Which test is used to confirm COVID-19 positive case?

JIPMER Nursing Officer - 2020

Applied Microbiology & Infection control

Easy

Appeared in: JIPMER Nursing Officer - 2020

Explanation

RT-PCR (Reverse Transcription Polymerase Chain Reaction) is the 'gold standard' for diagnosing an active COVID-19 infection.
This molecular test works by directly detecting the specific genetic material (RNA) of the SARS-CoV-2 virus from a patient's sample.
Due to its high sensitivity and specificity, it is considered the most reliable confirmatory test for the presence of the virus.

Option A: HRCT is an imaging test that assesses lung damage. While it can show patterns typical of COVID-19 pneumonia (like ground-glass opacities), these findings are not specific to the virus and can be caused by other conditions.
Option B: D-Dimer is a blood test that measures a protein fragment related to blood clot dissolution. It is a marker for complications like coagulopathy in severe COVID-19, not a diagnostic test for the virus itself.
Option D: A Chest X-ray is used for general screening of lung issues like pneumonia. It has low sensitivity in early COVID-19 and lacks the specificity to confirm the infection, as other pathogens can cause similar X-ray findings.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Confirmatory diagnostic tests for COVID-19 as background academic context rather than a clinical decision trigger.
It is crucial for nurses to differentiate between tests for diagnosis, screening, and severity assessment to provide accurate patient education and ensure appropriate care pathways are followed.
A nurse must be able to explain to a patient and their family why an RT-PCR test is necessary for confirmation, even if other tests like a Chest X-ray already show signs of pneumonia.
What if? If a patient with strong clinical symptoms of COVID-19 has a negative RT-PCR test, a false negative should be considered. This can occur due to improper sample collection, testing too early, or a low viral load. A repeat test or a clinical diagnosis based on other findings (like HRCT) might be warranted.

How to Approach the Question

First, identify the key term in the question: 'confirm'. This asks for the definitive, most accurate test to establish a diagnosis.
Next, evaluate each option's primary purpose in a clinical context. Is it for diagnosis, screening, or monitoring complications/severity?
Analyze the imaging options: HRCT and Chest X-ray show the effects of a disease on the lungs (e.g., pneumonia), which can be caused by many pathogens. Therefore, they are not specific enough for confirmation.
Analyze the blood marker: D-Dimer measures a secondary process (clotting), which is a complication, not a direct measure of the virus.
Identify RT-PCR as a molecular test that directly detects the causative agent's genetic material (viral RNA). A test that finds the pathogen itself is the confirmatory test.

Concept Tested & Keywords

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