ជំងឺកូរ៉ូណាវីរុស២០១៩: Diagnosis

Diagnosis

thumb|Demonstration of a nasopharyngeal swab for COVID-19 testing
thumb|CDC rRT-PCR test kit for COVID-19

The WHO has published several testing protocols for the disease. The standard method of testing is real-time reverse transcription polymerase chain reaction (rRT-PCR). The test is typically done on respiratory samples obtained by a nasopharyngeal swab; however, a nasal swab or sputum sample may also be used. Results are generally available within a few hours to two days. Blood tests can be used, but these require two blood samples taken two weeks apart, and the results have little immediate value. Chinese scientists were able to isolate a strain of the coronavirus and publish the genetic sequence so laboratories across the world could independently develop polymerase chain reaction (PCR) tests to detect infection by the virus. , antibody tests (which may detect active infections and whether a person had been infected in the past) were in development, but not yet widely used. The Chinese experience with testing has shown the accuracy is only 60 to 70%.AFP News Agency (11 April 2020). "How false negatives are complicating COVID-19 testing". Al Jazeera website Retrieved 12 April 2020. The FDA in the United States approved the first point-of-care test on 21 March 2020 for use at the end of that month.

Diagnostic guidelines released by Zhongnan Hospital of Wuhan University suggested methods for detecting infections based upon clinical features and epidemiological risk. These involved identifying people who had at least two of the following symptoms in addition to a history of travel to Wuhan or contact with other infected people: fever, imaging features of pneumonia, normal or reduced white blood cell count, or reduced lymphocyte count.

A study asked hospitalised COVID‑19 patients to cough into a sterile container, thus producing a saliva sample, and detected the virus in eleven of twelve patients using RT-PCR. This technique has the potential of being quicker than a swab and involving less risk to health care workers (collection at home or in the car).

Along with laboratory testing, chest CT scans may be helpful to diagnose COVID-19 in individuals with a high clinical suspicion of infection but are not recommended for routine screening. Bilateral multilobar ground-glass opacities with a peripheral, asymmetric, and posterior distribution are common in early infection. Subpleural dominance, crazy paving (lobular septal thickening with variable alveolar filling), and consolidation may appear as the disease progresses.

In late 2019, WHO assigned the emergency ICD-10 disease codes U07.1 for deaths from lab-confirmed SARS-CoV-2 infection and U07.2 for deaths from clinically or epidemiologically diagnosed COVID‑19 without lab-confirmed SARS-CoV-2 infection.

រោគវិទ្យា

Few data are available about microscopic lesions and the pathophysiology of COVID‑19. The main pathological findings at autopsy are: 
 Macroscopy: pleurisy, pericarditis, lung consolidation and pulmonary oedema
 Four types of severity of viral pneumonia can be observed: 
 minor pneumonia: minor serous exudation, minor fibrin exudation
 mild pneumonia: pulmonary oedema, pneumocyte hyperplasia, large atypical pneumocytes, interstitial inflammation with lymphocytic infiltration and multinucleated giant cell formation 
 severe pneumonia: diffuse alveolar damage (DAD) with diffuse alveolar exudates. DAD is the cause of acute respiratory distress syndrome (ARDS) and severe hypoxemia.
 healing pneumonia: organisation of exudates in alveolar cavities and pulmonary interstitial fibrosis
 plasmocytosis in BAL
 Blood: disseminated intravascular coagulation (DIC); leukoerythroblastic reaction
 Liver: microvesicular steatosis