ABSTRACT
Since COVID-19 has spread worldwide, the role of imaging for early detection of the disease has become more prominent. Abdominal symptoms in COVID-19 are common in addition to respiratory manifestations. This review collected the available data about abdominal computed tomography (CT) and ultrasonography indications in hollow abdominal organs in patients with COVID-19 and their findings. Since abdominal imaging is less frequently used in COVID-19, there is limited information about the gastrointestinal findings. The most common indications for abdominal CT in patients with COVID-19 were abdominal pain and sepsis. Bowel wall thickening and fluid-filled colon were the most common findings in abdominal imaging. Acute mesenteric ischemia (AMI) was one of the COVID-19 presentations secondary to coagulation dysfunction. AMI manifests with sudden abdominal pain associated with high morbidity and mortality in admitted patients; therefore, CT angiography should be considered for early diagnosis of AMI. Ultrasonography is a practical modality because of its availability, safety, rapidity, and ability to be used at the bedside. Clinicians and radiologists should be alert to indications and findings of abdominal imaging modalities in COVID-19 to diagnose the disease and its potentially serious complications promptly.
ABSTRACT
[...]although solid abdominal organs are rarely affected by COVID-19, clinicians must be familiar with the manifestations since they are associated with the disease severity and poor outcome. Keywords: COVID-19, Abdominal, Imaging, Computed tomography, Ultrasonography Introduction The world has been confronting the upsurge of coronavirus disease 2019 (COVID-19) since the first novel coronavirus infection (SARS-CoV-2) initially emerged in China in December 2019.1 The most common symptoms reported in COVID-19 are related to respiratory system involvement, including fever, dry cough, fatigue, and dyspnea.2 Angiotensin-converting enzyme 2 (ACE2) plays a significant role in mediating the inflammation of COVID-19, which can contribute to COVID-19 manifestations.3 ACE2 receptors are found in various cells, including hepatocytes, cholangiocytes, podocytes, and enterocytes.2,3 Forty percent of infected patients have shown gastrointestinal (GI) manifestations, including loss of taste, nausea, vomiting, diarrhea, and abdominal pain.4 A significant number of patients have GI symptoms, and sometimes it is the only presentation of the disease without respiratory manifestations.2 The reverse-transcriptase polymerase-chain-reaction (RT-PCR) diagnostic test and chest computed tomography (CT) were reported to be highly sensitive in the early diagnostic stage of suspected COVID-19.5 Cross-sectional abdominal imaging is not usually used in COVID-19.6 Nevertheless, abdominal CT may be performed if specific symptoms exist, such as abdominal pain. Radzina et al found that multiparametric ultrasonography may be more sensitive than CT and Magnetic resonance imaging in assessing liver damage at the cellular level in patients with COVID-19 before progressing into liver cirrhosis.37 Pancreas Given the fact that ACE2 receptors are vastly expressed in pancreatic islet cells, COVID-19 can induce islet cell damage presenting with acute diabetes.38 The pancreatic involvement can occur through the direct invasion by SARS-CoV2, a systemic response to pneumonia, or a destructive immune reaction due to viral stimulation.19 According to Wang and colleagues, the pancreas was affected in 17% of patients with COVID-19 pneumonia.19 In reported cases of SARS-CoV-2 infection, abdominal CT revealed features of acute pancreatitis, including edema and inflammation of the pancreas with surrounding fluid collections and fat stranding30-39 (Figure 3). Kidney According to Pei et al, the most prevalent renal abnormalities in the setting of COVID-19 were proteinuria and hematuria, with acute kidney injury (AKI) happening less often.50 Renal infarct might occur because of hypercoagulation.6 The possible mechanisms of AKI in COVID-19 might be related to a variety of factors, including cytokine release syndrome, hypoxia, endotoxin produced by superimposed infections during ICU admission, and rhabdomyolysis.51 Different studies have established that AKI considerably increased the mortality rate in admitted patients with COVID-19.20 Renal parenchymal hypodensity and perirenal fat stranding on non-enhancement CT in patients with COVID-19 represent severe renal impairment.52 Like the spleen, the most common renal finding in abdominal tomograms was infarction.12 In such conditions, the affected kidney presents with patchy, sharply demarcated heterogeneous areas with hypoenhancement.6 A summary of renal imaging findings is shown in Table 6.