are rarely able to localize the origin of their pain.
- Indirect signs: bending the right hip joint in supine position, weakened abdominal wall reflexes in the RLQ, reduced abdominal breathing
Appendicitis in pregnancy
- Atypical (higher) pain localization: As the uterus expands during pregnancy, the appendix may be pushed up into the RUQ of the abdomen. The position of the appendix may shift in this case, and the typical RLQ pain may not be present.
- Perforated appendix is associated with higher risk of fetal loss.
- Ultrasound is diagnostic procedure of choice
Children, the elderly, and pregnant women are at higher risk of perforation!
Appendicitis in older patients
- Chronic and atypical history
- Pressure (instead of pain) in right iliac fossa
- Low-grade fever (not always present)
- Subtle abdominal guarding
- Reduced sensitivity to pressure point tests