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Avoiding Misdiagnosis of Appendicitis:Nursing Case Study

Tuesday, 4 March 2014

Patients with abdominal pain represent between 5-10% of all emergency department visits, thus abdominal pain is one of the more common chief complaints. Only a small portion of these patients will have appendicitis but appendicitis is still one of the most common causes of abdominal pain requiring surgical intervention.

The diagnostic dilemmas of abdominal pain are protean and the emergency physician should always ask the critical question

“What is the worst possible diagnosis for my patient?”

Lackadaisical attitudes and wishful thinking about abdominal pain will inevitably result in disasters. Misdiagnosis of appendicitis, for example, is one of the top five most frequent successful malpractice claims against emergency physicians and accounts for 5-15% of the total dollars lost by insurers of emergency physicians.

In the early stages of appendicitis, the lumen of the appendix becomes occluded and the appendix becomes distended with secretions. Visceral nerve fibers that enter the spinal cord at T8-10 are stimulated, causing referred epigastric and periumbilical pain represented by these dermatomes. As appendiceal distention increases, the appendix becomes ischemic and luminal bacteria invade the appendiceal wall. Transmural inflammation with local peritonitis follows, associated with a shifting of maximal pain into the right lower quadrant. As the disease progresses, infarction occurs with perforation, usually between 24-36 hours.

The classical presentation of appendicitis parallels the pathophysiology of the disease process. It begins with a poorly localized, usually periumbilical, constant pain associated with anorexia. As appendiceal distention continues, nausea and vomiting result. Local irritation occurs next and the pain shifts to the right lower quadrant and becomes more acute and sharp. Although the pain usually localizes to the right lower quadrant, it can occur anywhere in the abdomen or pelvis. Next, patients become progressively more toxic and develop fever and chills.

“The classical presentation of acute appendicitis only occurs in approximately 55% of nonpregnant patients with pathologically confirmed appendicitis. With careful complete histories and thorough physical examinations, a diagnostic accuracy of approximately 80% can be achieved; in fact, most misdiagnoses result from careless history-taking and physical examination”(1). Of course, part of the complete history is looking at the previous chart (5). This is especially true with suspected appendicitis, where approximately 30% of patients who are diagnosed with appendicitis have been seen initially by another physician. Previous charts provide objective serial information on temperature, abdominal examination, and WBC.

Males ages 18-50 years provide the most typical presentation and are the easiest to diagnose. In this group, the diagnostic accuracy may be as high as 90%. Other subgroups of patients, such as ovulating females, pregnancy, children, elderly and immunocompromised patients present a greater diagnostic challenge .

Evaluating physicians must be extremely cautious with the group of patients presenting with signs and symptoms only minimally suggestive of appendicitis or in which appendicitis is not considered in the differential. Rusnak et al. developed a profile of the patient most likely to have a missed diagnosis of acute appendicitis on the initial emergency room visit:

1. No “classic” signs and/or symptoms of acute appendicitis.
2. Pain but no nausea or vomiting.
3. No rectal examination performed or documented.
4. Administration of IM narcotic pain medication followed by discharge.
5. Diagnosis of gastroenteritis, despite lack of documentation of the typical features of that disease.
6. No specific documentation on the chart to return for followup examination within 12-24 hours.

There is no definitive test for diagnosing appendicitis. Typically, a great emphasis is placed on the WBC. The WBC is elevated in up to 90% of patients with acute appendicitis but is normal in the other 10% (4,6). Too much emphasis on the WBC can cause serious delays in operative intervention and result in perforation (6). Serial WBC may aid in diagnosis if the second test is performed 4-8 hours after the first (7). Finally, a combination of elevated WBC and neutrophilia greater than 75% appears to be more sensitive than the WBC alone.

If the diagnosis is still uncertain after history, physical examination and laboratory diagnosis, then radiologic examination can often be of help. CT appears to be the most sensitive, specific, and accurate diagnostic modality.

Finally, appropriate consultation with a surgeon is critical. In difficult cases, the surgeon will then have the option of admitting the patient for serial examinations. Observation in the hospital for difficult cases is effective since it does not adversely affect the morbidity and mortality of acute appendicitis and reduces the the incidence of negative laparotomy .

In summary, at times the diagnosis of appendicitis can be difficult. The evaluating physician can minimize delay or misdiagnosis by:

1. Always maintaining a high index of suspicion in all cases of abdominal pain, especially cases with an atypical presentation for appendicitis.
2. Performing a careful and thorough history (including review of previous charts).
3. Performing a careful and thorough physical examination (including rectal and geni-talia) and repeating the examination after 4-6 hours.
4. Performing a WBC with differential and repeating the tests after 4-6 hours.
5. Performing diagnostic radiologic examinations such as CT.
6. Obtaining timely surgical consultation.
7. Admitting the patient for observation.

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