Last reviewed 01/2018
A classical clinical feature of acute appendicitis is abdominal pain, which begins as a vague central discomfort, often thought to be indigestion, and is frequently ignored. It is colicky in nature if the cause is obstructive. After a variable period, usually a few hours, but sometimes 2 or 3 days, very rarely longer, the pain shifts to the right iliac fossa and becomes intense and continuous. Later, with peritonism, it may become continuous.
The central pain is referred and thought to be due to stretching of the appendiceal wall. The visceral innervation of the appendix comes from the 10th thoracic spinal segment; the corresponding dermatome encircles the abdomen at the umbilicus. If the visceral innervation is higher then the mid-line pain will be higher. Some patients have a retrosternal pain that shifts to the iliac fossa. Therefore, the important thing about the early pain is its central location and not its precise level. The later right iliac fossa pain is thought to be due to the first involvement of the parietal peritoneum - somatic pain as opposed to earlier visceral.
Associated symptoms are:
- patient wishes to lie still, often with legs drawn up
- nausea and vomiting after the onset of pain
- infrequently, diarrhoea:
- early and transient as a result of visceral pain
- later if retroileal or pelvic involvement appendix; this is typically prolonged and mucoid
- loss of appetite - often precedes the pain by a few hours - a reasonably sensitive symptom
- constipation - sometimes for a few days before the attack
- testicular pain due to visceral referral of afferent nerve impulses to the same spinal segment
As described in the main menu, the symptoms may be modified by age, pregnancy and the position of the appendix.