Spotlight Case June 2003

Missed Appendicitis

webmm.ahrq.gov

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Source and Credits

• This presentation is based on June 2003 AHRQ WebM&M Spotlight Case in Surgery

• See the full article at http://webmm.ahrq.gov • CME credit is available through the Web site

– Commentary by: James Adams, MD, Feinberg School of Medicine, Northwestern University

– Editor, AHRQ WebM&M: Robert Wachter, MD– Spotlight Editor: Tracy Minichiello, MD– Managing Editor: Erin Hartman, MS

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ObjectivesAt the conclusion of this educational activity, participants should be able to:

• Appreciate the variable presentation of appendicitis• List complications of missed appendicitis• Understand the advantages and disadvantages of

CT in diagnosing appendicitis• Define anchoring and metacognition and state their

impact on missed diagnoses• List potential strategies to enhance patient safety in

the emergency department (ED)

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Case: Missed Appendicitis

A 37-year-old woman with no past medical history went to ED complaining of vomiting and periumbilical abdominal pain for 6 hours. On physical examination, she was afebrile, BP 110/70, HR 85. Abdomen was soft, with no rebound or guarding. She was diagnosed with gastroenteritis, discharged with antiemetics, and told to return for persistent vomiting, pain, or new fever.

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Abdominal Pain in the ED

• Most common chief complaint in the ED– 6% of the 100 million yearly ED visits

• Appendicitis is the most common surgical cause of abdominal pain– 7% of population affected over a lifetime

• Small percentage of abdominal pain is due to appendicitis– 1%-3% of ED visits for abdominal pain are

appendicitis

McCaig LF, et al. CDC 2002;326:April 22. Graff L, et al. Acad Emerg Med 2000;7:1244-55.

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Challenge of Diagnosing Appendicitis

• Diagnosis uncommon; clinicians accustomed to ruling out rather than ruling in disease

• High incidence of missed diagnoses due to low suspicion – 20%-40% misdiagnoses in some populations

• Implementation of diagnostic algorithm may combat this effect – Reduce misdiagnosis rates to 6%

Naoum JJ, et al. Am J Surg 2002;184:587-9.

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Challenge of Diagnosing Appendicitis

• Classic signs of appendicitis increase likelihood of disease

– Epigastric pain, radiating to RLQ, rebound, fever

• Classic presentation not typical

– WBC count normal in 10%-30%

– Early disease often presents with normal vitals, physical examination

Wagner JM, et al. JAMA 1996;276:1589-94.

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Abdominal CT in Appendicitis• CT can enhance diagnostic accuracy

– Sensitivity 80%-100%

• CT can delay diagnosis– Reserve for men with atypical presentation and

for women in whom pelvic pathology may mimic appendicitis

• CT in low-risk population will lead to increase in false positive readings– Potential increase in unnecessary surgery

Ege G. et al. Br J Radiol 2002;75:721-5. Maluccio MA. et al. Surg Infect 2001;2:205-11.

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Abdominal Pain in the ED

• Maintain suspicion for early disease• Consider CT in appropriate population• Consider inpatient observation• Always provide detailed follow-up and

discharge instructions– Include warning signs and symptoms to prompt

return visit to ED

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Case (cont.): Missed Appendicitis

Patient went to PCP’s office 2 days later with persistent abdominal pain; vomiting had resolved. On physical exam, patient was afebrile, with normal vital signs. Abdomen was diffusely tender, with localization around the umbilicus. Pelvic exam revealed no cervical motion and mild adnexal tenderness. Diagnosis: mittelschmerz vs. ovarian cyst. Transvaginal ultrasound ordered for following week. Patient told to take naproxen for pain.

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“Anchoring”

• Cognitive error due to reliance on diagnostic assumptions and prior reasoning of previous assessments

• Transition of care points are high risk for propagation

• To minimize this type of error, take a step back and think broadly about the case—i.e., apply “metacognition”

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Case (cont.): Missed Appendicitis

The next day, the patient returned to the ED with persistent pain. She was seen by the same ED attending, who then asked a colleague to evaluate the case. This second ED attending performed a pelvic exam and ordered a CT scan of the abdomen and pelvis. CT revealed a perforated appendix.

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Perforated Appendix

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Case (cont.): Missed Appendicitis

The patient was seen by general surgery and it was decided not to take her to the operating room immediately due to the peritonitis. She was admitted and started on IV antibiotics. Her hospital stay was prolonged due to ileus. On hospital day number #8, her WBC count began to rise. A repeat CT scan was obtained.

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Intra-abdominal Abscess

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Case (cont.): Missed Appendicitis

CT revealed an intra-abdominal abscess “the size of an orange.” The patient underwent percutaneous drainage by interventional radiology. On hospital day #13, she was discharged home with a plan to follow-up for elective appendectomy.

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Complications of Perforated Appendix

• Wound infection and dehiscence• Intra-abdominal abscess• Sepsis• Prolonged ileus• Pneumonia• Bowel obstruction• Infertility

Graff L, et al. Acad Emerg Med 2000;7:1244-55. Mueller BA, et al. NEJM 1986;315:1506-8.

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Case (cont.): Missed Appendicitis

Shortly after discharge, the abdominal pain returned. The patient returned to the ED and underwent a repeat CT scan, which revealed a small bowel obstruction. The patient went to the operating room the next day for lysis of adhesions and appendectomy. Eight days later, the patient was discharged home. She has returned to her previous state of health.

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Challenges to Patient Safety in ED

• Excessive cognitive burden

• Time pressure

• Multiple interruptions

• No pre-existing relationship with patients

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• Implement strategies to provide doctors with post-discharge feedback

• Encourage providers to use ED patient safety resources

• Increase teamwork• Improve provider–patient communication

Enhancing Patient Safety in ED

Wears RL, et al. Top Health Information Mgmt. 2002;23:1-12.

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Take-Home Points• Appendicitis is an uncommon but important

cause of abdominal pain in the ED• Presentation is often atypical• Complications of missed or delayed

diagnosis are multiple and morbid• To decrease missed appendicitis, consider

CT scan, inpatient observation, and/or detailed follow-up instructions

• Use CT scan with caution

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Take-Home Points (cont.)

• Avoid “anchoring”– Always question conclusions of previous providers,

particularly as new information accrues

• Consider implementing diagnostic algorithms to ensure that appendicitis is in the differential, even in atypical cases

• “Close the loop” by obtaining follow-up on clinical outcomes