Computed tomography (CT) is widely used in diagnosing acute mesenteric ischemia (AMI), but robust identification of distinctive subtypes and stages of progression is lacking. Systematic literature search in PubMed, Cochrane Library, Web of Science and Scopus was conducted in May 2024. Studies including at least 10 adult patients and reporting radiological diagnosis of AMI versus no AMI or transmural ischemia versus no transmural ischemia were included. Meta-analyses on sensitivity and specificity of different radiological features in diagnosing AMI were conducted. From 2628 titles, 490 studies underwent full text review, and 81 were included in 14 meta-analyses. Diagnostic accuracy of CT angiography (CTA) was high - sensitivity of 92.0% and specificity of 98.8% (I2 45% and 79%, respectively), but lower for other CT protocols (sensitivity 75.8 and specificity 90.5; I2 83%). In most included studies, distinction of subtypes and severity of AMI (non-transmural or transmural) was not possible. Amongst the non-vascular features, absent/reduced bowel wall enhancement provided the best prognostic value (sensitivity 57.9 and specificity 90.1). CTA is the method of choice for diagnosing AMI with high diagnostic accuracy. None of the non-vascular features alone is sufficiently reliable to diagnose AMI or its progression to transmural necrosis, whereas a combination of different radiological features conveys a potential.

Acute mesenteric ischemia (AMI) is associated with high mortality rates. There are multiple challenges to establishing an accurate early diagnosis and providing state-of-the-art care for AMI patients. A high index of suspicion is key for early diagnosis. Once suspicion is raised, a triphasic computed tomography angiography is the essential diagnostic tool. Avoiding delays, using hybrid operating rooms and contemporary revascularization techniques for arterial occlusive AMI, can significantly improve the prognosis. Regional health care systems should be developed to direct AMI patients into centers with sufficient capabilities for providing all aspects of care at all hours. The acute care surgeon has a central role in performing laparotomies and bowel resections when needed and coordinating the management flow in close collaboration with vascular surgeons and interventional radiologists for prompt and effective revascularization. A significant share of patients with an arterial occlusive AMI can be managed by endovascular revascularization without the need for a laparotomy. There are no reliable tools for predicting transmural bowel necrosis, and individual assessment and clinical experience are very important in decision-making when choosing between laparotomy and close observation. During laparotomy, an atherosclerotic occlusion at the root of the superior mesenteric artery can be stented by using a retrograde open mesenteric or percutaneous approach, and surgical bypass is seldom needed. Using hospital-specific management pathways is very useful for the standardization of care in arterial occlusive AMI. In venous AMI, systemic anticoagulation is sufficient in most cases. In patients whose symptoms do not resolve, there are various options for endovascular and surgical revascularization. In nonocclusive mesenteric ischemia, prevention by maintaining sufficient abdominal perfusion pressure is key. High-level evidence is scarce, but with current knowledge, the prognosis of AMI patients has plenty of room for improvement.

Superior mesenteric venous thrombosis (SMVT) is mostly treated with anticoagulation therapy; however, SMVT can lead to irreversible bowel ischemia and require bowel resection in the acute or subacute phase.

We report four cases of SMVT that required careful observation and bowel resection. Case 1: A 71-year-old man presented with abdominal pain, diarrhea, and vomiting that showed a completely occluded SMV with thrombus and small bowel ischemia. Case 2: A 47-year-old man presented with abdominal pain, peritoneal irritation symptoms, and a completely occluded SMV with thrombus, ischemia of the small bowel, and massive ascites. Case 3: A 68-year-old man presented with abdominal pain and vomiting for several days and showed a partially occluded SMV with a thrombus, bowel ischemia, and massive ascites. Case 4: A 68-year-old man presented with acute abdominal pain and a partially occluded SMV with thrombus and bowel edema without ischemic changes. Anticoagulation therapy was administered; however, 3 days later, abdominal pain and bowel ischemia worsened. Bowel resection was performed in all cases.

Most idiopathic SMVT cases can be treated with anticoagulation therapy or endovascular thrombectomy. However, in cases with peritoneal irritation signs, these treatments may be ineffective, and bowel resection may be required.

Radiologists play a central role in the diagnostic and prognostic evaluation of patients with acute mesenteric ischaemia (AMI). Unfortunately, more than half of AMI patients undergo imaging with no prior suspicion of AMI, making identifying this disease even more difficult. A confirmed diagnosis of AMI is ideally made with dynamic contrast-enhanced CT but the diagnosis may be made on portal-venous phase images in appropriate clinical settings. AMI is diagnosed on CT based on the identification of vascular impairment and bowel ischaemic injury with no other cause. Moreover, radiologists must evaluate the probability of bowel necrosis, which will influence the treatment options.AMI is usually separated into different entities: arterial, venous, non-occlusive and ischaemic colitis. Arterial AMI can be occlusive or stenotic, the dominant causes being atherothrombosis, embolism and isolated superior mesenteric artery (SMA) dissection. The main finding in the bowel is decreased wall enhancement, and necrosis can be suspected when dilatation >25 mm is identified. Venous AMI is related to superior mesenteric vein (SMV) thrombosis as a result of a thrombophilic state (acquired or inherited), local injury (cancer, inflammation or trauma) or underlying SMV insufficiency. The dominant features in the bowel are hypoattenuating wall thickening with submucosal oedema. Decreased enhancement of the involved bowel suggests necrosis. Non-occlusive mesenteric ischaemia (NOMI) is related to impaired SMA flow following global hypoperfusion associated with low-flow states. There are numerous findings in the bowel characterised by diffuse extension. An absence of bowel enhancement and a thin bowel wall suggest necrosis in NOMI. Finally, ischaemic colitis is a sub-entity of arterial AMI and reflects localised colon ischaemia-reperfusion injury. The main CT finding is a thickened colon wall with fat stranding, which seems to be unrelated to SMA or inferior mesenteric artery lesions. A precise identification and description of vascular lesions, bowel involvement and features associated with transmural necrosis is needed to determine patient treatment and outcome.

The aim of this systematic review and meta-analysis was to examine and assess the basic demographic characteristics and prevalence of comorbidities in acute mesenteric ischemia (AMI) and its various subtypes.

A literature search was conducted by using the databases PubMed, EMBASE, and Google Scholar (to June 1, 2022). Random-effects or fixed-effects models were selected to pool means and proportions and their corresponding 95% confidence intervals (CI), based on heterogeneity between studies. The results of meta-analyses for basic demographic characteristics and prevalence (proportions) of each specific comorbidities of acute mesenteric ischemia (AMI) and its various subtypes were described.

Ninety-nine studies were included in the meta-analysis, including 17,103 patients with AMI. Furthermore, 7941 patients with subclass diagnoses of AMI were identified, including 3,239 patients with arterial occlusive mesenteric ischemia (AOMI), 2,977 patients with nonocclusive mesenteric ischemia (NOMI), and 1,725 patients with mesenteric venous thrombosis (MVT). As a surgical emergency, AMI is associated with older patients and a high likelihood of multisystem comorbidities. Comorbidities of AMI involved multiple systemic diseases, including cardiovascular disease, endocrine and metabolic diseases, kidney diseases, digestive diseases, respiratory diseases, cerebrovascular diseases, vascular diseases, and cancer.

The basic demographic characteristics and the prevalence of comorbidities of different subtypes of AMI are different. The management of comorbidities should be an essential part of improving the prognosis of AMI patients and may contribute to precise prevention of AMI.

Transmural intestinal necrosis (TIN) is related to high mortality in patients with acute mesenteric ischemia (AMI). Radiological predictive factors of TIN in AMI remains controversial. This study aimed to identify the CT-based predictive factors of TIN in AMI.

EMBASE and PUBMED were searched for publications predicting TIN using radiological features. Quality Assessment of Diagnostic Accuracy Studies-2 was used to assess the methodological quality of individual studies. Data were presented in terms of diagnostic odds ratio (DOR), sensitivity, specificity, and 95% confidence interval (CI). The random-effects models were used for the meta-analysis.

Eleven studies including 1037 cases with AMI were considered. The meta-analysis showed that bowel wall thinning (DOR = 13.10; 95% CI: 3.71, 46.25), decreased or absent bowel wall enhancement (DOR = 5.77; 95% CI: 2.95, 11.30), bowel dilation (DOR = 3.23; 95% CI: 2.03, 5.15), pneumatosis intestinalis (DOR = 5.78; 95% CI: 2.24, 14.95), porto-mesenteric venous gas (DOR = 5.36; 95% CI: 2.14, 13.40), and arterial occlusive AMI (DOR = 2.66; 95% CI: 1.53, 4.63) were risk factors for predicting TIN. Bowel wall thinning and porto-mesenteric venous gas displayed high specificity to diagnose TIN (98%, 95%, respectively). The subgroup analysis showed that decreased or absent bowel wall enhancement (DOR = 8.23; 95% CI: 4.67, 14.51) and bowel dilation (DOR = 3.14; 95% CI: 1.55, 6.39) were predictors of TIN in venous occlusive AMI, which were not related to TIN in arterial-origin AMI.

For predicting TIN, there are specific radiological features. The radiological predictors of TIN may differ according to the various causes of AMI. Future primary studies should further evaluate the relationships between radiological signs and TIN based on different etiologies.

• Bowel wall thinning, decreased or absent bowel wall enhancement, bowel dilation, pneumatosis intestinalis, porto-mesenteric venous gas, and arterial occlusive AMI were risk factors for predicting TIN. • Decreased or absent bowel wall enhancement and bowel dilation were predictors of TIN in venous occlusive AMI, which were not related to TIN in arterial-origin AMI.

Acute mesenteric ischemia (AMI) is a severe condition associated with poor prognosis, ultimately leading to death due to multiorgan failure. Several mechanisms may lead to AMI, and non-occlusive mesenteric ischemia (NOMI) represents a particular form of AMI. NOMI is prevalent in intensive care units in critically ill patients. In NOMI management, promptness and accuracy of diagnosis are paramount to achieve decisive treatment, but the last decades have been marked by failure to improve NOMI prognosis, due to lack of tools to detect this condition. While real-life diagnostic management relies on a combination of physical examination, several biomarkers, imaging, and endoscopy to detect the possibility of several grades of NOMI, research studies only focus on a few elements at a time. In the era of artificial intelligence (AI), which can aggregate thousands of variables in complex longitudinal models, the prospect of achieving accurate diagnosis through machine-learning-based algorithms may be sought. In the following work, we bring you a state-of-the-art literature review regarding NOMI, its presentation, its mechanics, and the pitfalls of routine work-up diagnostic exams including biomarkers, imaging, and endoscopy, we raise the perspectives of new biomarker exams, and finally we discuss what AI may add to the field, after summarizing what this technique encompasses.