The role of CT Thorax as a screening tool in Covid-19 before elective urological surgeries: a tertiary care centre experience

Abstract

Background: CT thorax has been advocated and widely applied in Covid-19 clinical management. Aims and objectives: We evaluated the diagnostic value of CT thorax as a screening tool for Covid-19 in asymptomatic patients posted for elective urological surgeries & compared it with RT-PCR findings. Material & Methods: The present retrospective, observational study was conducted among those who were planned for urological surgeries in the department of Urology from April 2019 to March 2021 in a tertiary care centre institute. For each patient, a nasopharyngeal and/or oropharyngeal swab was taken and tested for the presence of SARS‑CoV‑2. If the first RT-PCR was negative, a second RT-PCR was performed within 48 hours after the first test in patients who were still admitted to the hospital. The detection rate of COVID-19 infection based on initial CT thorax & RT-PCR (as reference standard) was compared. Results: There were 24 true positive, 243 true negative, 7 false positive and 8 false negative patients. Sensitivity was 75% (95% CI: 56.60% – 88.54%), specificity: 97.20% (95% CI: 94.32 – 98.87%, positive predictive value: 61.65% (95% CI: 61.65 – 87.97%), negative predictive value: 96.81% (95% CI: 94.34 – 98.23%) and accuracy: 94.68% (95% CI: 91.38 – 96.99%). Conclusions: High diagnostic accuracy of CT with typical & relatively atypical CT findings of COVID‑19 leads to a low rate of missed diagnosis. Normal CT can be found in RT‑PCR +ve COVID‑19 cases & typical CT manifestations can be seen in RT‑PCR -ve cases. Thus, a combination of both CT & RT‑PCR may help in improving the diagnostic accuracy of Covid-19.