Current challenges in COVID-19 diagnosis: a narrative review and implications for clinical practice

Early diagnosis of coronavirus disease 2019 (COVID-19) is crucial to early treatment and quarantine measures. In this narrative review, diagnostic tools for COVID-19 diagnosis and their main critical issues were reviewed. The COVID-19 real-time reverse transcriptase-polymerase chain reaction (RT-PCR) test is considered the gold standard test for the qualitative and quantitative detection of viral nucleic acid. In contrast, tests can be used for epidemiological surveys on specific communities, including occupational cohorts, but not for clinical diagnosis as a substitute for swab tests. Computed tomography (CT) scans can be useful for the clinical diagnosis of COVID-19, especially in symptomatic cases. The imaging features of COVID-19 are diverse and depend on the stage of infection after the onset of symptoms. CT sensitivity seems to be higher in patients with positive RT-PCR. Conventional chest sensitivity shows a lower sensitivity. An important diagnostic screening tool is ultrasounds, whose specificity and sensitivity depend on disease severity, patient weight, and operator skills. Nevertheless, ultrasounds could be useful as a screening tool in combination with clinical features and molecular testing to monitor disease progression. Clinical symptoms and non-specific laboratory findings may be useful if used in combination with RT-PCR test and CT-scanning.