The role of CT chest in screening for asymptomatic COVID-19 infection in self-isolating patients prior to elective oncological surgery: findings from a UK Cancer Hub

Abstract

Objectives: In accordance with initial guidance from the Royal College of Surgeons and Royal College of Radiologists, we evaluated the utility of CT of the chest in the exclusion of asymptomatic COVID-19 infection prior to elective cancer surgery on self-isolating patients during the pandemic.

Methods: All surgical referrals without symptoms of COVID-19 infection in April and May 2020 were included. Patient records were retrospectively reviewed. Screening included CT chest for major thoracic and abdominal surgery. CTs were reported according to British Society of Thoracic Imaging guidelines and correlated with reverse transcriptase polymerase chain reaction (RT-PCR) and surgical outcomes.

Results: The prevalence of RT-PCR confirmed COVID-19 infection in our screened population was 0.7% (5/681). 240 pre-operative CTs were performed. 3.8% (9/240) of CTs were reported as abnormal, only one of which was RT-PCR positive. 2% (5/240) of cases had surgery postponed based on CT results. All nine patients with CTs reported as abnormal have had surgery, all without complication.

Conclusion: The prevalence of asymptomatic COVID-19 infection in our screened population was low. The pre-test probability of CT chest in asymptomatic, self-isolating patients is consequently low. CT can produce false positives in this setting, introducing unnecessary delay in surgery for a small proportion of cases.

Advances in knowledge: Self-isolation, clinical assessment and RT-PCR are effective at minimising COVID-19 related surgical risk. The addition of CT chest is unhelpful. Our data have particular relevance during the second wave of infection and in the recovery phase.

Figure 1.

Images from the nine cases with “positive” CTs. The nine cases with “positive” CT results correspond to those listed in Table 4. Cases 1–3 were regarded as true-positive CT results, with areas of peripheral consolidation and/ or ground glass density, indicating either “probable COVID-19” or “classic COVID-19”. Cases 4–9 were regarded as false-positive CT results, with either very limited extent of ground glass opacity, or features more suggestive of a non-COVID-19 process (arrows).

Figure 2.

Flowchart showing the clinical impact of pre-operative CT chest on surgical outcome. RT-PCR, reverse transcriptase polymerase chain reaction