Are asymptomatic gastrointestinal findings on imaging more common in COVID-19 infection? Study to determine frequency of abdominal findings of COVID-19 infection in patients with and without abdominal symptoms and in patients with chest-only CT scans

Comparison between abdominal CT findings in intensive care unit (ICU) and non-ICU patients with Covid-19: experience from a tertiary care hospital

Background

16-66% of COVID-19 positive patients may have abdominal symptoms and findings in abdominal CT. The yield of abdominal CT scan in patients having abdominal complaints is not known.

Objectives

The aim of this study was to explore the various abdominal imaging manifestations of COVID-19 and COVID-19 associated Mucormycosis (CAM) and to identify the relevant clinical and laboratory features associated with severity of the symptoms.

Methods

A retrospective single centre observational study was performed at a tertiary care hospital in Northwest India. All consecutive patients who had COVID positive RT-PCR report and had undergone abdominal Computed Tomography scan from March 2020 to November 2021 for various abdominal complaints were included. Demographic data, CT images and reports and all relevant lab parameters were collected.

Results

Out of 75 patients, positive abdominal findings were seen in 65 patients. Hepatobiliary findings were seen in 41.3% (31 of 75; OR=1.9) and bowel abnormalities were found in 37.3% (28 of 75; OR=2.1) of COVID-19 patients. 7 patients who had renal infarcts or bowel ischemia were found to have COVID-19 associated Mucormycosis on histopathology.

Conclusion

Chest CT severity score was positively correlated with most of the abdominal manifestations in patients requiring ICU admission. Elevated D-dimer levels were significantly associated with abdominal symptoms.

Evaluation of abdominal computed tomography findings in patients with COVID-19: a multicenter study

PURPOSE

To evaluate the frequency of abdominal computed tomography (CT) findings in patients with coronavirus disease-2019 (COVID-19) and interrogate the relationship between abdominal CT findings and patient demographic features, clinical findings, and laboratory test results as well as the CT atherosclerosis score in the abdominal aorta.

METHODS

This study was designed as a multicenter retrospective study. The abdominal CT findings of 1.181 patients with positive abdominal symptoms from 26 tertiary medical centers with a positive polymerase chain-reaction test for severe acute respiratory syndrome coronavirus 2 were reviewed. The frequency of ischemic and non-ischemic CT findings as well as the association between CT findings, clinical features, and abdominal aortic calcific atherosclerosis score (AA-CAS) were recorded.

RESULTS

Ischemic and non-ischemic abdominal CT findings were detected in 240 (20.3%) and 328 (27.7%) patients, respectively. In 147 patients (12.4%), intra-abdominal malignancy was present. The most frequent ischemic abdominal CT findings were bowel wall thickening (n = 120; 10.2%) and perivascular infiltration (n = 40; 3.4%). As for non-ischemic findings, colitis (n = 91; 7.7%) and small bowel inflammation (n = 73; 6.2%) constituted the most frequent disease processes. The duration of hospital stay was found to be higher in patients with abdominal CT findings than in patients without any positive findings (13.8 ± 13 vs. 10.4 ± 12.8 days, P < 0.001). The frequency of abdominal CT findings was significantly higher in patients who did not survive the infection than in patients who were discharged after recovery (41.7% vs. 27.4%, P < 0.001). Increased AA-CAS was found to be associated with a higher risk of ischemic conditions in abdominal CT examinations.

CONCLUSION

Abdominal symptoms in patients with COVID-19 are usually associated with positive CT findings. The presence of ischemic findings on CT correlates with poor COVID-19 outcomes. A high AA-CAS is associated with abdominal ischemic findings in patients with COVID-19.

Multimodal ultrasound imaging with conventional B-mode, elastography, and parametric analysis of contrast-enhanced ultrasound (CEUS): A novel approach to assess small bowel manifestation in severe COVID-19 disease

The aim was to describe the small bowel morphology with conventional B-mode and elastography and additionally to evaluate dynamic effects of COVID-19 associated small bowel microvascularization using CEUS with color coded perfusion parameters.Thirteen patients with severe COVID-19 acute respiratory distress syndrome (ARDS) were investigated. 13 patients required intensive care treatment with mechanical ventilation. Five patients required extracorporeal membrane oxygenation (ECMO). Contrast-enhanced ultrasound (CEUS) was performed by an experienced investigator as a bolus injection of up to 2.4 ml sulfur hexafluoride microbubbles via a central venous catheter. In the parametric analysis of CEUS, the flare of microbubbles over time is visualized with colors. This is the first work using parametric analysis of CEUS to detect perfusion differences in the small bowel.Parametric analysis of CEUS in the intestinal phase was carried out, using DICOM loops for 20 seconds. In 5 patients, parametric analysis revealed intraindividual differences in contrast agent behavior in the small bowel region. Analogous to the computed tomography (CT) images parametric analysis showed regions of simultaneous hyper- and hypoperfusion of the small intestine in a subgroup of patients. In 5 patients, the parametric image of transmural global contrast enhancement was visualized.Our results using CEUS to investigate small bowel affection in COVID-19 suggest that in severe COVID-19 ARDS systemic inflammation and concomitant micro embolisms may lead to disruption of the epithelial barrier of the small intestine.This is the first study using parametric analysis of CEUS to evaluate the extent of small bowel involvement in severe COVID-19 disease and to detect microemboli. In summary, we show that in COVID-19 the small bowel may also be an important interaction site. This is in line with the fact that enterocytes have been shown to a plenitude of angiotensin converting enzyme (ACE)-2 receptors as entry sites of the virus.

Abdominal Imaging Findings in Patients with COVID-19 Part 2: Solid Organs

Since severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) first appeared in China in December 2019, the globe has been dealing with an ever-increasing incidence of coronavirus disease 2019 (COVID-19). In addition to respiratory disorders, 40% of patients present with gastrointestinal (GI) involvement. Abdominal pain is the most common indication for computed tomography (CT) and ultrasonography. After GI tract involvement, solid visceral organ infarction is the most prevalent abdominal abnormality in COVID-19. This review aims to gather the available data in the literature about imaging features of solid abdominal organs in patients with COVID-19. Gallbladder wall thickening and distension, cholelithiasis, hyperdense biliary sludge, acalculous cholecystitis, periportal edema, heterogeneous liver enhancement, and liver hypodensity and infarction are among hepatobiliary imaging findings in CT, particularly in patients admitted to ICU. Pancreatic involvement can develop as a result of direct SARS-CoV2 invasion with signs of acute pancreatitis in abdominal CT, such as edema and inflammation of the pancreas. Infarction was the most prevalent renal and splenic involvement in patients with COVID-19 who underwent abdominal CT presenting with areas of parenchymal hypodensity. In conclusion, 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.

Findings of Abdominal Imaging in Patients with COVID-19 - Part 1: Hollow Organs

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.

Multiorgan Involvement in SARS-CoV-2 Infection: The Role of the Radiologist from Head to Toe

Radiology plays a crucial role for the diagnosis and management of COVID-19 patients during the different stages of the disease, allowing for early detection of manifestations and complications of COVID-19 in the different organs. Lungs are the most common organs involved by SARS-CoV-2 and chest computed tomography (CT) represents a reliable imaging-based tool in acute, subacute, and chronic settings for diagnosis, prognosis, and management of lung disease and the evaluation of acute and chronic complications. Cardiac involvement can be evaluated by using cardiac computed tomography angiography (CCTA), considered as the best choice to solve the differential diagnosis between the most common cardiac conditions: acute coronary syndrome, myocarditis, and cardiac dysrhythmia. By using compressive ultrasound it's possible to study the peripheral arteries and veins and to exclude the deep vein thrombosis, directly linked to the onset of pulmonary embolism. Moreover, CT and especially MRI can help to evaluate the gastrointestinal involvement and assess hepatic function, pancreas involvement, and exclude causes of lymphocytopenia, thrombocytopenia, and leukopenia, typical of COVID-19 patients. Finally, radiology plays a crucial role in the early identification of renal damage in COVID-19 patients, by using both CT and US. This narrative review aims to provide a comprehensive radiological analysis of commonly involved organs in patients with COVID-19 disease.

Mesenteric ischemia in patients with COVID-19: an updated systematic review of abdominal CT findings in 75 patients

Background

Acute mesenteric ischemia (AMI) is a less common but devastating complication of COVID-19 disease. The aim of this systematic review was to assess the most common CT imaging features of AMI in COVID-19 and also provide an updated review of the literature on symptoms, treatment, histopathological and operative findings, and follow-up of these patients.

Methods

A systematic literature search of four databases: Pubmed, EMBASE, WHO database, and Google Scholar, was performed to identify all the articles which described abdominal CT imaging findings of AMI in COVID-19.

Results

A total of 47 studies comprising 75 patients were included in the final review. Small bowel ischemia (46.67%) was the most prevalent abdominal CT finding, followed by ischemic colitis (37.3%). Non-occlusive mesenteric ischemia (NOMI; 67.9%) indicating microvascular involvement was the most common pattern of bowel involvement. Bowel wall thickening/edema (50.9%) was more common than bowel hypoperfusion (20.7%). While ileum and colon both were equally involved bowel segments (32.07% each), SMA (24.9%), SMV (14.3%), and the spleen (12.5%) were the most commonly involved artery, vein, and solid organ, respectively. 50% of the patients receiving conservative/medical management died, highlighting high mortality without surgery. Findings on laparotomy and histopathology corroborated strikingly with CT imaging findings.

Conclusion

In COVID-19 patients with AMI, small bowel ischemia is the most prevalent imaging diagnosis and NOMI is the most common pattern of bowel involvement. Contrast-enhanced CT is a powerful decision-making tool for prompt diagnosis of AMI in COVID-19, thereby potentially improving time to treat as well as clinical outcomes.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s00261-021-03337-9.

Contrast enhanced ultrasonography (CEUS) a novel tool to detect intestinal epithelial barrier dysfunction in severe COVID-19 disease

Ten patients with confirmed COVID-19 disease were studied. Nine patients required intensive care treatment, among them four needed extracorporeal membrane oxygenation (ECMO). Contrast enhanced ultrasonography (CEUS) was performed by one experienced investigator as a bolus injection of up to 2.4 ml of sulphur hexafluoride microbubbles via a central venous catheter. B-Mode evaluation and strain elastography showed mural edema of the small bowel with a thickness of up to 10 mm in all patients. We applied color coded Doppler sonography (CCDS) and power mode with flow-adapted parameters and early, dynamic capillary arterial contrast enhancement of bowel wall structures <10 s to assess perfusion of the small bowel. In all patients, reactive hyperemia was seen in the entire small bowel. In a subgroup of seven patients microbubbles translocated into the intestinal lumen. Thus, high-grade intestinal barrier disruption secondary to SARSCoV-2 infection can be postulated in these patients. This is the first description of perfusion changes and a disruption of the small bowel epithelial barrier in COVID-19 Patients using contrast ultrasonography and elastography.

The demographic, clinical, and medical manifestations of pulmonary thromboembolism development in COVID-19

Background

Since the emergence of coronavirus disease 2019 (COVID-19), various clinical manifestations ranging from asymptomatic to severe, life-threatening courses have been presented. It is well known that COVID-19 patients are at an increased risk of pulmonary thromboembolism (PTE) development; however, the associated demographic, medical, and clinical factors for developing PTE remain unknown. The current study aimed to assess the characteristics of patients with PTE.

Methods

This case-control study was derived from an ongoing population-based investigation of hospitalized patients with COVID-19 pneumonia. The case group included 99 patients with PTE confirmed by computed tomography pulmonary angiography (CTPA), and the controls (N=132) were age-matched patients selected from the PTE-suspected patients with a negative CTPA. The demographic, medical, and clinical characteristics of the study population were entered into the study checklist and compared. A logistic regression test was used to determine the factors associated with PTE development.

Results

Among the 13,099 admitted patients, 690 (5.26%) were suspected of having PTE according to their clinical manifestations. CTPA was performed for suspected cases, and PTE was confirmed in 132 patients (19.13%). Logistic regression assessments revealed that male gender (OR, 2.39; 95%CI, 1.38‒4.13), decreased oxygen saturation (OR, 2.33; 95%CI, 1.27‒4.26), and lower hemoglobin (OR, 0.83, 0.95), and albumin (OR, 0.31; 95%CI, 0.18‒0.53) levels were associated with PTE development.

Conclusion

PTE was confirmed in one-fifth of suspected patients who underwent CTPA imaging. Male sex, decreased oxygen saturation, and lower levels of hemoglobin and albumin were independent predictors of PTE in patients with COVID-19 pneumonia.

Abdominal Computed Tomography Imaging Findings in Hospitalized COVID-19 Patients: A Year-Long Experience and Associations Revealed by Explainable Artificial Intelligence

The aim of this retrospective study is to assess any association between abdominal CT findings and the radiological stage of COVID-19 pneumonia, pulmonary embolism and patient outcomes. We included 158 adult hospitalized COVID-19 patients between 1 March 2020 and 1 March 2021 who underwent 206 abdominal CTs. Two radiologists reviewed all CT images. Pathological findings were classified as acute or not. A subset of patients with inflammatory pathology in ACE2 organs (bowel, biliary tract, pancreas, urinary system) was identified. The radiological stage of COVID pneumonia, pulmonary embolism, overall days of hospitalization, ICU admission and outcome were registered. Univariate statistical analysis coupled with explainable artificial intelligence (AI) techniques were used to discover associations between variables. The most frequent acute findings were bowel abnormalities (n = 58), abdominal fluid (n = 42), hematomas (n = 28) and acute urologic conditions (n = 8). According to univariate statistical analysis, pneumonia stage > 2 was significantly associated with increased frequency of hematomas, active bleeding and fluid-filled colon. The presence of at least one hepatobiliary finding was associated with all the COVID-19 stages > 0. Free abdominal fluid, acute pathologies in ACE2 organs and fluid-filled colon were associated with ICU admission; free fluid also presented poor patient outcomes. Hematomas and active bleeding with at least a progressive stage of COVID pneumonia. The explainable AI techniques find no strong relationship between variables.

The Multifaceted COVID-19: CT Aspects of Its Atypical Pulmonary and Abdominal Manifestations and Complications in Adults and Children. A Pictorial Review

Our daily experience in a COVID hospital has allowed us to learn about this disease in many of its changing and unusual aspects. Some of these uncommon manifestations, however, appeared more frequently than others, giving shape to a multifaceted COVID-19 disease. This pictorial review has the aim to describe the radiological aspects of atypical presentations and of some complications of COVID-19 disease in adults and children and provide a simple guide for radiologists to become familiar with the multiform aspects of this disease.

A Systematic Review of Abdominal Imaging Findings in COVID-19 Patients

OBJECTIVE

The objective of this systematic review was to evaluate key imaging manifestations of COVID-19 on abdominal imaging by utilizing a comprehensive review of the published literature.

METHOD

A systematic literature search from PubMed, Google Scholar, and Scopus was performed for studies mentioning abdominal imaging findings in COVID-19 patients. Studies published from inception to 15 March 2021 were included.

RESULTS

A total of 116 studies comprising 1,198 patients were included. Abdominal pain was the most common indication for abdominal imaging in 50.2% of the patients. No abnormality was seen in 48.1% of abdominopelvic computed tomography scans. Segmental bowel wall thickening (14.7%) was the most common imaging abnormality, followed by bowel ischemia (7.1%), solid organ infarction (6.7%), vessel thrombosis (6.7%), and fluid-filled colon (6.2%). Other relevant findings were dilated air-filled bowel, pancreatitis, pneumatosis/portal venous gas, bowel perforation, and appendicitis. Other than abdominal findings, COVID-19-related basal lung changes were incidentally detected in many studies. Moreover, the presence of bowel imaging findings was positively correlated with the clinical severity of COVID-19 infection.

CONCLUSION

This review describes the abdominal imaging findings in COVID-19 patients. This is pertinent for the early diagnosis of COVID-19 in patients presenting solely with abdominal symptoms as well as in identifying abdominal complications in a known case of COVID-19.

Acute mesenteric ischemia and small bowel imaging findings in COVID-19: A comprehensive review of the literature

BACKGROUND

Coronavirus disease 2019 (COVID-19), an infectious condition caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has rapidly spread worldwide since its first description in Wuhan in December 2019. Even though respiratory manifestations are the most prevalent and responsible for disease morbidity and mortality, extrapulmonary involvement has progressively gained relevance. In particular, gastrointestinal (GI) signs and symptoms, reported in up to two-thirds of patients with COVID-19, might represent the first and, in some cases, the only disease presentation. Their presence has been associated in some studies with an increased risk of a severe disease course. Proposed pathogenic mechanisms explaining GI tract involvement are either direct viral access to intestinal cells via angiotensin-converting enzyme 2 or indirect damage of the intestinal wall through mesenteric ischemia induced by the hypercoagulable state associated with COVID-19 infection. Although not typical of SARS-CoV-2 infection, several small bowel manifestations have been described in infected patients who underwent any form of abdominal imaging. The radiological findings were mainly reported in patients with abdominal symptoms, among which abdominal pain was the most common.

AIM

To discuss small bowel radiological manifestations of SARS-CoV-2 infection in abdominal imaging studies.

METHODS

Bibliographical searches were performed in PubMed, using the following keywords: “COVID-19” AND “imaging” AND “gastrointestinal” OR “abdominal” OR “small bowel”.

RESULTS

Of 62 patients with described radiologic small bowel alterations, mesenteric ischemia was diagnosed in 31 cases (50%), small bowel wall thickening in 10 cases (16%), pneumatosis in nine cases (15%), intussusception in eight cases (13%), pneumoperitoneum in two cases (3%) and paralytic ileus in two cases (3%). We also reported mesenteric adipose tissue hypertrophy and lymph nodes enlargement in a young woman.

CONCLUSION

So far it is difficult to establish whether these manifestations are the direct consequence of SARS-CoV-2 infection or collateral findings in infected patients, but their recognition would be pivotal to set a closer follow-up and to reduce missed diagnoses.

Abdominal and gastrointestinal manifestations in COVID-19 patients: Is imaging useful?

Coronavirus disease 2019 (COVID-19) can be considered a systemic disease with a specific tropism for the vascular system, in which the alterations of the microcirculation have an important pathogenetic role. The lungs are the main organ involved in COVID-19, and severe progressive respiratory failure is the leading cause of death in the affected patients; however, many other organs can be involved with variable clinical manifestations. Concerning abdominal manifestations, the gastrointestinal tract and the hepatobiliary system are mainly affected, although the pancreas, urinary tract and spleen may also be involved. The most common gastrointestinal symptoms are loss of appetite, followed by nausea and vomiting, diarrhea and abdominal pain. Gastrointestinal imaging findings include bowel wall thickening, sometimes associated with hyperemia and mesenteric thickening, fluid-filled segments of the large bowel and rarely intestinal pneumatosis and ischemia. Hepatic involvement manifests as an increase in the enzymatic levels of alanine aminotransferase, aspartate aminotransferase, serum bilirubin and γ-glutamyl transferase with clinical manifestations in most cases mild and transient. The most frequent radiological features are hepatic steatosis, biliary sludge and gallstones. Edematous acute pancreatitis, kidney infarct and acute kidney injury from acute tubular necrosis have been described more rarely in COVID-19. Lastly, splenic involvement is characterized by splenomegaly and by the development of solitary or multifocal splenic infarcts with classic wedge-shaped or even rounded morphology, with irregular or smooth profiles. In summary, the abdominal radiological findings of COVID-19 are nonspecific and with poor pathological correlation reported in the literature. Ultrasound and particularly computed tomography with multiphasic acquisition are the diagnostic methods mainly utilized in COVID-19 patients with abdominal clinical symptoms and signs. Although radiological signs are not specific of abdominal and gastrointestinal involvement, the diagnostic imaging modalities and in particular computed tomography are helpful for the clinician in the management, evaluation of the severity and evolution of the COVID-19 patients.

Pathophysiology of infection with SARS-CoV-2-What is known and what remains a mystery

Coronavirus disease 2019 (COVID‐19), caused by coronavirus severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), has caused extensive disruption and mortality since its recent emergence. Concomitantly, there has been a race to understand the virus and its pathophysiology. The clinical manifestations of COVID‐19 are manifold and not restricted to the respiratory tract. Extrapulmonary manifestations involving the gastrointestinal tract, hepatobiliary system, cardiovascular and renal systems have been widely reported. However, the pathophysiology of many of these manifestations is controversial with questionable support for direct viral invasion and an abundance of alternative explanations such as pre‐existing medical conditions and critical illness. Prior research on SARS‐Co‐V and NL63 was rapidly leveraged to identify angiotensin‐converting enzyme 2 (ACE2) receptor as the key cell surface receptor for SARS‐CoV‐2. The distribution of ACE2 has been used as a starting point for estimating vulnerability of various tissue types to SARS‐CoV‐2 infection. Sophisticated organoid and animal models have been used to demonstrate such infectivity of extrapulmonary tissues in vitro, but the clinical relevance of these findings remains uncertain. Clinical autopsy studies are typically small and inevitably biased towards patients with severe COVID‐19 and prolonged hospitalization. Technical issues such as delay between time of death and autopsy, use of inappropriate antibodies for paraffin‐embedded tissue sections and misinterpretation of cellular structures as virus particles on electron micrograph images are additional problems encountered in the extant literature. Given that SARS‐CoV‐2 is likely to circulate permanently in human populations, there is no doubt that further work is required to clarify the pathobiology of COVID‐19.