Appendicitis is inflammation of the appendix. The appendix is a small, thin tube sprouting from the caecum. The appendix becomes inflamed due to infection trapped in the appendix by obstruction at the point where the appendix meets the bowel. The inflammation can quickly proceed to gangrene and rupture. The appendix can rupture and release faecal content and infective material into the abdomen. This leads to peritonitis, which is inflammation of the peritoneal contents.
The peak incidence of appendicitis is in patients aged 10 to 20 years.
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) over time and eventually becomes localised in the RIF. On palpation of the abdomen there is tenderness in McBurney’s point. This is a localised area one third the distance from the anterior superior iliac spine (ASIS) to the umbilicus.
Other classic features are:
- Loss of appetite (anorexia)
- Nausea and vomiting
- Rovsing’s sign (palpation of the left iliac fossa causes pain in the RIF)
- Guarding on abdominal palpation
- Rebound tenderness is increased pain when quickly releasing pressure on the right iliac fossa
- Percussion tenderness is pain and tenderness when percussing the abdomen
Rebound tenderness and percussion tenderness suggest peritonitis, caused by a ruptured appendix.
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.
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 then proceed to an appendicectomy during the same procedure if indicated.
Key Differential Diagnoses of Appendicitis
Consider ectopic pregnancy in girls of childbearing age. This is a gynaecological emergency with a relatively high mortality if mismanaged. A serum or urine bHCG (pregnancy test) to exclude pregnancy is essential in adolescent girls.
Ovarian cysts can cause pelvic and iliac fossa pain, particularly with rupture or torsion.
Meckel’s diverticulum is a malformation of the distal ileum that occurs in around 2% of the population. It is usually asymptomatic, however it can bleed, become inflamed, rupture or cause a volvulus or intussusception. They are often removed prophylactically if identified incidentally during other abdominal operations.
Mesenteric adenitis describes inflamed abdominal lymph nodes. This presents with abdominal pain, usually in younger children. This is often associated with tonsillitis or an upper respiratory tract infection. No specific treatment is required.
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.
Patients with suspected appendicitis need emergency admission to hospital under the surgical team. Older children, for example those aged above 10 years, can often be managed by adult general surgical teams at local hospitals, provided there is a paediatric department in the hospital. Younger children will need to be admitted under paediatric surgeons.
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 (laparotomy).
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)
Last updated August 2019