key: cord-0900925-mw74xlfg authors: Ooi, M.W.X.; Liong, S.Y.; Baguley, N.; Sharman, A.; Tuck, J. title: Role of complementary Ct chest in patients presenting with acute abdominal symptoms during covid-19 pandemic: a UK experience date: 2020-10-06 journal: Clin Imaging DOI: 10.1016/j.clinimag.2020.09.009 sha: f692b5f61113014480f2a57a51335c5b19cfd394 doc_id: 900925 cord_uid: mw74xlfg BACKGROUND: In March 2020, the UK Intercollegiate General Surgery Guidance on COVID-19 recommended that patients undergoing emergency abdominal CT should have a complementary CT chest for COVID-19 screening. PURPOSE: To establish if complementary CT chest was performed as recommended, and if CT chest influenced surgical intervention decision. To assess detection rate of COVID-19 on CT and its correlation with RT-PCR swab results. To determine if COVID-19 changes is reliably detected within the lung bases which are usually imaged in standard abdominal CT. METHODS: Patients with acute abdominal symptoms presenting to a single institution between 1st and 30th April 2020 who had abdominal CT and complementary CT chest were retrospectively extracted from Computerised Radiology Information System. CT COVID-19 changes were categorised according to British Society of Thoracic Radiology reporting guidance. Patient demographics (age and gender), RT-PCR swab results and management pathway (conservative or intervention) were recorded from electronic patient records. Statistical analyses were performed to evaluate any significant association between variables. p values ≤0.05 were regarded as statistically significant. RESULTS: Compliancy rate in performing complementary CT chest was 92.5% (148/160). Thirty-five patients (35/148,23.6%) underwent intervention during admission. There was no significant association (p = 0.9085) between acquisition of CT chest and management pathway (conservative vs intervention). CT chest had 57% sensitivity (CI 18.41% to 90.1%) and 100% specificity (CI 92% to 100%) in COVID-19 diagnosis. Three of ten patients who had classic COVID-19 changes on CT chest did not have corresponding changes in lung bases. CONCLUSION: Compliance with performing complementary CT chest in acute abdomen patients for COVID-19 screening was high and it did not influence subsequent surgical or interventional management. (conservative or intervention) were recorded from electronic patient records. Statistical analyses were performed to evaluate any significant association between variables. p values ≤0.05 were regarded as statistically significant. Compliancy rate in performing complementary CT chest was 92.5% (148/160). Thirty-five patients (35/148,23.6%) underwent intervention during admission. There was no significant association (p=0.9085) between acquisition of CT chest and management pathway (conservative vs intervention). CT chest had 57% sensitivity (CI 18.41% to 90.1%) and 100% specificity (CI 92% to 100%) in COVID-19 diagnosis. Three of ten patients who had classic COVID-19 changes on CT chest did not have corresponding changes in lung bases. Compliance with performing complementary CT chest in acute abdomen patients for COVID-19 screening was high and it did not influence subsequent surgical or interventional management. Colleges issued statements recommending the use of pre-operative chest CT to exclude asymptomatic COVID-19 in both acute and elective cases [1, 2, 3] . It recommended that patients undergoing an abdominal CT scan for acute pain as an emergency presentation should have a CT chest at the same time, unless a CT chest had previously been performed within 24 hours [1] . This guidance was adopted by our institution in April 2020. In May 2020, the RCR has published revised guidance stating that routine preoperative chest CT to screen for COVID-19 is no longer indicated and advises against a preoperative CT chest unless a positive scan would postpone the operation [4] . Although the latest RCR guidance applies only to elective pre-operative scans, as we progress into this pandemic, we should consider applying the same principles for emergency abdominal CT scans due to the low sensitivity rate of CT in diagnosing COVID-19 and emergence of rapid COVID-19 tests to keep radiation dose to a minimum. We performed a retrospective audit of all emergency CT Body examinations performed for patients presenting with acute abdomen between 1 st and 30 th April 2020 to our institution. The main aim of this audit is to establish: -if CT chest was performed in these patients as per Intercollegiate Guidance. -if the complementary CT chest findings influenced surgical intervention decision. -the detection rate of COVID-19 on CT and its correlation with COVID-19 RT-PCR swab results. -if the presence of COVID-19 changes can be reliably detected within lung bases which would normally be included in standard CT abdomen and pelvis examinations. This project was approved by local institution as a service evaluation audit and informed consent was waived. changes were classed as "classic or likely COVID-19 changes", "normal lungs", "indeterminate changes for COVID-19" and "alternate diagnoses" according to guidance issued by British Society of Thoracic Radiology (BSTI) [5] . In cases with potential discordance, simultaneous reading was held and joint consensus was achieved with a chest radiologist arbiter. Presence or absence of COVID-19 changes in the lung bases which would ordinarily have been included in a standard CT abdomen and pelvis was also separately recorded. Patient demographics (age and gender) and RT-PCR swab results for COVID-19 were obtained from electronic patient records (EPR). Clinical notes were reviewed to determine if patients were conservatively managed or underwent some form of intervention (defined as surgery or radiological intervention). The types of intervention were also recorded. Statistical analyses were performed using t-test and chi-square test for categorical variables. p values ≤0.05 were regarded as statistically significant. J o u r n a l P r e -p r o o f One hundred and sixty (n=160) CT abdomen and pelvis examinations were performed between 1 st to 30 th April 2020. Of these, twelve were excluded from analysis (ten trauma cases, one abandoned examination and one repeat examination within 48 hours). One hundred and forty-eight (n=148) were included for analysis (Fig 1) . Of these, 8% (12/148) did not have complementary CT chest. This translates to 92% (136/148) compliancy rate with the Intercollegiate guidance requiring patients to have CT chest within 24 hours of the CT abdomen and pelvis. There was no statistically significant difference in patient age nor gender between patients who had complementary CT chest and those who did not (Table 1) . Thirty-five patients (23.6%, 35/148) had some form of intervention during admission. These included three patients who did not have complementary chest CT but proceeded to have intervention (one had appendicectomy, one had an omental biopsy and one had nephrostomy tube change). There was no significant association (p=.9085) between acquisition of complementary CT chest and patient management pathway (conservative vs intervention). There was no J o u r n a l P r e -p r o o f significant difference in age (p=.8007) nor gender (p=.1422) between these two groups of patients (Table 2) . Of the patients who had complementary CT chest (n=136), ten ( Of the 10 patients with classic COVID-10 CT appearance, seven cases had these changes affecting lung bases. Our compliancy rate in performing complementary CT chest in patients who presented with acute abdomen was 92% in April 2020. Our results have shown that there is no significant association between acquisition of complementary CT chest and patient management pathway in terms of intervention vs conservative. This was also reported by Chetan, et al. [6] there remains a financial impact on the NHS in performing these additional CT examinations. According to the tariffs provided by our institution, the reimbursed cost for a CT abdomen and pelvis was £122 and the cost of a CT thorax abdomen and pelvis was £137, a net additional cost of £15. Note that this does not include any radiologist interpretation cost. Without any significant benefit from obtaining a complementary CT thorax in the management of an acute abdomen patient, the above additional expense could have been avoided. Our results show that CT had high specificity (100%) and accuracy (94%) but only moderate sensitivity (57%) for the diagnosis of COVID-19 using RT-PCR swab results as reference standard. This is similar to sensitivity rate of 61% reported in literature [7, 8] . However, confidence interval values were limited by the small sample size. In addition, there J o u r n a l P r e -p r o o f Journal Pre-proof have been reports of low sensitivity of RT-PCR swabs [9, 10] . The lung bases are routinely included in CT abdomen and pelvis examinations. However, our study suggests that the lung bases are spared in 30% (three in ten) patients with classic COVID-19 changes on CT. In April, there was report of unpublished studies suggesting that COVID-19 pulmonary changes are visible in the lung bases and this may obviate requirement to undertake additional CT chest for screening (2) . However, our findings did not support this suggestion. We note that this is a retrospective study reliant on documentation on EPR. The sample size is not large and only considers data in April 2020, which is the only data available to date as this guidance was only put into place on 30 th March 2020 in our institution. Despite the use of standardized reporting guidance from BSTI, there remains intra-observer and interobserver variability in reporting COVID-19 changes on CT. However, with a mix of subspecialty between readers, which we believe is more representative of general and acute radiology practice, the results should still be reproducible. Compliance with initial Intercollegiate Surgical Guidelines for complementary CT chest in patients presenting with acute abdominal pain was high. However, the acquisition of complementary CT chest in patients presenting with acute abdomen did not influence subsequent management such as surgical or other intervention. -CT chest had moderate sensitivity (57%) in diagnosis of COVID-19 in this patient cohort. -COVID-19 changes were not consistently seen within lung bases normally included on a standard abdominal CT. -Our institution has stopped performing complementary CT chest with emergency CT abdomen and pelvis. J o u r n a l P r e -p r o o f Intercollegiate General Surgery Guidance on COVID-19 UPDATE | The Royal College of J o u r n a l P r e -p r o o f Journal Pre-proof Surgeons of Edinburgh. The Royal College of Surgeons of Edinburgh Statement on use of CT chest to screen for COVID-19 in pre-operative patients | The Royal College of Radiologists. Rcr.ac The role of CT chest in patients presenting acutely and requiring an abdominal CT | The Royal College of Radiologists. Rcr.ac The role of CT in screening elective pre-operative patients | The Royal College of Radiologists. Rcr.ac COVID-19 Version 2 13.04.2020. Bsti.org.uk Chest CT screening for COVID-19 in elective and emergency surgical patients: experience from a UK tertiary centre CT on the Diamond Princess: What Might This Tell Us About Sensitivity for COVID-19? Chest CT Findings in Cases from the Cruise Ship "Diamond Princess Correlation of Chest CT and RT-PCR Testing in Coronavirus Disease 2019 (COVID-19) in China: A Report of 1014 Cases Evaluating the accuracy of different respiratory specimens in the laboratory diagnosis and monitoring the viral shedding of 2019-nCoV infections This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.