Diagnostic performance of MDCT in identifying closed loop small bowel obstruction

Applications of Artificial Intelligence in Acute Abdominal Imaging

Artificial intelligence (AI) is a rapidly growing field with significant implications for radiology. Acute abdominal pain is a common clinical presentation that can range from benign conditions to life-threatening emergencies. The critical nature of these situations renders emergent abdominal imaging an ideal candidate for AI applications. CT, radiographs, and ultrasound are the most common modalities for imaging evaluation of these patients. For each modality, numerous studies have assessed the performance of AI models for detecting common pathologies, such as appendicitis, bowel obstruction, and cholecystitis. The capabilities of these models range from simple classification to detailed severity assessment. This narrative review explores the evolution, trends, and challenges in AI applications for evaluating acute abdominal pathologies. We review implementations of AI for non-traumatic and traumatic abdominal pathologies, with discussion of potential clinical impact, challenges, and future directions for the technology.

Small Bowel Obstruction in Virgin Abdomen: Predictors of Surgical Intervention Need in Resource-Limited Setting

Background

Limited evidence is available regarding the management of small bowel obstruction in the virgin abdomen (SBO-VA), with most studies excluding this entity. This study aims to assess the available data on the treatment outcomes and predictors of surgical intervention in SBO-VA.

Methods

A retrospective cross-sectional study was conducted between 2015 and 2021, including all diagnosed and managed cases of SBO-VA at Al-Nasar Hospital. Patients were divided according to the treatment approach into surgical or conservative groups. Preoperative laboratory and radiologic data were gathered and compared between groups.

Results

During the study period, 67 cases, primarily males (58.2%), with an average age of 52.2±14.4 years were assessed. Common comorbidities included diabetes (20.9%) and hypertension (16.4%). Key symptoms were rebound tenderness (82.1%) and abdominal tenderness (70.1%). The predominant etiology was adhesions (23.9%). About 46.2% received conservative treatment, 53.8% underwent urgent surgery. Conservative treatment failed in 9.4% of cases, and complications arose in 23.9%, with most being fever (17.9%). Factors necessitating surgical management included older age (58.8 ±11.7 vs 44.9 ±13.8 years, p<0.001), previous hospital admission (p<0.001), presence of abdominal tenderness (p=0.030), longer abdominal pain duration (4.0 ±0.9 vs 2.1 ±0.6 days, p<0.001), higher C- reactive protein (p= 0.033), higher white blood cell (p= 0.006), longer time to hospital presentation (75.3 ±17.2 vs 39.0 ±22.8 days, p= <0.001), small bowel thickness ≥3 cm (p=0.009), and reduced bowel enhancement (p <0.001) on computed tomography imaging. In surgical group, the need for ICU admission was higher and hospital stays were shorter than in conservative group and were statistically significant (p<0.05).

Conclusion

The main etiology of SBO-VA in our study was adhesions. Older age, previous hospital admission, longer abdominal pain duration, abdominal tenderness, increased inflammatory markers, and alarm signs on CT scans are the main factors for determining the need for urgent surgical exploration in patients with SBO-VA. To achieve prompt identification and intervention, it is crucial to maintain a high level of vigilance and awareness, even in individuals with no prior surgical history.

Deep learning using computed tomography to identify high-risk patients for acute small bowel obstruction: development and validation of a prediction model : a retrospective cohort study

OBJECTIVE

To build a novel classifier using an optimized 3D-convolutional neural network for predicting high-grade small bowel obstruction (HGSBO).

SUMMARY BACKGROUND DATA

Acute SBO is one of the most common acute abdominal diseases requiring urgent surgery. While artificial intelligence and abdominal computed tomography (CT) have been used to determine surgical treatment, differentiating normal cases, HGSBO requiring emergency surgery, and low-grade SBO (LGSBO) or paralytic ileus is difficult.

METHODS

A deep learning classifier was used to predict high-risk acute SBO patients using CT images at a tertiary hospital. Images from three groups of subjects (normal, nonsurgical, and surgical) were extracted; the dataset used in the study included 578 cases from 250 normal subjects, with 209 HGSBO and 119 LGSBO patients; over 38 000 CT images were used. Data were analyzed from 1 June 2022 to 5 February 2023. The classification performance was assessed based on accuracy, sensitivity, specificity, and area under the receiver operating characteristic curve.

RESULTS

After fivefold cross-validation, the WideResNet classifier using dual-branch architecture with depth retention pooling achieved an accuracy of 72.6%, an area under receiver operating characteristic of 0.90, a sensitivity of 72.6%, a specificity of 86.3%, a positive predictive value of 74.1%, and a negative predictive value of 86.6% on all the test sets.

CONCLUSIONS

These results show the satisfactory performance of the deep learning classifier in predicting HGSBO compared to the previous machine learning model. The novel 3D classifier with dual-branch architecture and depth retention pooling based on artificial intelligence algorithms could be a reliable screening and decision-support tool for high-risk patients with SBO.

Unenhanced CT-based predictive model to identify small bowel necrosis in patients with mechanical small bowel obstruction

OBJECTIVES

To investigate the diagnostic value of unenhanced CT in mechanical small bowel obstruction (SBO) with small bowel necrosis, and to establish a predictive model.

METHODS

From May 2017 to December 2021, the patients with mechanical SBO admitted to our hospital were retrospectively collected. Taking pathology-confirmed small bowel necrosis as the gold standard, the experimental group was composed of patients with small bowel necrosis confirmed by pathology, and the control group was composed of patients with no intestinal necrosis confirmed by surgery or successful conservative treatment with no recurrence of intestinal obstruction during 1-month followed-up.

RESULTS

A total of 182 patients were enrolled in this study, 157 patients underwent surgery, of which 35 patients were accompanied with small bowel necrosis and 122 patients were not (33 patients with ischemic findings at surgery without necrosis). Finally, there were 35 patients in the experimental group and 147 patients in the control group. Multivariable logistic regression showed that increased attenuation of small bowel wall (P = 0.002), diffuse mesenteric haziness (P = 0.010), difference of CT value between mesenteric vessel and aorta (P = 0.025) and U-/C-shaped small bowel loop (P = 0.010) were independent risk factors for the diagnosis of mechanical SBO with small bowel necrosis. Through internal verification, the area under curve (AUC) of the predictive model reached 0.886 (95%CI: 0.824-0.947), and the calibration result was moderate.

CONCLUSION

Multiple features (increased attenuation of small bowel wall; difference of CT values between mesenteric vessel and aorta; diffuse mesenteric haziness; and U-/C-shaped small bowel loop) of unenhanced CT have clinical value in the diagnosis of mechanical SBO with small bowel necrosis. The predictive model based on these four features could achieve satisfactory efficiency.

SURGICAL TREATMENT OF ACUTE SMALL BOWEL OBSTRUCTION: CLINICAL AND LABORATORY PARAMETERS ASSOCIATED WITH STRANGULATION AND EARLY MORTALITY AFTER SURGERY

OBJECTIVE

The aim: The study aimed to evaluate some criteria for preoperative diagnosis of strangulation and significant indicators of the prognosis of short-term outcomes in patients with small bowel obstruction.

PATIENTS AND METHODS

Materials and methods: The results of the treatment of 123 patients aged 18-70 years with SBO were evaluated.

RESULTS

Results: All of these patients underwent emergency surgery, and 22 patients (17.9%) have died. It has been shown that four lab parameters (blood leukocytes, lactate, intestinal fatty acid-binding protein, and C-reactive protein levels) and one instrumental (involving the mesentery of the small intestine, free fluid in the abdomen during CT) with 80% probability or more were associated with the strangulation type of SBO (Λ=0.276, p = 0.000). Three lab indicators (WBC count, serum lactate, and intestinal fatty acid-binding protein levels) and two clinical parameters (abdominal perfusion pressure level and the presence of abdominal sepsis) were associated with early mortality after surgery (Λ=0.626, p = 0.000) with the same probability. Immediate results of the treatment in these patients depended on the development of intra-abdominal complications after surgery (P = 0.024) and the need for early reoperation (P = 0.006) as well as the development of cardiovascular dysfunction (P = 0.000) and respiratory dysfunction (P = 0.000).

CONCLUSION

Conclusions: There were confirmed parameters that were significantly associated with strangulation before surgery and short-term in-hospital mortality with an 80% probability or more. This made it possible to develop new mathematical models for the diagnosis of strangulated bowel obstruction and early postoperative mortality with an accuracy of 84.5% and 84.2%, respectively.

Diagnostic nomogram for closed-loop small bowel obstruction requiring emergency surgery

PURPOSE

This study aimed to build a diagnostic model of closed-loop small bowel obstruction (CL-SBO) using clinical information, blood test results, and computed tomography (CT) findings.

METHODS

All patients who were diagnosed with small bowel obstruction (SBO) and underwent surgery between January 1, 2018, and October 31, 2021, in the affiliated hospital of Qingdao university were reviewed, and their relevant preoperative information was collected. All variables were selected using univariate analysis and backward stepwise regression to build a diagnostic nomogram model. K-fold cross-validation and bootstrap resampling techniques were used for internal validation, and data from Qingdao Central Hospital were used for external validation. We also evaluated the diagnostic performance of each CT finding and performed subgroup analysis according to bowel ischemia in the closed-loop small bowel obstruction (CL-SBO) group.

RESULTS

A total of 219 patients (95 in the CL-SBO group and 124 in the open-loop small bowel obstruction [OL-SBO] group) were included in our research. D-dimers (median 1085 vs. 690, P = 0.019), tenderness (77.9% vs. 59.7%, P = 0.004), more than one beak sign (65.3% vs. 30.6%, P < 0.001), radial distribution (18.9% vs. 6.5%, P = 0.005), whirl sign (35.8% vs. 8.9%, P < 0.001), and ascites (71.6% vs. 53.2%, P = 0.006) were selected as the predictive variables of the nomogram. This model's Harrell's C statistic was 0.786 (95% confidence interval (CI), 0.724-0.848), and the Brier score was 0.182. The Harrell's C statistic of external validation was 0.784 (95%CI, 0.664-0.905); the Brier score was 0.190. Regarding the CT findings, radial distribution, U/C-shaped loop, and whirl sign had high specificity (93.5%, 96.0%, and 91.1%, respectively), but low sensitivity (18.9%, 8.4%, and 35.8%, respectively). D-dimer levels and tenderness were also associated with bowel ischemia.

CONCLUSION

The nomogram accurately predicted CL-SBO in patients with SBO, and surgery should be considered when patients have a high risk for developing CL-SBO.

Imaging Signs for Determining Surgery Timing of Acute Intestinal Obstruction

We aimed to analyze the computed tomography (CT) imaging signs of bowel wall ischemia in patients with acute intestinal obstruction and construct an imaging prediction model to guide clinical treatment. The CT imaging signs of patients with acute intestinal obstruction diagnosed in our center in recent 6 years were collected for retrospective analysis. The etiology of intestinal obstruction and incidence rate of bowel wall ischemia were recorded, and the specific CT findings of bowel wall ischemia, including mesenteric edema, bowel wall thickening, and fish tooth sign, were analyzed. Among the 302 patients selected, 130 surgically treated patients were eligible for analysis. Bowel wall ischemia in acute intestinal obstruction showed an incidence rate of 14.90%, and the incidence rates of bowel wall ischemia in intra-abdominal hernia, intussusception, incarcerated external abdominal hernia, and volvulus were about 92.30%, 50%, 35.71%, 33.33%, and 12.59%, respectively. The incidence rate of bowel wall ischemia in simple adhesive intestinal obstruction was about 12.59%, and that in malignancy-induced intestinal obstruction was about 6.56%. Univariate analysis revealed 5 factors with statistical significance, including bowel wall thickening, mesenteric edema, bowel wall pneumatosis, ascites, and fish tooth sign. Multivariate logistic regression analysis indicated that fish tooth sign, bowel wall thickening, and mesenteric edema were able to predict bowel wall ischemia, and the corresponding partial regression coefficients were 2.164, 1.129, and 1.173, odds ratios (ORs) were 8.707, 3.093, and 3.232, sensitivity was 0.356, 0.400, and 0.844, and specificity was 0.859, 0.835, and 0.529, respectively. Imaging signs of bowel wall thickening, mesenteric edema, and fish tooth sign are valuable in predicting bowel wall ischemia, among which bowel wall thickening and mesenteric edema have relatively high specificity and fish tooth sign has a relatively high sensitivity. Furthermore, a fish tooth sign has the most favorable predictive value for bowel wall ischemia in acute intestinal obstruction, followed by bowel wall thickening and mesenteric edema.

Predicting the outcome of closed-loop small bowel obstruction by preoperative characteristics

BACKGROUND

Closed-loop small bowel obstruction (CL-SBO) can threaten the viability of the intestine by obstructing a bowel segment at two adjacent points. Prompt recognition and surgery are crucial.

AIM

To analyze the outcomes of patients who underwent surgery for CL-SBO and to evaluate clinical predictors.

METHODS

Patients who underwent surgery for suspected CL-BSO on computed tomography (CT) at a single center between 2013 and 2019 were evaluated retrospectively. Patients were divided into three groups by perioperative outcome, including viable bowel, reversible ischemia, and irreversible ischemia. Clinical and laboratorial variables at presentation were compared and postoperative outcomes were analyzed.

RESULTS

Of 148 patients with CL-SBO, 28 (19%) had a perioperative viable small bowel, 86 (58%) had reversible ischemia, and 34 (23%) had irreversible ischemia. Patients with a higher age had higher risk for perioperative irreversible ischemia [odds ratio (OR): 1.03, 95% confidence interval (CI): 0.99-1.06]. Patients with American Society of Anaesthesiologists (ASA) classification ≥ 3 had higher risk of perioperative irreversible ischemia compared to lower ASA classifications (OR: 3.76, 95%CI: 1.31-10.81). Eighty-six patients (58%) did not have elevated C-reactive protein (> 10 mg/L), and between-group differences were insignificant. Postoperative in-hospital stay was significantly longer for patients with irreversible ischemia (median 8 d, P = 0.001) than for those with reversible ischemia (median 6 d) or a viable bowel (median 5 d). Postoperative morbidity was significantly higher in patients with perioperative irreversible ischemia (45%, P = 0.043) compared with reversible ischemia (20%) and viable bowel (4%).

CONCLUSION

Older patients or those with higher ASA classification had an increased risk of irreversible ischemia in case of CL-SBO. After irreversible ischemia, postoperative morbidity was increased.

Machine Learning Based Prediction Model for Closed-Loop Small Bowel Obstruction Using Computed Tomography and Clinical Findings

PURPOSE

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

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Adhesion-related small bowel obstruction: deep learning for automatic transition-zone detection by CT

Background

To train a machine-learning model to locate the transition zone (TZ) of adhesion-related small bowel obstruction (SBO) on CT scans.

Materials and methods

We used 562 CTs performed in 2005–2018 in 404 patients with adhesion-related SBO. Annotation of the TZs was performed by experienced radiologists and trained residents using bounding boxes. Preprocessing involved using a pretrained model to extract the abdominopelvic region. We modeled TZ localization as a binary classification problem by splitting the abdominopelvic region into 125 patches. We then trained a neural network model to classify each patch as containing or not containing a TZ. We coupled this with a trained probabilistic estimation of presence of a TZ in each patch. The models were first evaluated by computing the area under the receiver operating characteristics curve (AUROC). Then, to assess the clinical benefit, we measured the proportion of total abdominopelvic volume classified as containing a TZ for several different false-negative rates.

Results

The probability of containing a TZ was highest for the hypogastric region (56.9%). The coupled classification network and probability mapping produced an AUROC of 0.93. For a 15% proportion of volume classified as containing TZs, the probability of highlighted patches containing a TZ was 92%.

Conclusion

Modeling TZ localization by coupling convolutional neural network classification and probabilistic localization estimation shows the way to a possible automatic TZ detection, a complex radiological task with a major clinical impact.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13244-021-01150-y.

Evaluation of ischemia and necrosis in adhesive small bowel obstruction based on CT signs: Subjective visual evaluation and objective measurement

PURPOSE

To investigate the diagnostic performance of CT signs for detecting bowel ischemia and necrosis in adhesive small bowel obstruction(SBO) with subjective and objective methods.

MATERIALS AND METHODS

113 adhesive SBO patients were enrolled and divided into ischemic group (49 cases in necrotic group and 35 cases in reversible ischemic group) and non-ischemic group (29 cases) according to the operation results. Subjective visual assessment of CT signs associated with ischemia and necrosis was performed by two radiologists independently. Elevated unenhanced attenuation and enhancement value of involved bowel wall were objectively measured and compared by single factor analysis of variance. Cut-off value and diagnostic performance were evaluated by receiver operating characteristic curve (ROC).

RESULTS

Closed-loop mechanism, reduced bowel wall enhancement, and mesenteric edema were associated with bowel ischemia, with sensitivity of 81.0%, 65.5%, 75.0%, and specificity of 86.2%, 96.6%, 89.7%, respectively. Increased unenhanced bowel wall attenuation was a specific sign for necrosis with 100.0% specificity and 51.0% sensitivity. The sensitivity and specificity for ischemia were 86.0% and 91.9% with cut-off enhancement value lower than 33.5 HU. The sensitivity and specificity for necrosis were 58.2% and 100.0% with cut-off elevated unenhanced attenuation higher than 16.5 HU, 86.7% and 83.3% with cut-off enhancement value lower than 21.5 HU.

CONCLUSION

Reduced bowel wall enhancement and increased unenhanced bowel wall attenuation were good indicators of bowel ischemia and necrosis. The objective measurement of elevated unenhanced attenuation and enhancement value can predict bowel ischemia and necrosis more accurately.

Correlation of CT findings with intra-operative outcome in closed-loop small bowel obstruction (CL-SBO)

PURPOSE

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.

METHODS

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.

RESULTS

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).

CONCLUSION

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.

Diagnosis and management of small bowel obstruction in virgin abdomen: a WSES position paper

Background

Small bowel obstruction (SBO) is a common surgical emergency, causing high morbidity and healthcare costs. The majority of SBOs are caused by adhesions that result from previous surgeries. Bowel obstruction, however, also occurs in patients without previous operation or known pathology, a so called virgin abdomen. It is unknown if small bowel obstruction in the virgin abdomen (SBO-VA) can be managed according to the same principles as other cases of small bowel obstruction. The aim of this position paper is to evaluate the available evidence on etiology and management of small bowel obstruction in the virgin abdomen.

Methods

This is a narrative review with scoping aspects. Clinical topics covered in this review include epidemiology and etiology of SBO-VA, diagnosis and imaging, initial assessment, the role of surgical management in SBO-VA, and the role of non-operative management in SBO-VA.

Results

Our scoping search revealed seven original studies reporting original patient data related to SBO-VA. All the included studies are retrospective cohorts, with populations ranging between 44 and 103 patients with SBO-VA. Adhesions were found to be the cause of the obstruction in approximately half of the reported cases of SBO-VA. A relatively high number of cases of SBO-VA were managed surgically with studies reporting 39–83%. However, in cases where a trial of non-operative management was started, this was generally successful.

Conclusion

The data available suggest that etiology and treatment results for patients with SBO-VA are largely comparable to the results in patients with SBO after previous abdominal surgery. We therefore propose that patients with a virgin abdomen could be treated according to existing guidelines for SBO and adhesive small bowel obstruction.

Adhesive small bowel obstruction: Single band or matted adhesions? A predictive model based on computed tomography scan

BACKGROUND

Preoperative identification of the cause of adhesive small bowel obstruction (ASBO) is crucial for decision making. Some computed tomography (CT) findings can be indicative of single adhesive bands or matted adhesions. Our aim was to build a predictive model based on CT data to discriminate ASBO due to single adhesive band or matted adhesions.

METHODS

A retrospective single center study was conducted, covering all consecutive patients with a preoperative CT scan, undergoing urgent surgery for ASBO between January 1, 2005, and December 31, 2017. Preoperative CT scans were blindly reviewed, and all the CT findings indicative of single adhesive band or matted adhesions described in literature were recorded. According to intraoperative findings, ASBOs were retrospectively classified into single band and matted ASBO. All observed CT findings were compared between the two groups. A predictive model based on logistic regression was developed, and its ability was quantified by discrimination and calibration. Internal cross-validation was conducted by bootstrap resampling.

RESULTS

A total of 116 patients were analyzed (males, 53.5%; median age, 68 years; single band ASBO in 65.5% of cases). The odds of single band ASBO were increased four times in presence of complete obstruction (odds ratios, 4.19; 95% confidence interval, 1.49-12.56) and seven times in presence of fat notch sign (odds ratios, 7.37; 95% confidence interval, 1.83-40.03). The predictive model combining all CT findings had an accuracy of 86% in single band ASBO prediction. Accuracy decreased to 79% in the internal validation. Sensitivity, specificity, and positive and negative predictive values were calculated at different cut-points of the predicted risk: using a 0.70 cut-point, the specificity is 80%, the sensitivity is 68%, and the positive and negative predictive values are 87% and 57%, respectively.

CONCLUSION

The proposed predictive model based on combination of specific CT findings may elucidate whether ASBO is caused by single bands or matted adhesions and, consequently, influence the clinical pathway.

LEVEL OF EVIDENCE

Prognostic study, level IV.

Pneumatosis intestinalis and portal venous gas in mechanical small bowel obstruction: Is it worrisome?

PURPOSE

The purpose of this study was to evaluate the clinical significance of pneumatosis intestinalis (PI) and portal venous gas (PVG) in patients with mechanical small bowel obstruction (SBO), using surgical findings or clinical follow-up as standard of reference.

MATERIALS AND METHODS

Fourteen patients with mechanical SBO associated with PI and PVG were retrospectively included. There were 7 men and 7 women with a mean age of 59±19 (SD) (range: 25-93 years). CT examinations were reviewed by two radiologists to confirm the diagnosis of mechanical SBO and make a description of PI. Interobserver agreement was calculated. The reference standard was intraoperative appearance of the bowel wall (10/14; 71%) or the recovery of a normal bowel function in patients who were managed conservatively (4/14; 29%).

RESULTS

Among the 10 patients who underwent surgery, a normal appearance of the bowel in association with PI on CT was found intraoperatively in 8/10 (80%) patients and a reversible ischemia in the remaining 2/10 (20%) patients. The four patients who were managed conservatively recovered normal bowel function. Two patients died within two weeks following SBO.

CONCLUSION

PI and PVG are not specific signs of bowel necrosis in mechanical SBO.

Non-operative management of small bowel obstruction in virgin abdomen: a systematic review

The aim of this study was to systematically review the feasibility and safety of non-operative management of small bowel obstruction (SBO) in virgin abdomen. A systematic review was performed through December 2019. The primary outcome was the resolution of non-operative management of SBO in virgin abdomen. Secondary outcomes were the etiology of SBO and findings of exploratory laparotomy. Six studies were included in the analysis. Of the 442 patients, 2 with metastatic cancer received palliative care, and the management in 26 was not reported, so these patients were excluded. A total of 414 patients were ultimately analyzed, including 203 patients (49%) who were managed non-operatively and 211 (51%) who underwent surgical management. Of the 203 managed non-operatively, the condition of 194 (96%) was resolved without further intervention. The remaining 9 (5%) patients failed non-operative management and ultimately required surgery. Of the 211 patients who underwent surgical exploration, only 137 had their intraoperative findings reported. Adhesions (n = 67; 49%) were the main cause, followed by malignancy (n = 14; 10%) and others (n = 33; 24%). No cause was found in 23 patients (17%). In highly select cases of SBO with virgin abdomen, non-operative management can be attempted if patients are clinically stable and computed tomography does not demonstrate concerning features or obvious pathology. Further well-designed prospective studies will be required prior to the introduction of this concept in clinical practice, as current evidence remains heterogeneous.

Adhesive Small Bowel Obstruction: Predictive Radiology to Improve Patient Management

Adhesive small bowel obstruction (SBO) remains one of the leading causes of emergency room visits and is still associated with high morbidity and mortality rates. Because the management of adhesive SBO has shifted from immediate surgery to nonoperative treatment in the absence of ischemia, it is crucial to rapidly detect or predict strangulation, which requires emergent surgery. CT is now established as the best imaging technique for the initial assessment of patients suspected of having adhesive SBO. CT helps confirm the diagnosis of mechanical SBO, locate the site of obstruction, establish the cause, and detect complications. This article is a review of the role of imaging in answering specific questions to help predict the management needs of each individual patient. It includes (a) an update on the best CT signs for predicting ischemia and a need for bowel resection; (b) a discussion of the CT features that help differentiate open-loop from closed-loop obstruction and a single adhesive band from matted adhesions and how these differences can influence the management; and (c) a review of the main CT predictors of the success or failure of nonoperative management in adhesive SBO.

Diagnostic significance of multidetector computed tomography (MDCT) in patients with small bowel obstruction: a meta-analysis

PURPOSE

To assess the diagnostic value of multidetector computed tomography (MDCT) in small bowel obstruction (SBO) patients.

METHODS

Relevant literature was searched from the Cochrane Library, Pubmed and Embase. The extracted effective data was calculated using the Meta-Disc 1.4 software; statistical heterogeneity was evaluated using Cochran's Q test and I².

RESULTS

A total of five articles were selected for the meta-analysis. In addition, the pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), as well as the diagnostic odds ratio (DOR) were 0.878 (95% CI 0.822-0.921), 0.807 (95% CI 0.753-0.854), 8.137 (95% CI 2.268-29.192), 0.127 (95% CI 0.040-0.4078) and 72.384 (95% CI 10.841-483.31), respectively. Furthermore, the AUC was 0.9648 with the Q of 0.9116.

CONCLUSIONS

The data suggest that MDCT is an effective method for diagnosis of SBO.

Clinical Effect of Water-Soluble Contrast Agents for Small Bowel Obstruction in the Virgin Abdomen

BACKGROUND

Several studies have investigated the diagnostic and therapeutic role of water-soluble contrast agents (WSCAs) in adhesive small bowel obstruction (SBO). However, the clinical effect of WSCA for SBO without previous intraabdominal operation (i.e., virgin abdomen, VA) is unclear. The aim of this study was to clarify the clinical effect of WSCA for SBO in the VA.

METHODS

Between January 2008 and December 2015, 838 consecutive patients with SBO were initially managed with WSCA and were included in the study. Abdominal X-rays were taken 5 h after administration of 100 ml WSCA and classified into complete/incomplete obstruction groups. The medical records of the patients with SBO were retrospectively analyzed and divided into two groups of patients with VA or non-VA.

RESULTS

A total of 44 and 794 VA and non-VA patients were identified, respectively. Six VA patients (13%) and 121 non-VA patients (15%) were classified with complete obstruction (p = 1.000) and subjected to operative exploration on the same day. There were no significant differences in the duration of nasogastric tube decompression (2.2 versus 2.5 days, p = 0.400) and intervals until the initiation of oral intake (2.4 versus 2.6 days, p = 0.553) between the VA and non-VA groups. The overall operative rate was 16% in the VA and 17% in the non-VA groups (p = 1.000). Compared with non-VA, VA was associated with shorter hospital stays (9.6 versus 11.3 days, p = 0.006).

CONCLUSIONS

WSCA for SBO in the VA is as effective as in non-VA patients in terms of a therapeutic strategy.

A Systematic Review of the Clinical Presentation, Diagnosis, and Treatment of Small Bowel Obstruction

PURPOSE OF REVIEW

This study aimed to systematically review small bowel obstruction (SBO), focusing on recent changes in diagnosis/therapy.

RECENT FINDINGS

SBO incidence is about 350,000/annum in the USA. Etiologies include adhesions (65%), hernias (10%), neoplasms (5%), Crohn's disease (5%), and other (15%). Bowel dilatation occurs proximal to obstruction primarily from swallowed air and secondarily from intraluminal fluid accumulation. Dilatation increases mural tension, decreases mucosal perfusion, causes bacterial proliferation, and decreases mural tensile strength that increases bowel perforation risks. Classical clinical tetrad is abdominal pain, nausea and emesis, abdominal distention, and constipation-to-obstipation. Physical exam may reveal restlessness, acute illness, and signs of dehydration and sepsis, including tachycardia, pyrexia, dry mucous membranes, hypotension/orthostasis, abdominal distention, and hypoactive bowel sounds. Severe direct tenderness, involuntary guarding, abdominal rigidity, and rebound tenderness suggest advanced SBO, as do marked leukocytosis, neutrophilia, bandemia, and lactic acidosis. Differential diagnosis includes postoperative ileus, narcotic bowel, colonic pseudo-obstruction, mesenteric ischemia, and large bowel obstruction. Medical resuscitation includes intravenous hydration, correcting electrolyte abnormalities, intravenous antibiotics, nil per os, and nasoenteral suction. Abdominal CT with oral and intravenous gastrografin contrast is highly sensitive and specific in detecting/characterizing SBO. SBO usually resolves with medical therapy but requires surgery, preferentially by laparoscopy, for unremitting total obstruction, bowel perforation, severe ischemia, or clinical deterioration with medical therapy. Overall mortality is 10% but increases to 30% with bowel necrosis/perforation. Key point in SBO is early diagnosis, emphasizing abdominal CT; aggressive medical therapy including rehydration, antibiotics, and nil per os; and surgery for failed medical therapy.