Diagnostic accuracy of ultrasound for small bowel obstruction: A systematic review and meta-analysis

Intestinal Ultrasound in Common Gastrointestinal Disorders: An Evidence-Based Approach

Patients with abdominal symptoms are among the most common to present both urgently and non-urgently for medical evaluation. While intestinal ultrasound (IUS) is useful to aid management of these patients, it is not routinely taught, performed, or included as part of the core set of point-of-care ultrasound competencies. The authors present an approach to performing a systematic, but focused, IUS at the bedside and diagnostic accuracies for small bowel obstruction inflammatory bowel disease, appendicitis, and diverticulitis. An approach on how to integrate IUS findings and common pitfalls will also be discussed.

The Impact of Point-of-Care Ultrasound on the Diagnosis and Management of Small Bowel Obstruction in the Emergency Department: A Retrospective Observational Single-Center Study

Background and Objectives: Small bowel obstruction (SBO) requires prompt diagnosis and management. Due to its advantages, POCUS can be beneficial when assessing SBO. However, it is still doubtful whether POCUS performed by an emergency doctor can prolong the time of patients with SBO in the emergency department (ED). The primary outcome was time to diagnosis when using POCUS compared to not using it. Secondary outcomes included the processing time in the ED, ED length of stay (LOS), rates of abdominal radiography, hospital LOS, and mortality. Materials and Methods: We conducted a retrospective, observational study in our ED from 1 November 2021 to 31 December 2023, including patients aged 18 and older diagnosed with SBO. Both groups received confirmation of their diagnosis through contrast-enhanced computed tomography. The two groups of patients (POCUS group vs. non-POCUS group) were compared regarding the time needed to reach the final diagnosis (i.e., time to diagnosis), the ED LOS, the hospital LOS, and in-hospital mortality. Results: A total of 106 patients were included. The median time to diagnosis was 121 min for the POCUS group vs. 217 min for the non-POCUS group (p < 0.001). Median ED processing time was 276 min in the POCUS group compared to 376 min in the non-POCUS group (p = 0.006). ED LOS was also shorter in the POCUS group (333 vs. 436 min, p = 0.010). Abdominal X-ray rates were lower in the POCUS group (49% vs. 78%, p = 0.004). Hospital LOS was similar between the two groups (p = 1.000). Five non-POCUS patients died during hospitalization; none died in the POCUS group, but the difference was not statistically significant (p = 0.063). Conclusions: POCUS significantly reduced time to diagnosis and ED LOS. Further exploration is needed to assess long-term outcomes and the cost-effectiveness of integrating POCUS into ED practice.

Gastrointestinal and Biliary Point-of-Care Ultrasound

Point-of-care ultrasound has been shown to have excellent diagnostic accuracy for a variety of gastrointestinal and biliary pathologies. This review explores the evidence and scanning techniques for hypertrophic pyloric stenosis, intussusception, appendicitis, small bowel obstruction, diverticulitis, hernias, pneumoperitoneum, and biliary pathology.

Optimal bowel diameter thresholds for diagnosing small bowel obstruction and surgical intervention with point-of-care ultrasound

OBJECTIVES

A bowel diameter threshold of ≥2.5 cm, originally derived from the research using computed tomography, is frequently used for diagnosing small bowel obstruction (SBO) with point-of-care ultrasound (POCUS). We sought to determine the optimal bowel diameter threshold for diagnosing SBO using POCUS and its accuracy in predicting surgical intervention.

METHODS

We conducted a secondary analysis using individual patient-level data from a previous systematic review on POCUS for SBO diagnosis across five academic EDs. Patient data were collected, including imaging results, surgical findings, and final diagnosis. The measured diameter of the small bowel using POCUS was recorded. ROC area under the receiver operating characteristic curves (AUC) were constructed to determine the optimal threshold for bowel diameter in predicting SBO diagnosis and surgical intervention. Subgroup analyses were performed based on sex and age.

RESULTS

A total of 403 patients had individual patient-level data available, with 367 patients included in the final analysis. The most accurate bowel diameter overall for predicting SBO was 2.75 cm (AUC = 0.76, 95% CI 0.71-0.81). A bowel diameter of ≤1.7 cm had 100% sensitivity with no miss rate, while a bowel diameter of ≥4 cm had 90.7% specificity in confirming SBO. Patients under 65 had an optimal threshold of 2.75 cm versus 2.95 cm in patients over 65. Females had an optimal threshold of 2.75 cm, while males had a value of 2.95 cm. There was no significant correlation between bowel diameter thresholds and surgical intervention.

CONCLUSION

A bowel diameter threshold of 2.75 cm on POCUS is more discriminative diagnostic accuracy for diagnosing SBO. Patients' age and sex may impact diagnostic accuracy, suggesting that tailored approaches may be needed.

Multi-center analysis of point-of-care ultrasound for small bowel obstruction: A systematic review and individual patient-level meta-analysis

OBJECTIVE

The study aimed to assess the diagnostic accuracy of point-of-care ultrasound (POCUS) in identifying small bowel obstruction (SBO) and to investigate the impact of clinician experience level and body mass index (BMI) on POCUS performance for diagnosing SBO in the Emergency Department.

METHODS

We systematically searched PubMed and Cochrane databases from January 2011-2022. We performed a meta-analysis using individual patient-level data from prospective diagnostic accuracy studies from which we obtained data from the corresponding authors. Overall test characteristics and subgroup analysis across clinician experience levels and a range of BMI were calculated. The primary outcome was SBO as the final diagnosis during hospitalization.

RESULTS

We included Individual patient data from 433 patients from 5 prospective studies. Overall, 33% of patients had a final diagnosis of SBO. POCUS had 83.0% (95%CI 71.7%-90.4%) sensitivity and 93.0% (95%CI 55.3%-99.3%) specificity; LR+ was 11.9 (95%CI 1.2-114.9) and LR- was 0.2 (95%CI 0.1-0.3). Residents had exhibited a sensitivity of 73.0% (95%CI 56.6%-84.9%) and specificity of 88.2% (95%CI 58.8%-97.5%), whereas attendings had demonstrated a sensitivity of 87.7% (95%CI 71.1%-95.4%) and specificity of 91.4% (95%CI 57.4%-98.8%). Among those patients with BMI<30 kg/m², POCUS showed a sensitivity of 88.6% (95%CI 79.5%-94.7%) and a specificity of 84.0% (95%CI 75.3%-90.6%), while patients with BMI ≥ 30 kg/m² exhibited a sensitivity of 72.0% (95%CI 50.6%-87.9%) and specificity of 89.5% (95%CI 75.2%-97.1%).

CONCLUSIONS

POCUS correctly identified those patients with SBO with high sensitivity and specificity. Diagnostic accuracy was slightly reduced when performed by resident physicians and among patients with a BMI ≥ 30 kg/m².

REGISTRATION

PROSPERO registration number: CRD42022303598.

Gastrointestinal Ultrasound in Emergency Setting

Acute bowel diseases are responsible for more than one third of subjects who were referred to the emergency department for acute abdominal pain and gastrointestinal evaluation. Gastrointestinal ultrasound (GIUS) is often employed as the first imaging method, with a good diagnostic accuracy in the setting of acute abdomen, and it can be an optimal diagnostic strategy in young females due to the radiation exposure related to X-ray and computed tomography methods. The physician can examine the gastrointestinal system in the area with the greatest tenderness by ultrasound, thus obtaining more information and data on the pathology than the standard physical examination. In this comprehensive review, we have reported the most relevant indications and advantages to using ultrasound in the investigation of abdominal acute pain.