Test Catalog

Test ID: SCOVT    
Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), RNA Detection, ddPCR, Tissue

Useful For Suggests clinical disorders or settings where the test may be helpful

Detection of severe respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19) in formalin-fixed, paraffin-embedded tissue

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus is a positive-sense, single-stranded RNA virus that causes coronavirus disease 2019 (COVID-19). Like other coronaviruses that infect humans, SARS-CoV-2 can cause both upper and lower respiratory tract illness. Symptoms can range from mild (ie, the common cold) to severe (ie, pneumonia) in both healthy and immunocompromised patients. SARS-CoV-2 transmission occurs primarily via respiratory droplets. As the disease progresses, the viral load tends to decrease in the upper respiratory tract, at which point, lower respiratory tract specimens (eg, sputum, tracheal aspirate, bronchoalveolar fluid, transbronchial biopsy, wedge biopsy of lung, autopsy lung specimen) would be more likely to have detectable SARS-CoV-2. Infection of other tissue has been reported.


The SARS-CoV-2 RNA detection in formalin-fixed and paraffin-embedded (FFPE) tissue by droplet digital polymerase chain reaction (ddPCR) assay will be used to detect the nucleocapsid N1 and N2 target sequences of SARS-CoV-2 virus in FFPE surgical and autopsy tissue. The identification of SARS-CoV-2 in surgical tissue may aid in the diagnosis of COVID-19 and may lead to a better understanding of unusual disease presentations. Detection of SARS-CoV-2 in deceased patients (autopsy tissue) may similarly confirm a suspected diagnosis among individuals with clinical or pathologic manifestations of COVID-19 (ie, pulmonary, cardiac) and may increase understanding of SARS-CoV-2 pathobiology.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Not applicable

Interpretation Provides information to assist in interpretation of the test results

This test will be reported as positive, negative, or indeterminate. An "indeterminate" result indicates that the presence or absence of severe respiratory syndrome coronavirus 2 (SARS-CoV-2 RNA) in the specimen could not be determined with certainty after repeated testing in the laboratory. This could be due to reverse transcriptase polymerase chain reaction (RT-PCR) inhibition or very low viral load. Submission of a new specimen for testing is recommended.


Test results should always be considered in the context of patient's clinical history, physical examination, and epidemiologic exposures when making the final diagnosis.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

The assay is adapted from an qualitative severe respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA detection assay that has received FDA emergency use authorization (EUA), and it is modified by the performing laboratory for qualitative detection of SARS-CoV-2 RNA present in formalin-fixed and paraffin-embedded (FFPE) tissue.


The sensitivity of the assay is dependent on the timing of the specimen collection (in relation to symptom onset) and the quality, quantity, and type of specimen submitted. This test is not normalized to the size of the submitted tissue per section.


The test is specific for detection of SARS-CoV-2. Therefore, negative results do not exclude the possibility of infection with other respiratory viruses.


Negative results do not rule out coronavirus disease 2019 (COVID-19) in patients and should not be used as the sole basis for treatment or other patient management decisions. Result should be correlated with patient's history and clinical presentation.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Zhu N, Zhang D, Wang W, et al: A novel coronavirus from patients with pneumonia in China, 2019. N Engl J Med. 2020 Feb;382(8):727-733. doi: 10.1056/NEJMoa2001017

2. Holshue ML, DeBolt C, Lindquist S, et al: First case of 2019 novel coronavirus in the United States. N Engl J Med. 2020 Mar 5;382(10):929-936. doi: 10.1056/NEJMoa2001191

3. Loeffelholz MJ, Tang YW: Laboratory diagnosis of emerging human coronavirus infections-the state of the art. Emerg Microbes Infect. 2020;9(1):747-756. doi.org/10.1080/22221751.2020.1745095

4. Liu X, Feng J, Zhang Q, et al: Analytical comparisons of SARS-COV-2 detection by qRT-PCR and ddPCR with multiple primer/probe sets. Emerg Microbes Infect. 2020 Dec;9(1):1175-1179

5. Suo T, Liu X, Feng J, et al: ddPCR: a more accurate tool for SARS-CoV-2 detection in low viral load specimens. Emerg Microbes Infect. 2020 Dec;9(1):1259-1268