Appendicitis

Appendicitis is a condition characterised by inflammation of the appendix. While mild cases may resolve without treatment, most require removal of the inflamed appendix, either by laparotomy or laparoscopy. Untreated, mortality is high, mainly due to peritonitis and shock. more...

Causes

The cause of appendicitis is generally unknown, but the leading theory is that obstruction of the appendiceal orifice is the inciting factor. Obstruction may come from fecal matter lodged in the appendix, impaction of mucous, a small tumor (such as a carcinoid), or even a small blood clot. Viral infections, which can cause ulceration of the lining, can also lead to obstruction of the appendix through enlargement of lymph nodes in its walls, a possible explanation for seasonal variations in rates of appendicitis and clustering of cases. Regardless of the cause, obstruction of the appendix may lead to progressive appendiceal distension. This distension increases the pressure within the appendix, which in turn impairs its blood supply. Deprived of blood, the appendix loses the ability to fight infection and fecal bacteria begin to grow out of control. Although spontaneous recovery can rarely occur, with time and lack of treatment the walls of the appendix eventually become gangrenous from the infection and lack of blood flow. As bacteria begin to leak out through the dying walls, pus forms within and around the appendix (suppuration). The end result of this cascade is appendiceal rupture causing peritonitis, which may lead to septicemia and eventually death.

Although the model described above is traditionally taught in medical schools, histories of patients operated for appendicitis do not often correlate well with such a single disease progression. Specifically, those with atypical histories have findings at surgery that are consistent with a suppurative process that starts at the onset of symptoms and then smolders. Patients with typical histories may have findings suggesting resolution. Histories to suggest rupture of the appendix while patients are being diagnostically observed are exceedingly rare.

Thus appendicitis is now considered by some to behave as two distinct disease processes, typical and atypical (or suppurative). Approximately 2/3 of patients with appendicitis have typical histories, and findings suggest a virus or mild obstruction as a cause. In the 1/3 with atypical histories, an early suppurative process begins at the clinical onset, and severe unremitting obstruction is the likely cause. In any case, early operation is the best treatment for either type of appendicitis.

Signs, symptoms and findings

Appendicitis can be classified into two types, typical and atypical. The pain of typical acute appendicitis usually starts centrally (periumbilical) before localising to the right iliac fossa (the lower right side of the abdomen). There is usually associated loss of appetite and fever. Nausea, or vomiting may or may not occur. These classic signs and symptoms are more likely the younger the patient. Older patients (beyond their teenage years) may present with only one or two. Diagnosis is easier in typical acute appendicitis and surgery removes a swollen, inflamed appendix with little or no suppuration (pus) if operated early (within 24 hours of onset).

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