emDOCs Podcast – Episode 18: Appendicitis… Why we miss it, and how do we improve?

Today on the emDocs cast with Brit Long, MD (@long_brit) and Manpreet Singh, MD (@MprizzleER) we cover one awesome post: Appendicitis – Why we miss it, and how do we improve?


Part 1: Appendicitis… Why we miss it, and how do we improve?

– Appendicitis is missed in 4% of pediatric patients and 6% of adults.

– Highest incidence of appendicitis at 10-30 years. The appendix is attached to the posteromedial wall of the cecum, and the tip can migrate to other locations.

– Inflammation occurs due to intraluminal obstruction and subsequent engorgement from mucosal secretion distal to the obstruction. Eventually, bacteria multiply behind the obstruction, invade the appendix mucosa, and cause tissue necrosis, organ infarction, and perforation.

 

– Classic symptoms include right lower quadrant abdominal pain, anorexia, and nausea/vomiting.  Pain typically starts in central abdomen around the umbilicus with migration to right lower quadrant.

 

– Labs and imaging have varying sensitivity and specificity. CT is reliable for diagnosis.

 

– Several risk scores available to determine need for further evaluation, but each has limitations and biases.

 

– Cognitive biases: “Cognitive shortcuts used to aid our decision making”. Cognitive error responsible for 30% of all errors in the ED.

– Prototypical error: A cognitive bias that puts the clinician at risk for missing appendicitis when right lower quadrant abdominal pain is not present.

– Search Satisfaction and confirmation bias: Clinicians are more likely to miss the diagnosis of appendicitis when they identify other pathologies first.

 

Other Populations:

– Children 0-5 years have 1.5 times risk of missed appendicitis with greater risk of rupture. Poor communication in symptoms, failure to obtain appropriate imaging all contribute to misdiagnosis.

  • Omission bias: tendency to judge harmful actions as worse or less moral than equally harmful inactions.

 

– Women with abdominal pain are 1.68 times more likely than men to have a missed diagnosis of appendicitis. Many conditions that cause RLQ in women (ectopic pregnancy, ovarian torsion, PID, TOA, UTI, and pyelonephritis).

  • Multiple alternative bias: many options of differential diagnosis lead to uncertainty, so physician reverts to smaller subset with which they are familiar.

 

– Pregnant women are a subset of the female population especially at risk for missed appendicitis. Even though it is the most common non-obstetric surgical emergency during pregnancy, the diagnostic accuracy of appendicitis is lowest in the 2nd trimester at 64% and highest in the 3rd trimester at 88%. The high rate of misdiagnoses likely stems from the clinician’s temptation to anchor on the patient being pregnant and provide a pregnancy-related diagnosis.

  • Anchoring bias: tendency to rely too heavily on one piece of information in decision-making.
  • Omission bias can also occur when testing.

 

– Elderly: Patients older than 50 years account for 1-in-12 cases of appendicitis, yet they have a perforation rate of 28.6% as compared to 11.6% for the prototypical 10–30 year-old patients. The differential for older adults must additionally include problems such as acute mesenteric ischemia, abdominal aortic aneurysm, aortic dissection, and intestinal volvulus. These diagnoses must be considered because atypical presentations of abdominal pain are more the rule than the exception due to the distinct physiology of older adults.

– Black patients: Black adults with appendicitis are 1.14 times more likely to be misdiagnosed than white adults. The study that produced these results did not provide an explanation or hypothesis for this finding, however, racial and ethnic disparities are appreciated throughout healthcare and ED care. Black patients have longer ED waiting times as compared to non-black patients, black patients are assigned lower triage acuity scores than white patients, and black patients are more often treated at safety net hospitals that typically have fewer resources and higher patient volume.

  • There are likely many cognitive biases and institution-wide disparities affecting the discrepancy between black and non-black rates of missed appendicitis. As EPs, we can close the gap in diagnostic error by acknowledging that we are missing a disproportionate number of cases in this population.
  • Implicit bias: attitudes or stereotypes that are not accessible through introspection that affect understanding, actions, and decisions in an unconscious matter.

 

– For every 100 return visits to the ED for abdominal pain, one-third of them will be due to diagnostic error, and 2 will be for missed appendicitis. Once appendicitis begins, given time, it invariably leads to perforation which can be complicated by peritonitis or sepsis.

– Lowering the rate of missed appendicitis in the ED can be accomplished through improving our awareness of cognitive biases that affect our medical decision making, being mindful of the populations especially at risk for this missed diagnosis, and utilizing all labs and imaging at our disposal when suspicion for appendicitis is high.


Pearls

#1: Utilize prediction scoring tools: AIR score for high risk patients, Alvarado score for dischargeable patients.

#2: Don’t be afraid to utilize CT imaging for intermediate risk patients, including pregnant women and children.

#3: Train yourself to consider appendicitis in “outlier” populations: children, pregnant women, older adults, and black patients. 

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