The COVID-19 pandemic has had a rapidly evolving impact on the U.S. healthcare system. Several studies have shown that ED imaging volume decreased substantially during the COVID-19 pandemic [3,4,6]. This contrasts with the pre-pandemic trend in ED imaging, particularly CT, which had been increasing for the past decade [14-16], as convincing data has shown that early CT diagnosis of certain conditions, such as appendicitis and uncomplicated diverticulitis, reduces hospital resource use and improves patient outcomes [17,18]. There are several potential reasons why ED CT volume decreased during the COVID-19 pandemic, as one would expect the incidence of diseases requiring an abdominopelvic CT in the ED should remain constant or increased. Our data demonstrates that patients with higher acuity conditions usually requiring surgery and/or hospitalization (e.g., appendicitis, small bowel obstruction, complicated diverticulitis) were still being diagnosed by CT at the same rate as before COVID-19. However, patients with uncomplicated diverticulitis, a lower acuity disease that can often be treated as an outpatient, were no longer presenting to the ED for CT scanning.
This paradigm may be explained by understanding the history of abdominal CT utilization in the ED to diagnose diverticulitis. In 1984, Hulnick et al. published a series of 43 consecutive patients imaged with CT at New York University (NYU) Medical Center between 1979 and 1983 [19]. Following this publication, Ferris Hall, writing in an editorial in Radiology stated “ . . . no evidence is provided showing that CT scans alter treatment, expedited or obviated surgery, shortened hospital stay or reduced complication” [20]. Almost 30 years later, Pandharipande et al documented that CT changed the diagnosis of 67% of patients who underwent CT in the ED for suspected diverticulitis [21].
Over this 30-year time frame, the speed, availability and resolution of CT increased and barriers to performing a CT in the ED steadily decreased. The number of patients scanned increased; and the “emergency” barium enema was eliminated from our diagnostic algorithms. However, with the onset of COVID-19, a new barrier to CT scanning was abruptly inserted into the risk/benefit calculation. Now patients and clinicians had to factor the risk of COVID-19 exposure in the ED and clinicians had to factor in the diversion of CT resources away from other COVID-19 related triage.
The fact that CT for uncomplicated diverticulitis decreased during COVID-19, but the use of CT for complicated diverticulitis, appendicitis, and small bowel obstruction was unchanged suggests an interaction between symptom acuity and perceived risks/barriers to imaging that patients and/or clinicians balance when deciding if imaging is necessary. The American Academy of Family Physicians (AAFP) recommendations for diagnosis and management of acute diverticulitis from 2013 state that “imaging is not necessary in most patients with mild symptoms” [22]. The ACR appropriateness criteria from 2019 agrees [23]. It may be that provider willingness to recommend a CT scan for mild symptoms dropped in the face of higher perceived imaging risk. It is also possible that health care providers were more comfortable empirically treating patients with a prior history of diverticulitis without imaging rather than risking COVID-19 exposure during an ED visit. And of course one must consider that patients with mild symptoms may have chosen not to seek care at all.
It is also important to note that while the number of abdominopelvic CTs positive for uncomplicated diverticulitis dropped significantly, there was not a corresponding increase in abdominopelvic CTs positive for complicated diverticulitis. This suggests that while patients with diverticulitis may have delayed presentation to the ED in the face of risks associated with COVID-19 exposure, this possible delay did not result in a change in disease severity at the time of presentation.
This study has several limitations. One is its retrospective design, allowing for correlational analysis only. A second limitation is the size of the study, which uses data from a single health system. Romero et al recently reported that during the COVID-19 pandemic, fewer patients presented with acute appendicitis to the ED, and those who did presented at a more severe stage [24]. Our data did not corroborate this conclusion. Possible explanations include small sample size, disparate patient populations and different clinical courses for appendicitis versus diverticulitis.
An additional limitation is that our timeframe for analysis starts with presentation to the ED. We do not know how many patients were triaged towards or away from the ED based on recommendations from their primary care providers or other providers. As discussed above, this may have had a large impact on the number and severity of cases that did present to the ED. Finally, this study was designed assuming no interaction between diverticulitis incidence and COVID-19 infection. While there has been no data to suggest a causative relationship, COVID-19 is known to affect the gastrointestinal system as many patients do present with gastrointestinal symptoms such as nausea, vomiting or diarrhea [25].
In conclusion, our data suggest that the decrease in abdominopelvic CT scans during the COVID-19 pandemic can be at least partially attributed to a decrease in imaging of lower acuity patients. Our data support the claim that patients with higher acuity abdominal pain did eventually undergo CT in the ED and that possible delayed presentation, at least for patients with diverticulitis, did not result in an increase in disease severity at the time of presentation. These results help explain the marked reduction in the use of CT in the ED during the COVID-19 pandemic and may help to define future strategies for imaging resources utilization. For example, as health care systems and patients have rapidly expanded their use of telemedicine, it may be useful to consider the use of an ED telemedicine consult prior to ED presentation for patients with specific complaints who are concerned about coming the ED, in order to help triage lower risk patients to reduce exposure risk and decongest the ED in times of high resource use. In addition, health care providers’ experience with reduced reliance on imaging during COVID may prompt renewed discussions about the most appropriate use of CT in the ED and may lead to empiric treatment of patients with suspected uncomplicated diverticulitis without first having patients undergo a CT scan.