Study design, setting, and population
This retrospective study evaluated consecutive adult patients tested for COVID-19 infection who underwent abdominal pelvic CT scan in the emergency department across an academic health system from March 15 to April 15, 2020. Patients were excluded if they were not tested for COVID-19 within 24 h of the CT or the study was performed for evaluation of trauma. If a patient underwent multiple CT studies, only the initial study was evaluated. The hospital system includes 12 hospital, 5 which are tertiary and 7 of which are community based. Dates were chosen to correspond to early onset to the peak of the COVID pandemic in our region. The study was performed with approval of the institutional review board and waiver of consent.
Data variables and collection
All CT studies of the abdomen and pelvis (with contrast, without contrast, and without/with contrast) performed within the study timeframe were identified by searching the radiology information system (RIS). Demographic information (age, gender, race) and COVID-19 PCR testing status were extracted from the system electronic health record system for all patients included in the study. COVID-19 status was determined by nasal swab PCR result in the ED or during the hospital admission. All facilities used the same PCR test. The COVID-19 tests could have been acquired 24 h before or after the CT.
Radiology report analysis
Radiology reports from the abdominal pelvic CT scans were evaluated for the presence of ground glass opacities (GGO) at the lung bases, acute abdominal pathology, including a subset of inflammatory pathology. The impression of the radiology report was reviewed to characterize CT findings and when unclear, the entire report and/or images were evaluated. Evaluation of all reports and studies were performed by a single board-certified radiologist fellowship trained in body imaging with 24 years of experience (SF) blinded to clinical data outside of the radiology report.
The presence of GGO at the lung bases was considered based on report impression, and if unclear, full radiology report and/or image evaluation. If a concomitant chest CT scan was reported, only the results of the lung bases were considered. Focal consolidation reported as bacterial pneumonia or atelectasis were not considered GGO.
Intraabdominal pathology was classified as acute abdominal pathology (“abdominal pathology”) or as the absence of acute abdominal pathology (“no abdominal pathology”). A subset of patients with acute abdominal pathology were identified with inflammatory pathology in organs with previously reported high ACE2 receptor expression including bowel, pancreas, urinary bladder, and kidney. The presence or absence and type of acute abdominal pathology was considered based on report impression. Acute abdominal pathology was defined by any inflammatory, infectious or obstructing etiologies, thromboses, hemorrhage, and neoplasm that could cause acute symptoms. Chronic or asymptomatic conditions such as hepatic steatosis, post-surgical biliary dilation, cirrhosis, diverticulosis, non-obstructing stones, neoplasm, and degenerative changes in bone were not considered to be acute pathology. In cases where the impression was vague, the report was used to help clarify the impression. For the few cases where the report was non-specific or vague, the images were viewed directly by one of the radiologists (SF) to determine the presence/absence of acute abdominal pathology.
Statistical analysis
GGO, acute abdominal pathology, and inflammatory pathology in organs with high ACE2 receptor expression were compared by COVID-19 result status for all patients. Further, the presence of abdominal pathology and inflammatory pathology in organs with high ACE2 receptor expression was compared by COVID-19 and GGO for all patients and stratified by COVID and GGO findings. Statistical analyses were performed using Chi square. Statistical significance was considered for p value < 0.05. All statistical analyses were done in SAS v9.4 (SAS Institute).