OBJECTIVE: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged 
as a global pandemic in early 2020 with rapidly evolving approaches to 
diagnosing the clinical illness called coronavirus disease (COVID-19). The 
primary objective of this scoping review is to synthesize current research of 
the diagnostic accuracy of history, physical examination, routine laboratory 
tests, real-time reverse transcription-polymerase chain reaction (rRT-PCR), 
immunology tests, and computed tomography (CT) for the emergency department (ED) 
diagnosis of COVID-19. Secondary objectives included a synopsis of diagnostic 
biases likely with current COVID-19 research as well as corresponding 
implications of false-negative and false-positive results for clinicians and 
investigators.
METHODS: A Preferred Reporting Items for Systematic Reviews and 
Meta-Analyses-Scoping Review (PRISMA-ScR)-adherent synthesis of COVID-19 
diagnostic accuracy through May 5, 2020, was conducted. The search strategy was 
designed by a medical librarian and included studies indexed by PubMed and 
Embase since January 2020.
RESULTS: A total of 1,907 citations were screened for relevance. Patients 
without COVID-19 are rarely reported, so specificity and likelihood ratios were 
generally unavailable. Fever is the most common finding, while hyposmia and 
hypogeusia appear useful to rule in COVID-19. Cough is not consistently present. 
Lymphopenia is the mostly commonly reported laboratory abnormality and occurs in 
over 50% of COVID-19 patients. rRT-PCR is currently considered the COVID-19 
criterion standard for most diagnostic studies, but a single test sensitivity 
ranges from 60% to 78%. Multiple reasons for false-negatives rRT-PCR exist, 
including sample site tested and disease stage during which sample was obtained. 
CT may increase COVID-19 sensitivity in conjunction with rRT-PCR, but guidelines 
for imaging patients most likely to benefit are emerging. IgM and IgG serology 
levels are undetectable in the first week of COVID-19, but sensitivity (range = 
82% to 100%) and specificity (range = 87% to 100%) are promising. Whether 
detectable COVID-19 antibodies correspond to immunity remains unanswered. 
Current studies do not adhere to accepted diagnostic accuracy reporting 
standards and likely report significantly biased results if the same tests were 
to be applied to general ED populations with suspected COVID-19.
CONCLUSIONS: With the exception of fever and disorders of smell/taste, history 
and physical examination findings are unhelpful to distinguish COVID-19 from 
other infectious conditions that mimic SARS-CoV-2 like influenza. Routine 
laboratory tests are also nondiagnostic, although lymphopenia is a common 
finding and other abnormalities may predict severe disease. Although rRT-PCR is 
the current criterion standard, more inclusive consensus-based criteria will 
likely emerge because of the high false-negative rate of PCR tests. The role of 
serology and CT in ED assessments remains undefined.