The authors of a recent study learned missing appendicitis was more likely to occur among patients with comorbidities, women, and patients who experienced abdominal pain accompanied by constipation.1

“The ED is particularly vulnerable to diagnostic errors due to time-pressured decision-making, lack of complete information, frequent interruptions, and the need for accurate and timely diagnosis,” says Fernanda Bellolio, MD, MS, one of the study’s authors.

Often, decisions are made with inadequate information. “Appendicitis is a good example of a disease that, at the time of presentation to the ED, patients may be in an early and incompletely evolved disease state. That could change quickly,” says Bellolio, a professor of emergency medicine and research chair in the department of emergency medicine at Mayo Clinic in Rochester, MN.

Bellolio and colleagues analyzed insurance claims data from 2019 involving patients who presented to the ED with undifferentiated symptoms associated with appendicitis. Of 123,711 patients who were ultimately diagnosed with appendicitis, it was potentially missed in 6% of adults and 4.4% of children. “Because it is a retrospective analysis, we say these are potentially missed,” Bellolio explains.

Some patients presented more than once to the ED with similar complaints, but it is unclear whether the appendicitis diagnosis could have been made at the time of the first visit. Overdiagnosis puts patients at risk for unnecessary interventions. “However, greater attention has gone into underdiagnosis or missed diagnoses, which may result in morbidity or mortality that could have been avoided with timely diagnosis,” Bellolio suggests.

Bellolio and colleagues set out to pinpoint factors associated with a potentially missed diagnosis of appendicitis in the ED. “We see many patients coming with abdominal pain. We need to identify the minority that will have a surgical pathology like appendicitis,” Bellolio says.

The answer is not always more diagnostic testing. The authors cautioned against overuse of CT scans for abdominal pain patients, particularly for young patients. Even among those who underwent CT scans, there were potentially missed appendicitis cases, Bellolio notes.

The vast majority of the adults with same-day diagnosis underwent CT scans, but most of the missed appendicitis cases had undergone CT scans, too. “We need to weigh the risk and benefits with each patient, and keep our clinical suspicion high,” Bellolio explains.

Most patients with potentially missed appendicitis were constipated. “We noticed that the use of abdominal X-ray was unhelpful and more likely to mislead providers,” Bellolio reports. Seeing stool burden in an X-ray does not mean abdominal pain is caused by constipation. Abdominal X-rays should be used to rule out ingested foreign bodies, says Bellolio, “but otherwise, it is misleading and causes confirmation bias.”

Amy Evans, JD, says missed appendicitis cases usually follow a similar fact pattern. The patient comes to the ED early in the disease process. The ED provider diagnoses gastroenteritis or constipation based on the presence of fecal material on X-rays and/or a patient reporting no recent bowel movements. The patient is discharged with standard follow-up instructions for gastroenteritis or constipation. The patient returns a few days later with a ruptured appendix and peritonitis, requiring an open procedure as opposed to a laparoscopic procedure.

“Liability can be mitigated or prevented through careful discharge instructions,” says Evans, executive vice president of business development and liability claims division at Intercare Insurance Services in Bellevue, WA.

For the best possible defense, these instructions should include directives to return if pain does not resolve in 24 hours, or if the patient develops chill, fever, loss of appetite, nausea, vomiting, or diarrhea. “Detailed discharge instructions with close post-discharge follow-up is important to mitigate risk,” Evans adds.


  1. Mahajan P, Basu T, Pai CW, et al. Factors associated with potentially missed diagnosis of appendicitis in the emergency department. JAMA Netw Open 2020;3:e200612.