Clinical Policy: Evaluation and Management of Suspected Appendicitis

By John M. Howell, MD
ACEP News Contributing Writer

In the January 2010 issue of the Annals of Emergency Medicine, the American College of Emergency Physicians published a clinical policy focusing on critical issues in the emergency department evaluation and management of patients presenting with suspected appendicitis. This is a revision of a clinical policy on abdominal pain that was initially published in 2000.

This clinical policy can also be found on ACEP's Web site, www.acep.org, and will be abstracted on the National Guideline Clearinghouse Web site, www.guidelines.gov.

This clinical policy takes an evidence-based approach to answering three frequently encountered questions related to emergency department decision-making. Recommendations (Level A, B, or C) for patient management are provided based on the strength of evidence using the Clinical Policies Committee's well-established methodology:

Level A recommendations represent patient management principles that reflect a high degree of clinical certainty. Level B recommendations represent patient management principles that reflect moderate clinical certainty. Level C recommendations represent other patient management strategies based on preliminary, inconclusive, or conflicting evidence, or based on consensus of the members of the Clinical Policies Committee.

During development, this clinical policy was reviewed by individual emergency physicians and by individual members of the American Academy of Pediatrics, the American College of Radiology, the Society for Academic Emergency Medicine, the Society for Pediatric Radiology, ACEP's Pediatric Emergency Medicine Section, and ACEP's Emergency Ultrasound Section. Their responses were used to further refine and enhance this policy; however, their responses do not imply endorsement of this clinical policy.

Despite the advent of computed tomography (CT), appendicitis remains a high-frequency malpractice risk for emergency physicians. Appendicitis is the second most common cause of malpractice litigation in children 6 to 17 years old. Even in the hands of the most experienced clinicians, accurately diagnosing appendicitis can be challenging.

Although CT is frequently used to evaluate patients with possible appendicitis, decisions about the use of contrast remain controversial. Also, diagnosing appendicitis in children frequently involves balancing the utility of CT with the theoretical risks of ionizing radiation. As a result, ultrasound is used in some centers to make this diagnosis. However, deciding when to use ultrasound and interpreting the results can be challenging. These and other issues related to the clinical assessment of patients with possible appendicitis are addressed in this policy.

Question 1: Can clinical findings be used to guide decision-making in the risk stratification of patients with possible appendicitis? This question was chosen to determine if there is a role for clinical findings to risk-stratify and guide management and disposition of patients with suspected appendicitis, versus just relying on laboratory and radiologic studies to diagnose and manage these patients.

  • Level A recommendations. None specified.
  • Level B recommendations. In patients with suspected acute appendicitis, use clinical findings (i.e., signs and symptoms) to risk-stratify patients and guide decisions about further testing (e.g., no further testing, laboratory tests, and/or imaging studies), and management (e.g., discharge, observation, and/or surgical consultation).
  • Level C recommendations. None specified.

Question 2: In adult patients with suspected acute appendicitis who are undergoing a CT scan, what is the role of contrast? CT with oral and intravenous (IV) contrast is used in many centers, but waiting for oral contrast to transit the small bowel may prolong emergency department stays, lead to allergic reactions, and cause vomiting. This question was chosen by the Clinical Policies Committee to determine if contrast is necessary, and if so, which type of contrast should be recommended. These management recommendations are intended for patients with suspected appendicitis, not patients with non-specific abdominal pain where a number of diagnoses are considered.

  • Level A recommendations. None specified.
  • Level B recommendations. In adult patients undergoing a CT scan for suspected appendicitis, perform abdominal and pelvic CT scan with or without contrast (intravenous, oral, or rectal). The addition of IV and oral contrast may increase the sensitivity of the CT scan for the diagnosis of appendicitis.
  • Level C recommendations. None specified.

Question 3: In children with suspected acute appendicitis who undergo diagnostic imaging, what are the roles of CT and ultrasound in diagnosing acute appendicitis? There are published articles suggesting that the ionizing radiation associated with abdominal/pelvic CTs is associated with a small increase in lifetime risk of cancer in children. Consequently, some centers use ultrasound as the initial radiologic study in selected children. Ultrasound is not as accurate as CT in definitively excluding acute appendicitis, and there are other factors (e.g., patient peritoneal fat distribution, experience of the radiologist) that influence the effectiveness of ultrasound in diagnosing appendicitis. The recommendations for this question balance diagnostic performance and the risks associated with ionizing radiation.

  • Level A recommendations. None specified.
  • Level B recommendations.
  • Level C recommendations. Given the concern over exposing children to ionizing radiation, consider using ultrasound as the initial imaging modality. In cases in which the diagnosis remains uncertain after ultrasound, CT may be performed. 1. In children, use ultrasound to confirm acute appendicitis but not to definitively exclude acute appendicitis. 2. In children, use an abdominal and pelvic CT to confirm or exclude acute appendicitis.
  • Level C recommendations. Given the concern over exposing children to ionizing radiation, consider using ultrasound as the initial imaging modality. In cases in which the diagnosis remains uncertain after ultrasound, CT may be performed.

Clinical findings can be used to guide decisions about the need for testing and disposition of the patient with suspected appendicitis. When CT is ordered for suspected appendicitis in adults, it is acceptable to scan with or without contrast, although the addition of IV and oral contrast may increase the sensitivity of the CT scan. Ultrasound can be used to confirm acute appendicitis in children, but not to definitively exclude acute appendicitis. If there is a high pre-test clinical suspicion of appendicitis and the ultrasound is either negative or nondiagnostic, CT may be utilized in children.

The policy includes recommendations for future research:

    1) There are limited data on the diagnostic performance of the most recent generations of CT.

    2) A study evaluating a Bayesian approach using ultrasound to diagnose appendicitis in children would be very helpful. For example, such a study would identify the probabilities of appendicitis in children with low, moderate, and high pre-test clinical suspicion.

    3) A study could be constructed to identify clinical factors (e.g., history, selected laboratory tests) that, when combined, can identify and exclude appendicitis (with excellent diagnostic performance) in a large percentage of patients presenting with possible appendicitis.

    4) Research protocols on techniques for limiting ionizing radiation exposure from CT.

    5) A study of the role of magnetic resonance imaging (MRI) in diagnosing appendicitis.

Dr. Howell is director of academic affairs for Best Practices, Inc., and a practicing physician in the department of emergency medicine at Inova Fairfax Hospital in Falls Church, Va.

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