UC Irvine

Objective

The main objective of this study was to evaluate the accuracy of emergency physician-performed point-of-care ultrasound (POCUS) for the diagnosis of small-bowel obstruction (SBO) compared to computed tomography (CT).

Methods

We performed a prospective, multicenter, observational study examining a convenience sample of adult patients with potential SBO presenting to the emergency department (ED) between July 2014 and May 2017. Each POCUS was interpreted at the bedside by the performing emergency physician and retrospectively by an expert reviewer. Test characteristics were calculated for POCUS, blinded expert interpretation, and specific POCUS parameters.

Results

A total of 217 subjects were included in the primary analysis with an overall SBO prevalence of 42.9%. For the diagnosis of SBO, POCUS demonstrated an overall sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio of 0.88 (95% confidence interval [CI] = 0.80 to 0.94), 0.54 (95% CI = 0.45 to 0.63), 1.92 (95% CI = 1.56 to 2.35), and 0.22 (95% CI = 0.12 to 0.39), respectively. Expert review yielded a similar sensitivity (0.89 [95% CI = 0.81 to 0.95]) with a significantly higher specificity (0.82 [95% CI = 0.74 to 0.88]). The more sensitive sonographic parameters for both POC sonographers and expert reviewers were small-bowel dilation ≥ 25 mm (0.87 [95% CI = 0.79 to 0.93], 0.87 [95% CI = 0.79 to 0.93]) and abnormal peristalsis (0.82 [95% CI = 0.72 to 0.89], 0.85 [95% CI = 0.76 to 0.87]). The more specific parameters for both groups were transition point (0.82 [95% CI = 0.74 to 0.89], 0.98 [95% CI = 0.94 to 1.00]), intraperitoneal free fluid (0.82 [95% CI = 0.74 to 0.89], 0.93 [95% CI = 0.87 to 0.97]), and bowel wall edema (0.76 [95% CI = 0.67 to 0.83], 0.93 [95% CI = 0.87 to 0.97]).

Conclusion

POCUS is moderately sensitive for SBO, although less specific, when performed by a diverse group of emergency physicians across multiple EDs. Interpretation of acquired POCUS images is significantly more accurate when performed by physicians with prior emergency ultrasound fellowship training and familiarity with the sonographic appearance of SBO.