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.

A grading system was developed for computerized tomography (CT) scans evaluating patients with suspected small bowel obstruction (SBO). We hypothesized that patients with a higher grade of suspected SBO on CT scan would be more likely to require surgical intervention.

Retrospective chart review of patients who presented to the Emergency Room (ER) who had a CT of the abdomen and pelvis for suspected SBO. Patients were divided into 5 groups: Grade 1 (SBO unlikely), Grade 2 (probable partial or early SBO), Grade 3 (probable high grade SBO), Grade 4 (SBO with changes concerning for ischemia) and Not Graded.

The CT scans of 655 patients were graded. Of the 22 patients with a grade 1 SBO, only 1 went for surgery (4.5 %). For grade 2 patients, 23 out of 299 had an operation (7.7 %), for grade 3 it was 84 out of 299 (28.1 %) and for grade 4 SBO, 25 out of 35 patients (71.4 %) had surgery. The p value is <0.00001. The three most common intraoperative findings were SBO obstruction from adhesions alone (48 % of cases), followed by incarcerated hernias (12 %) and ischemic bowel (9 %). Only 8 cases out of 133 operations (6 % of total) had no findings at time of surgery other than dilated bowel.

The CT grading scale for SBO developed at our institution shows excellent correlation between grade and going for surgery, with few negative results, and can be a useful tool among other factors for general surgeons when deciding whether or not to operate on a patient with suspected SBO.

The aim of the study was to develop a prediction model for closed-loop small bowel obstruction integrating computed tomography (CT) and clinical findings.

The radiology database and surgical reports from 2 suburban teaching hospitals were retrospectively reviewed for patients undergoing surgery for suspected closed-loop small bowel obstruction (CLSBO). Two observers independently reviewed the CT scans for the presence of imaging features of CLSBO, blinded to the surgically confirmed diagnosis and clinical parameters. Random forest analysis was used to train and validate a prediction model for CLSBO, by combining CT and clinical findings, after randomly splitting the sample into 80% training and 20% test subsets.

Surgery confirmed CLSBO in 185 of 223 patients with clinically suspected CLSBO. Age greater than 52 years showed 2.82 (95% confidence interval = 1.13-4.77) times higher risk for CLSBO (P = 0.021). Sensitivity/specificity of CT findings included proximal dilatation (97/5%), distal collapse (96/2%), mesenteric edema (94/5%), pneumatosis (1/100%), free air (1/98%), and portal venous gas (0/100%). The random forest model combining imaging/clinical findings yielded an area under receiver operating curve of 0.73 (95% confidence interval = 0.58-0.94), sensitivity of 0.72 (0.55-0.85), specificity of 0.8 (0.28-0.99), and accuracy of 0.73 (0.57-0.85). Prior surgery, age, lactate, whirl sign, U/C-shaped bowel configuration, and fecalization were the most important variables in predicting CLSBO.

A random forest model found clinical factors including prior surgery, age, lactate, and imaging factors including whirl sign, fecalization, and U/C-shaped bowel configuration are helpful in improving the prediction of CLSBO. Individual CT findings in CLSBO had either high sensitivity or specificity, suggesting that accurate diagnosis requires systematic assessment of all CT signs.

To correlate CT-findings in patients with closed-loop small bowel obstruction (CL-SBO) with perioperative findings, to identify patients who require immediate surgical intervention. Secondary purpose was to substantiate the role of radiologists in predicting perioperative outcome.

Data were retrospectively obtained from patients with surgically confirmed CL-SBO, between September 2013 and September 2019. Three radiologists reviewed CTs to assess defined CT features and predict patient outcome for bowel wall ischemia and necrosis using a likelihood score. Univariate statistical analyses were performed and diagnostic performance parameters and interobserver agreement were assessed for each feature.

Of 148 included patients, 28 (19%) intraoperatively had viable bowel and 120 (81%) had bowel wall ischemia or necrosis. Most CT characteristics, as well as the likelihood of ischemia and necrosis, found fair or moderate multirater agreement. Increased attenuation of bowel wall and mesenteric vessels on non-contrast-enhanced CT had a specificity for bowel ischemia or necrosis of 100% (sensitivity respectively 48% (p < 0.001) and 21% (p = 0.09)). Mesenteric edema had high sensitivity for ischemia or necrosis (90%), but specificity of only 26% (p < 0.001). For mesenteric fluid, sensitivity was 60% and specificity 57% (p = 0.004). Decreased enhancement of bowel wall in both arterial and PV-phase showed significant correlation, respectively a sensitivity of 58% and 42%, and specificity of 88% and 79% (both p < 0.001). Likelihood of both ischemia and necrosis were significantly correlated with perioperative outcome (p < 0.001).

CT findings concerning mesenteric and bowel wall changes, as well as radiologists' judgement of likelihood of ischemia and necrosis are significantly correlated with perioperative outcome of bowel wall ischemia and necrosis in patients with CL-SBO.

Gastrointestinal tract lesions are major causes of acute abdominal pain. A rapid, accurate, and reliable diagnosis is required to manage patients. Magnetic resonance imaging (MRI) is a nonionizing modality that is beneficial for pregnant women, children, and young adults who are sensitive to ionizing radiation. For patients with renal impairment who are not accurately diagnosed with noncontrast computed tomography, noncontrast MRI can serve as an alternative diagnostic modality. MRI protocols used for acute abdominal pain are supposed to be optimized and prioritized to shorten scanning times. Single-shot T2-weighted and fat-suppressed T2-weighted imaging are important pulse sequences that are used to reveal pathology and inflammation in the gastrointestinal tract. Diffusion-weighted imaging clearly depicts inflammation and abscesses as hyperintense lesions. Most acute gastrointestinal tract lesions, including inflammation, ischemia, obstruction, and perforation, demonstrate bowel wall thickening. Bowel obstruction and adynamic ileus present bowel dilatation, and perforation and penetration show bowel wall defects. MRI can be used to reveal these pathological findings with some characteristics depending on their underlying pathophysiology. This review article discusses imaging modalities for acute abdominal pain, describes a noncontrast MRI protocol for acute abdominal pain caused by gastrointestinal tract lesions, and reviews MRI findings of acute gastrointestinal tract lesions.

Small-bowel obstruction is a common cause of abdominal pain and accounts for a significant proportion of hospital admissions. Radiologic imaging plays the key role in the diagnosis and management of small-bowel obstruction as neither patient presentation, the clinical examination, nor laboratory testing are sufficiently sensitive or specific enough to diagnose or guide management. This document focuses on the imaging evaluation of the two most commonly encountered clinical scenarios related to small-bowel obstruction: the acute presentation and the more indolent, low-grade, or intermittent presentation. This document hopes to clarify the appropriate utilization of the many imaging procedures that are available and commonly employed in these clinical settings. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

To perform a systematic review and meta-analysis evaluating the diagnostic performance of computed tomography (CT) for small bowel obstruction (SBO), including diagnostic accuracy, ischemia, predicting surgical intervention, etiology and transition point.

PubMed/MEDLINE and related databases were searched for research articles published from their inception through August 2018. Findings were pooled using bivariate random-effects and summary receiver operating characteristic curve models. Meta-regression and subgroup analyses were performed to evaluate whether publication year, patient age, enhanced CT, slice thickness and pathogenesis affected classification accuracy.

In total, 45 studies with a total of 4004 patients were included in the analysis. The pooled sensitivity and specificity of CT for SBO were 91% (95% confidence interval [CI]: 84%, 95%) and 89% (95% CI: 81%, 94%), respectively, and there were no differences in the subgroup analyses of age, publication year, enhanced CT and slice thickness. For ischemia, the pooled sensitivity and specificity was 82% (95% CI: 67%, 91%) and 92% (95% CI: 86%, 95%), respectively. No difference was found between enhanced and unenhanced CT based on subgroup analysis; however, high sensitivity was found in adhesive SBO compared with routine causes (96% vs. 78%, P = 0.03). The pooled sensitivity and specificity for predicting surgical intervention were 87% and 73%, respectively. The accuracy for etiology of adhesions, hernia and tumor was 95%, 70% and 82%, respectively. In addition, the pooled sensitivity and specificity for transition point was 92% and 77%, respectively.

CT has considerable accuracy in diagnosis of SBO, ischemia, predicting surgical intervention, etiology and transition point.

To evaluate the inter-reader agreement of the CT features of acute mesenteric ischemia (AMI).

Between 2006 and 2014, 109 patients (57 men, 52%, mean age 50 years old [17-83]) admitted to our institution with a diagnosis of AMI were included. CT scans (42% were initially performed in our institution) were reviewed by two abdominal radiologists. Inter-observer agreement of the imaging features of vascular insufficiency and bowel ischemia was assessed by the percentage of agreement and the kappa value.

The final population included, Inter-observer agreement varied according to the different features (κ = 0.25-0.98). Inter-observer agreement for decreased/absent bowel wall enhancement was moderate (κ = 0.52), but was almost perfect (κ = 0.82) in the 47 patients (43%) with both unenhanced and arterial-phase images without positive oral contrast agent and excellent CT images quality.

Inter-reader agreement was moderate to substantial for most CT features of AMI. Multiphasic CT scan protocol, including unenhanced, arterial phase and venous phase images, without positive oral contrast agent, and excellent CT images quality improve inter-observer agreement of imaging features of AMI, especially for decreased/absent bowel wall enhancement, and should be performed in patients with suspected AMI.

Small bowel obstruction is a common and significant surgical presentation. Approximately 30% of presentations will require surgery during admission. The great challenge of adhesive small bowel obstruction (ASBO) management is the early detection of silent intestinal ischaemia in patients initially deemed suitable for conservative therapy. Recent literature emphasizes the effectiveness of computed tomography enterography and water-soluble contrast studies in the management of ASBO. Low-volume undiluted water-soluble contrast has been shown to have both triage and therapeutic value in the management of ASBO. Their use has been demonstrated to reduce the need for surgery to below 20%. There has also been growing interest in clinicoradiological algorithms which aim to predict ischaemia early in the course of presentation. The aim of this review is to summarize the latest evidence and clarify previous uncertainties, specifically regarding the duration of conservative treatment, timing of contrast studies and the reliability of predictive algorithms. Based on this latest evidence, we have formulated a management protocol which aims to integrate these latest developments and formalize a strategy for best management in ASBO.

Pneumatosis intestinalis is rare but may be associated with life-threatening intra-abdominal conditions such as intestinal ischemia or perforation. However, it can be difficult, particularly in the very elderly, to identify candidates for immediate surgical intervention.

A 94-year-old man with abdominal distension underwent abdominal computed tomography, which demonstrated accumulation of air bubbles within the intestinal wall and some free intraperitoneal air, suggestive of pneumatosis intestinalis. His vital signs showed evidence of systemic inflammatory response syndrome, and laboratory examination revealed inflammation and hypoxia. As the patient was frail, with his age and concomitant conditions which may have masked the symptoms and severity of his illness, immediate diagnostic laparoscopy was performed, which confirmed the diagnosis of pneumatosis intestinalis, with multiple gas-filled cysts seen within the subserosa of the small intestine. No additional surgical procedure was performed. His symptoms improved postoperatively.

Optimal management of pneumatosis intestinalis in a timely manner requires a comprehensive evaluation of factors in each individual. In patients with severe symptoms, PI might be a sign of a life-threatening intra-abdominal emergency. Despite the contrast-enhanced CT and prediction markers in previous reports, it considered to be difficult to completely rule out these fatal conditions without surgery, especially in very elderly patients with poor performance status.

Diagnostic laparoscopy may be a useful option for definitively ruling out the lethal conditions associated with pneumatosis intestinalis in frail elderly patients with severe conditions in the emergency setting.

The aim of this study was to investigate the diagnostic performance of contrast-enhanced CT (CECT) findings for bowel ischemia and necrosis in closed-loop small-bowel obstruction (CL-SBO).

Thirty-five patients with CL-SBO confirmed by laparotomy (n = 34) or multiplanar reconstruction of thin slice CT images (n = 1) were included. Based on the surgical and clinical findings, these patients were classified into three groups: necrosis group (n = 16), ischemia without necrosis group (n = 11), and no-ischemia group (n = 8). Two blinded radiologists retrospectively reviewed CECT including multiplanar reconstruction images and evaluated 12 CT findings. The sensitivity and specificity of each finding were compared among the three groups, and logistic regression analysis was performed.

High attenuation of the bowel wall, intraperitoneal air, reduced enhancement of the mesenteric arteries, and small-bowel feces signs showed high specificities of 100%, 100%, 89%, and 89% but low sensitivities of 31%, 25%, 44%, and 31%, respectively, for the prediction of bowel necrosis in CL-SBO. According to multivariate logistic regression analysis, reduced bowel-wall enhancement, reduced enhancement of the mesenteric veins, and a lack of engorgement of the mesenteric veins were significant for predicting bowel ischemia or necrosis (P < 0.05).

Reduced enhancements of bowel wall and mesenteric veins were good indicators of bowel ischemia or necrosis. On the contrary, engorgement of the mesenteric veins was a predictor of a viable bowel.

Purpose To determine whether adding unenhanced computed tomography (CT) to contrast material-enhanced CT improves the diagnostic performance of decreased bowel wall enhancement as a sign of ischemia complicating mechanical small bowel obstruction (SBO). Materials and Methods This retrospective study was approved by the institutional review board, which waived the requirement for informed consent. Two gastrointestinal radiologists independently performed retrospective assessments of 164 unenhanced and contrast-enhanced CT studies from 158 consecutive patients (mean age, 71.2 years) with mechanical SBO. The reference standard was the intraoperative and/or histologic diagnosis (in 80 cases) or results from clinical follow-up in patients who did not undergo surgery (84 cases). Decreased bowel wall enhancement was evaluated with contrast-enhanced images then and both unenhanced and contrast-enhanced images 1 month later. Diagnostic performance of decreased bowel wall enhancement and confidence in the diagnosis were compared between the two readings by using McNemar and Wilcoxon signed rank tests. Interobserver agreement was assessed by using κ statistics and compared with bootstrapping. Results Ischemia was diagnosed in 41 of 164 (25%) episodes of SBO. For both observers, adding unenhanced images improved decreased bowel wall enhancement sensitivity (observer 1: 46.3% [19 of 41] vs 65.8% [27 of 41], P = .02; observer 2: 56.1% [23 of 41] vs 63.4% [26 of 41], P = .45), Youden index (from 0.41 to 0.58 for observer 1 and from 0.42 to 0.61 for observer 2), and confidence score (P < .001 for both). Specificity significantly increased for observer 2 (84.5% [104 of 123] vs 94.3% [116 of 123], P = .002), and interobserver agreement significantly increased, from moderate (κ = 0.48) to excellent (κ = 0.89; P < .0001). Conclusion Adding unenhanced CT to contrast-enhanced CT improved the sensitivity, diagnostic confidence, and interobserver agreement of the diagnosis of ischemia, a complication of mechanical SBO, on the basis of decreased bowel wall enhancement. (©) RSNA, 2016.

This is a review of small-bowel obstruction written primarily for residents. The review focuses on radiography and computed tomography (CT) for diagnosing small-bowel obstruction and CT for determining complications. (©) RSNA, 2015.

Small-bowel obstruction (SBO) represents as many as 16% of surgical admissions and more than 300,000 operations annually in the United States. The optimal strategies for the diagnosis and management of SBO continue to evolve secondary to advances in imaging techniques, critical care, and surgical techniques. This updated systematic literature review was developed by the Eastern Association for the Surgery of Trauma to provide up-to-date evidence-based recommendations for SBO.

A search of the National Library of Medicine MEDLINE database was performed using PubMed interface for articles published from 2007 to 2011.

The search identified 53 new articles that were then combined with the 131 studies previously reviewed by the 2007 guidelines. The updated guidelines were then presented at the 2012 annual EAST meeting.

Level I evidence now exists to recommend the use of computed tomographic scan, especially multidetector computed tomography with multiplanar reconstructions, in the evaluation of patients with SBO because it can provide incremental clinically relevant information over plains films that may lead to changes in management. Patients with evidence of generalized peritonitis, other evidence of clinical deterioration, such as fever, leukocytosis, tachycardia, metabolic acidosis, and continuous pain, or patients with evidence of ischemia on imaging should undergo timely exploration. The remainder of patients can safely undergo initial nonoperative management for both partial and complete SBO. Water-soluble contrast studies should be considered in patients who do not clinically resolve after 48 to 72 hours for both diagnostic and potential therapeutic purposes. Laparoscopic treatment of SBO has been demonstrated to be a viable alternative to laparotomy in selected cases.