Features on MDCT that predict surgery in patients with adhesive-related small bowel obstruction

Prognostic factors to identify resolution of small bowel obstruction without need for operative management: systematic review

OBJECTIVES

To identify imaging, clinical, and laboratory variables potentially prognostic for surgical management of small bowel obstruction.

METHODS

Two researchers systematically reviewed indexed literature 2001-2021 inclusive for imaging, clinical, and laboratory variables potentially predictive of surgical management of small bowl obstruction and/or ischaemia at surgery, where performed. Risk of bias was assessed. Contingency tables for variables reported in at least 5 studies were extracted and meta-analysed to identify strong evidence of association with clinical outcomes, across studies.

RESULTS

Thirty-one studies were ultimately included, reporting 4638 patients (44 to 313 per study). 11 (35%) studies raised no risk of bias concerns. CT was the modality reported most (29 studies, 94%). Meta-analysis of 21 predictors identified 5 strongly associated with surgical intervention, 3 derived from CT (peritoneal free fluid, odds ratio [OR] 3.24, 95%CI 2.45 to 4.29; high grade obstruction, OR 3.58, 95%CI 2.46 to 5.20; mesenteric inflammation, OR 2.61, 95%CI 1.94 to 3.50; abdominal distension, OR 2.43, 95%CI 1.34 to 4.42; peritonism, OR 3.97, 95%CI 2.67 to 5.90) and one with conservative management (previous abdominopelvic surgery, OR 0.58, 95%CI 0.40 to 0.85). Meta-analysis of 10 predictors identified 3 strongly associated with ischaemia at surgery, 2 derived from CT (peritoneal free fluid, OR 3.49, 95%CI 2.28 to 5.35; bowel thickening, OR 3.26 95%CI 1.91 to 5.55; white cell count, OR 4.76, 95%CI 2.71 to 8.36).

CONCLUSIONS

Systematic review of patients with small bowel obstruction identified four imaging, three clinical, and one laboratory predictors associated strongly with surgical intervention and/or ischaemia at surgery.

CLINICAL RELEVANCE STATEMENT

Via systematic review and meta-analysis, we identified imaging, clinical, and laboratory predictors strongly associated with surgical management of small bowel obstruction and/or ischaemia. Multivariable model development to guide management should incorporate these since they display strong evidence of potential utility.

KEY POINTS

• While multivariable models incorporating clinical, laboratory, and imaging factors could predict surgical management of small bowel obstruction, none are used widely. • Via systematic review and meta-analysis we identified imaging, clinical, and laboratory variables strongly associated with surgical management and/or ischaemia at surgery. • Development of multivariable models to guide management should incorporate these predictors, notably CT scanning, since they display strong evidence of potential utility.

Closed loop obstruction of small bowel: CT signs predicting successful non-surgical treatment

PURPOSE

To clarify the computed tomography (CT) findings related to successful conservative treatments in patients with closed-loop small bowel obstruction (CL-SBO) without evidence of bowel strangulation.

METHODS

Sixty-four patients (71 CT scans) diagnosed with CL-SBO by CT and received initial conservative treatments from May 2010 to August 2020 were retrospectively included. Two blinded radiologists reviewed the CT findings, including the transition zone (number, distance, and location), maximum bowel diameter, mesenteric haziness, mesenteric fluid, increased unenhanced bowel wall attenuation, decreased bowel wall enhancement, small bowel feces sign, whirl sign, bowel wall thickening, ascites, and degree of obstruction. The findings of the success and failure groups of conservative treatment were compared. Interobserver agreement was assessed for all findings.

RESULTS

Among the 71 cases, conservative treatments were successful in 42 cases (59 %) but failed in 29 cases (41 %). In multivariable analyses, the distance between the transition zones (>1 cm) and low-degree obstruction were independently associated with successful conservative treatments, with odds ratios of 6.23 and 3.52, respectively. The combination of these two CT findings exhibited a specificity of 89.7 % with a positive likelihood ratio of 3.01. Interobserver agreement of the degree of obstruction and the distance between the transition zones was almost perfect (ĸ = 0.814 and 0.914, respectively).

CONCLUSIONS

The distance between the transition zones (>1 cm) and low-grade obstruction are independent CT predictors of successful conservative treatments in CL-SBO patients. Initial conservative treatments are recommended for patients with both CT findings.

Comprehensively evaluate the short outcome of small bowel obstruction: A novel medical-economic score system

BACKGROUND

Small bowel obstruction (SBO) still imposes a substantial burden on the health care system. Traditional evaluation systems for SBO outcomes only focus on a single element. The comprehensive evaluation of outcomes for patients with SBO remains poorly studied. Early intensive clinical care would effectively improve the short-term outcomes for SBO, however, the full spectrum of the potential risk status regarding the high complication-cost burden is undetermined.

AIM

We aim to construct a novel system for the evaluation of SBO outcomes and the identification of potential risk status.

METHODS

Patients who were diagnosed with SBO were enrolled and stratified into the simple SBO (SiBO) group and the strangulated SBO (StBO) group. A principal component (PC) analysis was applied for data simplification and the extraction of patient characteristics, followed by separation of the high PC score group and the low PC score group. We identified independent risk status on admission via a binary logistic regression and then constructed predictive models for worsened management outcomes. Receiver operating characteristic curves were drawn, and the areas under the curve (AUCs) were calculated to assess the effectiveness of the predictive models.

RESULTS

Of the 281 patients, 45 patients (16.0%) were found to have StBO, whereas 236 patients (84.0%) had SiBO. Regarding standardized length of stay (LOS), total hospital cost and the presence of severe adverse events (SAEs), a novel principal component was extracted (PC score = 0.429 × LOS + 0.444 × total hospital cost + 0.291 × SAE). In the multivariate analysis, risk statuses related to poor results for SiBO patients, including a low lymphocyte to monocyte ratio (OR = 0.656), radiological features of a lack of small bowel feces signs (OR = 0.316) and mural thickening (OR = 1.338), were identified as risk factors. For the StBO group, higher BUN levels (OR = 1.478) and lower lymphocytes levels (OR = 0.071) were observed. The AUCs of the predictive models for poor outcomes were 0.715 (95%CI: 0.635-0.795) and 0.874 (95%CI: 0.762-0.986) for SiBO and StBO stratification, respectively.

CONCLUSION

The novel PC indicator provided a comprehensive scoring system for evaluating SBO outcomes on the foundation of complication-cost burden. According to the relative risk factors, early tailored intervention would improve the short-term outcomes.

Prediction and management of strangulated bowel obstruction: a multi-dimensional model analysis

BACKGROUND

Distinguishing strangulated bowel obstruction (StBO) from simple bowel obstruction (SiBO) still poses a challenge for emergency surgeons. We aimed to construct a predictive model that could distinctly discriminate StBO from SiBO based on the degree of bowel ischemia.

METHODS

The patients diagnosed with intestinal obstruction were enrolled and divided into SiBO group and StBO group. Binary logistic regression was applied to identify independent risk factors, and then predictive models based on radiological and multi-dimensional models were constructed. Receiver operating characteristic (ROC) curves and the area under the curve (AUC) were calculated to assess the accuracy of the predicted models. Via stratification analysis, we validated the multi-dimensional model in the prediction of transmural necrosis both in the training set and validation set.

RESULTS

Of the 281 patients with SBO, 45 (16.0%) were found to have StBO, while 236(84.0%) with SiBO. The AUC of the radiological model was 0.706 (95%CI, 0.617-0.795). In the multivariate analysis, seven risk factors including pain duration ≤ 3 days (OR = 3.775), rebound tenderness (OR = 5.201), low-to-absent bowel sounds (OR = 5.006), low levels of potassium (OR = 3.696) and sodium (OR = 3.753), high levels of BUN (OR = 4.349), high radiological score (OR = 11.264) were identified. The AUC of the multi-dimensional model was 0.857(95%CI, 0.793-0.920). In the stratification analysis, the proportion of patients with transmural necrosis was significantly greater in the high-risk group (24%) than in the medium-risk group (3%). No transmural necrosis was found in the low-risk group. The AUC of the validation set was 0.910 (95%CI, 0.843-0.976). None of patients in the low-risk and medium-risk score group suffered with StBO. However, all patients with bowel ischemia (12%) and necrosis (24%) were resorted into high-risk score group.

CONCLUSION

The novel multi-dimensional model offers a useful tool for predicting StBO. Clinical management could be performed according to the multivariate score.

Computed Tomography in Emergency Diagnosis and Management Considerations of Small Bowel Obstruction for Surgical vs. Non-surgical Approach

BACKGROUND

Small bowel obstruction (SBO) accounts for 15% of abdominal pain complaints referred to emergency departments and imposes significant financial burdens on the healthcare system. The absence of passage of flatus or stool and abdominal distention are reported as the most common symptom and a sign of SBO, respectively. Patients who do not demonstrate severe clinical or imaging findings are typically treated with conservative approaches. Patients with clinical signs of sepsis or physical findings of peritonitis are often instantly transferred to the operating room without supplementary imaging assessment. However, in cases where symptoms are non-specific, or the physical examination is challenging, such as in cases with loss of consciousness, the diagnosis can be complicated. This paper discusses the key findings detectable on Computed tomography (CT), which are vital for the emergent triage, proper treatment, and decision making in patients with speculated SBO.

METHOD

Narrative review of the literature.

RESULTS AND CONCLUSION

CT plays a key role in emergent triage, proper treatment, and decision making. It provides high sensitivity, specificity, and accuracy in the detection of early-stage obstruction and acute intestinal vascular compromise. It can also differentiate between various etiologies of this entity which is considered an important criterion in the triage of patients into surgical vs. non-surgical treatment. There are multiple CT findings, such as mesenteric edema, lack of the small-bowel feces, bowel wall thickening, fat stranding in the mesentery, and intraperitoneal fluid, which are predictive of urgent surgical exploration.

Vascular assessment in small bowel obstruction: can CT predict requirement for surgical intervention?

PURPOSE

Small bowel obstruction (SBO) is a common cause of emergency presentations for abdominal pain and can be complicated by mesenteric ischemia. Computed tomography is currently central to diagnosis and management planning. Currently accepted signs identify secondary effects of the root physiological insult, which is vascular obstruction. We hypothesized that with advancements in CT technology and reconstruction algorithms, we can now more closely interrogate the mesenteric vasculature for obstruction and more accurately predict the need for surgical intervention.

METHODS

We retrospectively audited the charts of all patients presenting with a clinical diagnosis of SBO at a single institution in a 12-month period. Two blinded consultant radiologists were then asked to analyze 3D MIP reconstruction CT scans for vascular obstruction in addition to any currently accepted signs of ischemia. Comparison between vascular cutoff and accepted current signs in the need for surgical intervention and the presence of any signs of ischemia in theater were recorded.

RESULTS

Vascular cutoff had a comparable, with a trend towards superiority, sensitivity and specificity and inter-observer agreement to currently accepted signs of ischemia. The absence of a cut off sign has an excellent negative predictive value for ischemia with only 2 (3.7%) patients demonstrating ischemia at surgery where the vascular cutoff sign was not seen to be present.

CONCLUSION

Interrogating vascular obstruction using 3D MIP reconstructions in small bowel obstruction may be a more sensitive and specific sign for prediction of surgical intervention, possibly occurring earlier in the obstruction pathway.

Computed Tomography Findings Predicting the Need for Surgery in Cases of Small Bowel Obstruction: Emphasis on Duodenal Distension

OBJECTIVE

The aim of the study is to retrospectively evaluate the utility of computed tomography (CT) findings, especially newly defined duodenal distension, for predicting the need to operate on small bowel obstruction (SBO) cases.

METHODS

During a 51-month period, 228 patients (100 women and 128 men; mean age, 55 years) were included in this study, among 438 patients who were hospitalized with a prediagnosis of SBO. The final study population was then divided into 2 groups: a surgery group (n = 76) and a conservative group (n = 152). The CT findings of the SBO patients whose treatment decisions and outcomes were unknown were examined by 2 gastrointestinal radiologists with consensus. Statistical analyses were conducted using univariate and binary logistic regression analyses.

RESULTS

According to the univariate analysis, the degree of obstruction (P = 0.001), small bowel diameter (P = 0.014), and presence of mesenteric fluid (P < 0.001), intraperitoneal free fluid (P = 0.04), intra-abdominal free gas (P < 0.001), and duodenal distension (P < 0.001) showed statistically significant differences between the surgery and conservative groups. However, there were no statistically significant group differences regarding the presence of a transition point, small bowel feces or mesenteric congestion. According to the binary logistic regression analysis, the degree of obstruction (P = 0.012), presence of mesenteric fluid (P = 0.008), intra-abdominal free gas (P = 0.019), and duodenal distension (P < 0.001) were significant predictors of the need for surgery in SBO cases.

CONCLUSIONS

Duodenal distension as a CT finding predicted the need for surgery in SBO cases.

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.

Diagnostic utility of CT for small bowel obstruction: Systematic review and meta-analysis

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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

Application value of multi-slice spiral CT in selection of operative indications in patients with intestinal obstruction

BACKGROUND

Intestinal obstruction is one of the common acute abdominal diseases. In recent years, with the continuous improvement of medical technology, multi-row spiral CT technology has been popularized, which has the advantages of simple operation, high resolution, convenience, and accuracy.

AIM

To explore the application value of multi-slice spiral CT in the selection of surgical indications for intestinal obstruction.

METHODS

The abdominal CT findings of 128 patients who were diagnosed with intestinal obstruction at our hospital from February 2017 to May 2019 were retrospectively analyzed. Signs of intestinal obstruction on abdominal CT images, such as complete obstruction, transitional zone, anterior adhesion, increased abdominal fat density, intestinal fecal sign, whirlpool sign, bird's beak sign, cable sign, and peritoneal effusion, were statistically analyzed to identify the correlation of these factors, alone or in combination, with surgical treatment.

RESULTS

Of the 128 patients included, 36 underwent surgical treatment and 92 recovered after conservative treatment. When comparing the CT signs between the two groups of patients, it was found that the degree of obstruction, transitional zone, anterior adhesion, intestinal fecal sign, increased abdominal fat density, cable sign, bird's beak sign, and peritoneal effusion were statistically different between the two groups (P < 0.05). By Logistic regression analysis, it was found that complete intestinal obstruction, transitional zone, anterior adhesion, intestinal fecal sign, and peritoneal effusion were statistically significant (P < 0.05); the specificity, sensitivity, negative predictive value, positive predictive value, and OR value were all > 1.

CONCLUSION

Complete obstruction, transitional zone, anterior adhesion, intestinal fecal sign and peritoneal effusion are the objective basis for clinical surgeons to choose surgical treatment for intestinal obstruction patients.

Current management of adhesive small bowel obstruction

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.

Bowel Obstruction

Small bowel obstruction and large bowel obstruction account for approximately 20% of cases of acute abdominal surgical conditions. The role of the radiologist is to answer several key questions: Is obstruction present? What is the level of the obstruction? What is the cause of the obstruction? What is the severity of the obstruction? Is the obstruction simple or closed loop? Is strangulation, ischemia, or perforation present? In this presentation, the radiologic approach to and imaging findings of patients with known or suspected bowel obstruction are presented.

Imaging differentiation of phytobezoar and small-bowel faeces: CT characteristics with quantitative analysis in patients with small- bowel obstruction

OBJECTIVE

The objective is to use multidetector computed tomography (MDCT) to differentiate phytobezoar impaction and small-bowel faeces in patients with small-bowel obstruction (SBO).

METHODS

We retrospectively reviewed 91 consecutive SBO patients with surgically proven phytobezoars (n = 31) or adhesion with small-bowel faeces (n = 60). Two readers blinded to the diagnosis recorded the following MDCT features: degree of obstruction, transition point, mesenteric fatty stranding, intraperitoneal fluid, air-fluid level, pneumatosis intestinalis, and portal venous gas. MDCT measurements of the food debris length, attenuation, luminal diameter, and wall thickness of the obstructed bowel were also compared.

RESULTS

A higher grade of obstruction with an absence of mesenteric fatty stranding and intraperitoneal fluid was more commonly seen in the phytobezoar group than in the small-bowel faeces group (p < 0.01). The food debris length (phytobezoar, 5.7 ± 2.8 cm; small-bowel feces, 20.3 ± 7.9 cm, p < 0.01) and mean attenuation (phytobezoar, -59.6 ± 43.3 Hounsfield units (HU); small-bowel faeces, 8.5 ± 7.7 HU, p <0.01) were significantly different between the two groups. The ROC curve showed that food debris length <9.5 cm and mean attenuation value < -11.75 HU predicted phytobezoar impaction.

CONCLUSIONS

MDCT features with measurements of the food debris length and mean attenuation assist the differentiation of phytobezoar impaction and small-bowel faeces.

KEY POINTS

• MDCT examination helps to differentiate phytobezoar and small-bowel faeces. • A higher grade of obstruction is commonly associated with phytobezoar impaction. • Mesenteric fatty stranding and intraperitoneal fluid are frequently associated with small-bowel faeces. • Quantitative measurement of the obstructed bowel adds the diagnostic accuracy.

Small bowel feces sign in association with occlusive mesenteric ischemia

Small bowel feces sign (SBFS) is a computed tomography (CT) finding that appears as fecal like material in dilated small bowel loops. This sign is usually seen in association with gradually progressive small bowel obstruction. We present a case of occlusive mesenteric ischemia in which the SBFS appeared on CT scan early on in the course of the disease. We put forward a suggested alternative mechanism to the appearance of this sign in association with mesenteric ischemia. The SBFS might have the potential to serve as an early sign of mesenteric ischemia on CT scan.