can appendicitis be missed on a cat scan

Although a CT scan of the abdomen of patients with appendicitis has been reported to have excellent performance characteristics,47,48 2% of patients (105 adults and 13 children) with potentially missed appendicitis in our study had received a CT scan at the index visit.

Case & Commentary: Part 2

Two days later, the patient complained of ongoing stomach pain at her primary care physician’s office; her vomiting had stopped. To get the report, her primary care physician called the emergency room. On exam, she was afebrile with normal vital signs. Her pelvic examination was unremarkable, and she had a diffusely tender abdomen with some localization around the umbilicus. A transvaginal ultrasound was scheduled for the following week. With instructions to take naproxen for the pain, the patient was sent home.

When the information and findings of earlier assessments are incorporated into later diagnostic reasoning, diagnostic presumptions and other people’s earlier reasoning can continue, unquestioned. The cognitive fallacy known as “anchoring” is frequently the cause of errors in emergency departments and in the medical field at large. (10) Assumptions regarding acuity and diagnosis are made in the emergency room based on the findings and evaluations of paramedics, nurses, and other medical professionals. If an initial error is not reevaluated, it may spread and result in delayed diagnosis or even incorrect diagnosis of a serious illness. Transitions in healthcare provide an opportunity for errors to occur because they permit the introduction of “pseudo-information” and “posterior probability error,” in which the evaluation of diagnostic probability is impacted by prior diagnoses. (11).

To reduce cognitive error, the clinician should take a moment to reflect on the case holistically prior to the patient’s final discharge. To avoid such errors, expert clinicians apply “metacognition. Applying this “big picture” assessment can prevent error. (12) The caregivers ask themselves, “Given the same set of facts and circumstances, is there an alternative explanation that may be more accurate? Have all possibilities been taken into account? Are all issues properly addressed?”

Diagnostic error often occurs when patients present atypically. (2) Adverse events correlate with false-negative determinations. By carefully considering the possibility of appendicitis, one can maximize diagnostic sensitivity and improve the diagnostic decision-making process for ED patients experiencing abdominal pain.

Case & Commentary: Part 1

An uninsured 37-year-old woman arrived at the emergency department (ED) with six hours of vomiting and periumbilical abdominal pain. Upon physical examination, her blood pressure measured 110/70 and her heart rate was 85. She was found to be afebrile. Her abdomen was soft, without rebound or guarding. She was diagnosed with gastroenteritis and discharged with antiemetics. She was instructed to come back if she experienced ongoing vomiting, pain, or a fever.

Approximately 0.6 million emergency department visits in the United States occur due to complaints of abdominal pain, making it a common chief complaint in emergency departments. (1,2) Appendicitis is the most common surgical cause of abdominal pain, affecting 7% of people at some point in their lifetime. (2,3) Of all ED patients experiencing abdominal pain, only 1%–3% will develop acute appendicitis, with many of those cases presenting abnormally. As a result, doctors might eventually grow accustomed to ruling out appendicitis rather than ruling it in, which would lower the chance of diagnosing the condition. Clinicians can counteract this effect by implementing formal or informal guidelines that encourage the consideration of extremely morbid diagnoses, such as diabetic ketoacidosis, ectopic pregnancy, and appendicitis. (4) While the frequency of misdiagnosis of appendicitis varies from 2020% to 20400% in certain populations, the application of a diagnostic guideline was found to lower the rate of misdiagnosis to approximately 66% in a single study. (5).

It would be incorrect to believe that the absence of objective symptoms or the presence of unusual laboratory or historical features rules out a serious underlying illness given the difficulty in diagnosing appendicitis. For instance, only a small percentage of appendicitis patients will exhibit the typical abdominal pain history, which moves from the epigastrium to the periumbilical region and finally to the lower right quadrant. While the white blood cell (WBC) count will increase in between 10% and 90% of patients with acute appendicitis, this test is not sensitive or specific enough to diagnose or rule out the illness. (6,7) The risk of appendicitis is increased by the presence of pain in the right lower quadrant, abdominal rigidity, and migration of pain from the periumbilical region to the right lower quadrant. The history and physical examination are useful in evaluating a patient for appendicitis, despite the fact that they are frequently atypical. For instance, appendicitis is unlikely if vomiting occurs prior to the onset of pain or if there is no fever, guarding, or pain in the right lower quadrant.

If doctors wait for distinct, obvious symptoms, they will miss a lot of diagnoses. Although cramping, intermittent pain or muscle soreness from vomiting may be caused by gastroenteritis, severe, ongoing pain should not be expected. This patient did not appear to be exhibiting symptoms of diarrhea, vomiting, nausea, cramping abdominal pain, or fever, which is why the diagnosis should not have been made. Even in cases where vomiting is present, the presence of pain should raise suspicions for serious underlying conditions, such as appendicitis. In cases where there is uncertainty, the physician must determine whether further inpatient monitoring or imaging is necessary, or if the patient can safely go home. In either circumstance, clear discharge instructions should be provided.

A computed tomography (CT) scan can improve the diagnostic precision of appendicitis when there is abdominal tenderness. Nonetheless, surgical consultation shouldn’t be postponed if there is a high suspicion of acute appendicitis. Concerns regarding emergency physicians’ and surgeons’ possible over-reliance on CT scans have been raised, albeit anecdotally and widely. When the diagnosis can be made with confidence or otherwise ruled out, there is no need for the time, cost, or radiation associated with a CT scan. For instance, a confirmatory CT scan is not necessary to diagnose appendicitis in a man exhibiting classic right lower quadrant tenderness and other typical signs and symptoms. Nonetheless, getting a CT scan is appropriate for men whose diagnosis is less certain and women whose ovarian pathology can mimic appendicitis.

While the sensitivity of up to 10% has been reported for CT scans of the appendix (6), in typical practice, the sensitivity is more likely to be 80%-96%. As a result, physicians need to be aware that false negative scans could occur. Conversely, the specificity of appendiceal CT is not perfect. A Bayesian approach is required because the widespread use of CT in low-risk patients will result in a large number of needless appendicectomies and false positive test results. Sometimes, even with a CT report, a period of inpatient or outpatient observation is necessary. The best ways to reduce error are through effective communication and patient education, which includes detailed discharge instructions.

Maintaining suspicion for an early disease, even one that is not yet diagnosable, is the best way to evaluate an ED patient experiencing abdominal pain, and you should educate the patient accordingly. After a general diagnosis of “abdominal pain,” the patient should be appropriately informed about “red flag” symptoms and signs as well as the anticipated course of treatment. Careful instructions must include warning signs of more serious disease if abdominal tenderness is absent and there is no reason for a CT scan or prolonged hospital stay. This means that the initial appointment cannot be considered a failure but rather a success if the patient returns with appendicitis.

“We’re not advocating for the use of CT scans in every instance of abdominal pain,” Mahajan clarifies. Instead, we hope that this finding will help emergency departments and other healthcare providers make decisions about when to follow up with patients and when to request advanced imaging, as the study found that the majority of cases were diagnosed during the repeat visit. “.

According to Mahajan, “many cases of possibly missed appendicitis in children and adults were initially diagnosed as constipation.” It is suggested that in certain cases, the diagnosis of appendicitis may have been misinterpreted as constipation, or the label of constipation may have triggered a cognitive bias known as premature closure, which could have led the healthcare provider to overlook an appendicitis diagnosis. “.

“In this study, we examined patients that initially presented to an emergency department with symptoms of appendicitis, but were not diagnosed at that first presentation,” says the studys lead investigator, Prashant Mahajan, M.D., MPH, a professor and vice-chair of emergency medicine at Michigan Medicine and division chief of pediatric emergency medicine at C.S. Mott Childrens Hospital.

The study, published in JAMA Network Open, highlights that appendicitis is one of the most common surgical emergencies in the United States, but previous data show an appendicitis diagnosis is missed in 3.8% to 15% of children and in 5.9% to 23.5% of adults during an emergency department visit.

“The repeat health care visit could be either again at the emergency department or another health care facility, and the majority of these diagnoses were made within seven days of the initial emergency department visit,” says Mahajan, also a member of the University of Michigan Institute for Healthcare Policy and Innovation.


What abdominal pain does not show up on CT scan?

Examples of conditions that we would not diagnose on CT scan or ultrasound include viral infections (‘the stomach flu’), inflammation or ulcers in the stomach lining, inflammatory bowel disease (such as Crohn’s Disease or Ulcerative Colitis), irritable bowel syndrome or maldigestion, pelvic floor dysfunction, strains …

What is silent appendicitis?

Even deep pressure in the right lower quadrant may fail to elicit tenderness the reason being that the caecum, distended with gas, prevents the pressure exerted by the palpating hand from reaching the inflamed appendix, so it has been called as ‘ silent appendicitis’.

What is commonly misdiagnosed as appendicitis?

Crohn’s disease often causes long-standing symptoms, but up to one-third of patients with ileocecal Crohn’s disease present with initial symptoms so acute that they are misdiagnosed as appendicitis [7].

Can you see a normal appendix on CT scan?

The normal appendix may be visualized on CT scans as a thin-walled tubular structure surrounded by mesentenic fat [6] (Fig. 1). The caliber of the normal appendix should not exceed 6 mm.