EVALUATION OF COMPUTED TOMOGRAPHY (CT) CHEST AS A SCREENING TOOL FOR COVID-19 IN SURGICAL PATIENTS PRESENTING TO THE ROYAL VICTORIA HOSPITAL EMERGENCY DEPARTMENT-A NORTHERN IRISH STUDY.

Editor,

Coronavirus disease (COVID-19) is an on-going pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)1. Undiagnosed COVID-19 infection can complicate peri-operative outcomes and increase transmission to staff via aerosol-generating anaesthetic procedures. In the absence of rapid reverse transcriptase-polymerase chain reaction (RT-PCR) testing, it had been recognised that CT chest could play a role in surgical emergencies where awaiting laboratory results would delay patients’ management. On 25th March 2020, the British Society of Thoracic Imaging (BSTI) and the British Society of Gastrointestinal and Abdominal Radiology (BSGAR) recommended low-dose CT chest in addition to CT abdomen and pelvis in patients presenting as a surgical emergency2.

We aimed to evaluate the use of additional CT chest in acute surgical patients presenting to the Emergency Department (ED) of the Royal Victoria Hospital, Belfast.

CT chest, abdomen and pelvis scans requested from ED where the indication was to identify acute surgical pathology were included. Chest x-ray (CXR) and CT images were obtained from Picture Archiving and Communication System (PACS) which were graded according to the BSTI guidelines; normal, indeterminate and classic/probable COVID-193. Patient outcomes were verified from Northern Ireland Electronic Care Record (NIECR).

A total of 100 patients underwent CT chest as part of the national acute abdominal imaging pathway for COVID-19 from 1st March to 2nd May 2020.

Using BSTI CT reporting proforma, no CT chest scans were reported as classic/probable COVID-19. Three were reported as indeterminate, 78 scans were normal and 19 demonstrated other pathology. Interestingly, the only positive RT-PCR case had a normal CT chest.

Of the three patients who had indeterminate findings on CT, results did not alter surgical management in any case. The first case was asymptomatic and RT-PCR negative. CT reported patchy areas of ground glass opacification (GGO). The patient was admitted to intensive care for the management of pancreatitis.

Example of indeterminate findings on CT chest with ground glass opacification within basal aspects of both lower lobes (arrows).

The second patient was asymptomatic and RT-PCR negative. CT reported dependant lower GGO, equivocal for COVID-19. The patient proceeded to emergency laparotomy for intra-abdominal perforation. CT findings had no bearing on surgical management, however influenced bed management decisions.

The third case was a symptomatic patient with cough and fever, RT-PCR negative. CT reported GGO in the right upper lobe and multifocal consolidation in both lower lobes. The patient was managed conservatively for pancreatitis.

Additional CT chest screening had no impact on acute surgical management in our study. Due to increased radiation exposure, demand on radiology services and low diagnostic yield, BSTI/BSGAR advised that additional CT chest is no longer recommended4. Fortunately, we now have improved access to point-of-care testing e.g. LumiraDx SARS-CoV-2 Ag test which provides results within 20 minutes aiding timely surgical management5.

Table 1

CXR, CT and RT-PCR results in symptomatic cohort

Symptomatic patients	Report	%	n
CXR	Normal	35	6
	Abnormal	18	3
	Not performed	47	8
CT	Normal	82	14
	Indeterminate	6	1
	Classic/probable	0	0
	Other/non COVID	12	2
RT-PCR	Negative	76	13
	Positive	6	1
	Not performed	18	3

Table 2

CXR, CT and RT-PCR results in asymptomatic cohort.

Asymptomatic	Report	%	n
CXR	Normal	41	29
	Abnormal	17	12
	Not performed	42	30
CT	Normal	75	53
	Indeterminate	2	2
	Classic/probable	0	0
	Other/non COVID	23	16
RT-PCR	Positive	0	0
	Negative	61	43
	Not performed	39	28