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).

• Retrocecal or retroileal appendix: A child with acute retrocecal or retroileal appendicitis (appendix deep to distal ileal bowel loops) may walk with exaggerated lumbar lordosis and have a slightly flexed right hip as a result of right psoas muscle spasm. Pain with extension of the right hip with the patient in left lateral decubitus position (psoas sign) and with internal rotation of the thigh (obturator sign) may be found with retrocecal appendicitis. If present, this indicates peritonitis. Absence of bowel sounds or high-pitched, tinkling bowel sounds may indicate bowel obstruction associated with retroiliac appendicitis in children less than six years of age (5).
• The appendix may extend across the midline. When inflamed, the clinical symptoms may mimic those of inflammatory processes involving other organs in the left pelvis, such as the small bowel, sigmoid colon, or left adnexa in female patients.
• Appendix in the right paracolic gutter : Location of the inflamed appendix in the right paracolic gutter typically results in flank pain mimicking acute pyelonephritis or ureteral calculus.. In addition, symptoms resembling those of gastroenteritis may result from colonic irritation.
• Pelvic appendix : Appendicitis in this location may result in pain on rectal examination. Location of the inflamed appendix in the vicinity of the urinary bladder may produce symptoms of urinary frequency resembling those of cystitis.

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

• The typical clinical signs and symptoms of appendicitis may be masked or misinterpreted in neutropenic or immunocompromised patients, such as those with leukemia ; diabetes mellitus; or Crohn’s disease. This may result in delayed diagnosis and its accompanying adverse influence on patient outcome.

C. Atypical presentation due to complications of perforated appendicitis

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

• Generalized peritonitis , a complication of perforated appendicitis, occurs more frequently in younger children. Severe generalized abdominal pain, worsening anorexia, nausea, vomiting, diarrhea, and dehydration occur in association with generalized peritonitis. These findings may be mistaken for severe gastroenteritis, leading to delayed diagnosis. Other factors associated with perforation include fecaliths, temperature greater than 38.6 degrees Celsius, leukocytosis of greater than 14,000 white blood cells per milliliter, and a positive family history of appendicitis. Generalized peritonitis occurs in young children when the appendiceal perforation is not contained by the adjacent ileum and omentum adherent to the inflamed appendix.
• Abscess formation occurs more commonly in children with perforated appendicitis than in adults. Abscess rupture into the bowel lumen occasionally occurs, resulting in spontaneous recovery.
• Small bowel obstruction may result from mass effect related to a periappendiceal abscess. Paralytic ileus is not uncommon. When perforation is associated with small bowel obstruction or ileus, lack of a calcified appendicolith may be a confounding factor resulting in delayed diagnosis.
• Infrequently, intraabdominal sepsis and multi-system organ failure occur with perforated appendicitis in children less than five years of age (5). In the older child, mesenteric venous thrombophlebitis may occur, which may lead to the development of a pyogenic hepatic abscess (2).
• Infants with perforated appendicitis often manifest complications such as intestinal obstruction and systemic sepsis (5).

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Clinical Considerations: Differential Diagnosis

Clinical differential diagnosis may include:

• acute exacerbation of Crohn’s disease,
• mesenteric adenitis which may be viral or due to Yersinia enterocolitica or Y. pseudotuberculosis,
• neutropenic colitis (typhlitis),
• pyelonephritis,
• ureteral calculus,
• pelvic inflammatory disease,
• pelvic tumor,
• ovarian torsion,
• infectious gastroenteritis due to Yersinia enterocolitica or Camphylobacter jejuni,
• infected urachal cyst,
• or Meckel’s diverticulitis.

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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