Clinical Considerations: Typical Clinical Presentation

Appendicitis initially produces crampy periumbilical pain, corresponding to infection localized to the appendiceal mucosa and muscularis layers. Pain then becomes more localized to the region of the appendix as infection extends into the peritoneal layer. Anorexia, nausea, vomiting, fever, and leukocytosis (with left shift, no eosinophilia) are common.

Physical examination in an older child will often reveal tenderness at McBurney's point. In younger children, localization to the right iliac fossa is all that can be detected. Bowel sounds may be hypoactive in association with appendicitis and absent in the presence of generalized peritonitis.

The cramps of appendiceal obstruction are rarely severe. If an older child cries with abdominal pain, the child probably does not have appendicitis. In infancy, general irritability and a tendency to lay quietly with the hips flexed may be the only indication of pain.

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Clinical Considerations: Atypical Clinical Presentation

A. Atypical clinical presentation related to the position of the appendix

The incidence of atypical clinical presentation of appendicitis ranges from 30 - 45% (4). The relationship of the base of the appendix to the cecum is generally constant. However, the position of the distal end of the appendix is variable. It may be found in a medial, lateral, or caudal position with respect to the cecum, or may be retrocecal. Two thirds of appendices are retrocecal in location; only one third extend in an inferomedial direction (9).

B. Appendicitis in the presence of other illnesses may result in an atypical clinical presentation.

C. Atypical presentation due to complications of perforated appendicitis

Symptoms of the complications of perforated appendicitis may predominate over symptoms of the primary disease.

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Clinical Considerations: Differential Diagnosis

Clinical differential diagnosis may include:

Miscellaneous other entities including torsed mesenteric cyst, peritonitis, constipation, drug ingestion, lower lobe pneumonia, sickle cell disease, and anaphylactoid purpura are other causes of abdominal pain which may be mistaken for appendicitis.

Appendicitis may be recurrent (this is a controversial issue). Approximately 25% of patients with surgically proven appendicitis report a history of prior episodes of abdominal pain that are similar to the one which prompted appendectomy (5).

Other causes of acute recurrent abdominal pain with the clinical picture of an acute abdomen include: hereditary angioedema, porphyria, familial Mediterranean fever, urinary tract infection , gastrointestinal malfunction, and psychophysiological pain.

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Clinical Considerations: Outcome

The preoperative clinical diagnostic accuracy rate ranges from 70 - 78%, with an unnecessary laparotomy rate of 20 - 25% (4,10,11). This rate is higher in women at 35 - 45% (13). Perforation occurs in 20 - 40% of patients with appendicitis (8,12). In children, if the diagnosis is delayed for more than 36 hours, the perforation rate is 65% (2).

With atypical presentation, the false negative appendectomy rate ranges from 15 - 25%, and the complication rate ranges from 15 - 25 % (13). The complication rate associated with removal of a normal appendix is 4 - 15% (13)

Advances in peri-operative care and antibiotics have lowered the mortality rate for appendicitis to less than 1% (5).

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