Appendicitis is inflammation of the appendix. The peak incidence of appendicitis is in patients aged 10 to 20 years. It can occur at any age but is less common in young children and adults over 50 years.
Pathophysiology
The appendix is a small, thin tube arising from the caecum. It is located at the point where the three teniae coli meet (the teniae coli are longitudinal muscles that run the length of the large intestine). There is a single opening to the appendix that connects it to the bowel, and it leads to a dead end.
Pathogens can get trapped due to obstruction at the point where the appendix meets the bowel. Trapping of pathogens leads to infection and inflammation. The inflammation may proceed to gangrene and rupture. When the appendix ruptures, faecal contents and infective material are released into the peritoneal cavity. This leads to peritonitis, which is inflammation of the peritoneal lining.
Signs and Symptoms
The key presenting feature of appendicitis is abdominal pain. This typically starts as central abdominal pain that moves down to the right iliac fossa (RIF) within the first 24 hours, eventually becoming localised in the RIF. On palpation of the abdomen, there is tenderness at McBurney’s point. McBurney’s point refers to a specific area one third of the distance from the anterior superior iliac spine (ASIS) to the umbilicus.
Other classic features are:
- Loss of appetite (anorexia)
- Nausea and vomiting
- Low-grade fever
- Rovsing’s sign (palpation of the left iliac fossa causes pain in the RIF)
- Guarding on abdominal palpation
- Rebound tenderness in the RIF (increased pain when suddenly releasing the pressure of deep palpation)
- Percussion tenderness (pain and tenderness when percussing the abdomen)
Rebound tenderness and percussion tenderness suggest peritonitis, potentially indicating a ruptured appendix.
Diagnosis
Diagnosis is based on the clinical presentation and raised inflammatory markers. Performing a CT scan can be useful in confirming the diagnosis, particularly where another diagnosis is more likely. An ultrasound scan is often used in female patients to exclude ovarian and gynaecological pathology. Ultrasound can also be useful in children, where a CT scan is less appropriate due to the dose of radiation.
Appendicitis is mostly a clinical diagnosis (meaning it is based on signs and symptoms rather than diagnostic tests). Where the diagnosis is unclear, a period of observation may be used, with repeated examinations over time to see whether the symptoms resolve or worsen.
When a patient has a clinical presentation suggestive of appendicitis, but investigations are negative, the next step is to perform a diagnostic laparoscopy to visualise the appendix directly. The surgeon can proceed to an appendicectomy during the same procedure, if indicated.
Key Differential Diagnoses of Appendicitis
Ectopic Pregnancy
Consider ectopic pregnancy in females of childbearing age. This is a gynaecological emergency with a relatively high mortality if mismanaged. A serum or urine human chorionic gonadotropin (hCG) to exclude pregnancy is essential.
Ovarian Cysts
Ovarian cysts can cause pelvic and iliac fossa pain, particularly with rupture or torsion.
Meckel’s Diverticulum
Meckel’s diverticulum is a malformation of the distal ileum that occurs in around 2% of the population. It is usually asymptomatic and does not require any treatment. However, it can bleed, become inflamed, rupture or cause a volvulus or intussusception.
Mesenteric Adenitis
Mesenteric adenitis describes inflamed abdominal lymph nodes. It presents with abdominal pain, usually in younger children, and is often associated with tonsillitis or an upper respiratory tract infection. No specific treatment is required.
TOM TIP: When seeing females of child-bearing age assume they are pregnant until proven otherwise with a pregnancy test. This is especially important in patients with abdominal pain (where ectopic pregnancy is a key differential), or where you are requesting x-rays or CT scans. Serum HCG is typically part of the normal abdominal pain blood panel in A&E.
Appendix Mass
An appendix mass occurs when the omentum surrounds and sticks to the inflamed appendix, forming a mass in the right iliac fossa. This is typically managed conservatively with supportive treatment and antibiotics, followed by appendicectomy once the acute condition has resolved.
Management
Patients with suspected appendicitis need emergency admission to hospital under the surgical team.
Removal of the inflamed appendix (appendicectomy) is the definitive management for acute appendicitis. Laparoscopic surgery is associated with fewer risks and faster recovery compared to open surgery.
Complications of Appendicectomy
- Bleeding, infection, pain and scars
- Damage to bowel, bladder or other organs
- Removal of a normal appendix
- Anaesthetic risks
- Venous thromboembolism (deep vein thrombosis or pulmonary embolism)
TOM TIP: Older children, for example, those aged above 10 years, will often be managed by adult general surgical teams at local hospitals, provided there is a paediatric department in the hospital. This means you may end up visiting the paediatrics ward whilst on your adult surgery rotations. It is worth making friends with paediatric doctors and nurses, who can be very helpful if you are unsure about pain relief or IV fluids prescriptions in children, as this is quite different to adults.
Last updated May 2021
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