key: cord-277359-za2hh71g
authors: Chae, Kum Ju; Jin, Gong Yong; Lee, Chang-Seop; Lee, Heung Bum; Lee, Ju-Hyung; Kwon, Keun-Sang
title: Positive conversion of COVID-19 after two consecutive negative RT-PCR results: A role of low-dose CT
date: 2020-06-09
journal: Eur J Radiol
DOI: 10.1016/j.ejrad.2020.109122
sha: 
doc_id: 277359
cord_uid: za2hh71g

nan

, and we would like to discuss a role of low-dose CT in discharge decision based on our recent experience regarding the positive conversion of COVID-19 after two consecutive negative RT-PCR results.

Since the initial outbreak of coronavirus disease 19 in December 2019, increasing numbers of patients have recovered and been discharged. Now is the time to turn our attention not only to diagnosis and treatment, but also to prevention of reactivation. In order to discharge patients from the hospital, most guidelines include no fever for more than 3 days, improvement of symptoms, and two consecutive negative real-time polymerase chain reaction (RT-PCR) test results [2] . However, there have been reports of false-negative RT-PCR results or reconfirmed cases after discontinuation of quarantine [3, 4] , highlighting the need to reevaluate the guidelines for discharge. Also, Dou et al. [1] recently published an article describes serial CT features in discharged COVID-19 patients with positive RT-PCR re-tests, giving us a lesson that follow-up CT after discharge is essential. Accordingly, we would like to introduce a recent case from our hospital.

A 72-year-old woman was diagnosed with COVID-19 using an RT-PCR assay for the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2) via naso-and oropharyngeal swab and was admitted to our hospital. At admission (Day 9 from the initial symptom), lowdose chest CT (LDCT) revealed patchy peripheral ground-glass opacities (GGOs) in the right upper lobe. The patient had a high fever (> 38.3°) for five days after hospitalization, and followup LDCT revealed progression of the lung lesions. After treatment, the patient's fever and respiratory symptoms resolved. After 3 days without symptoms, two consecutive naso-and oropharyngeal swabs were negative for viral RNA, and opacities on chest radiographs were improving. The patient therefore met the criteria for hospital discharge (absence of fever or symptoms and two negative RT-PCR results) established by the Korea Centers for Disease J o u r n a l P r e -p r o o f Control and Prevention [5] ; however, follow-up LDCT prior to discharge revealed newly developed multifocal GGOs in the lower lobes, which led to cancelation of discharge. After an additional 6 days, repeat naso-and oropharyngeal swab testing showed positive conversion.

With continued treatment, the patient was discharged after two consecutive negative RT-PCR results and near complete resolution of her previous pneumonia without new lesions on LDCT (Figure 1) . After continued treatment, both radiologic and PCR results were negative on Days 35 and 36. The depth of shading in the squares indicates the severity of fever and C-reactive protein concentration as follows: fever was categorized as low-grade fever (37.5-38.2℃), or highgrade fever (> 38.3℃); C-reactive protein elevation was categorized as < 1, 1-4.9, 5-9.9, ≥ 10 mg/dL. Lopinavir/ritonavir and hydroxychloroquine were used as treatments. PCR = polymerase chain reaction.

Serial CT features in discharged COVID-19 patients with positive RT-PCR re-test

SARS-CoV-2 RNA more readily detected in induced sputum than in throat swabs of convalescent COVID-19 patients

Positive RT-PCR Test Results in Patients Recovered From COVID-19

Korea Center for Disease Control & Prevention, Updates on 2019 novel coronavirus: for press release