Article: Becker BA, Lahham S, Gonzales MA, Nomura JT, Bui MK, Truong TA, Stahlman BA, Fox JC, Kehrl T. A Prospective, Multicenter Evaluation of Point-of-care Ultrasound for Small-bowel Obstruction in the Emergency Department. Acad Emerg Med. 2019 Aug;26(8):921-930. doi: 10.1111/acem.13713. Epub 2019 Mar 12. PMID: 30762916.
The Concept: Historically, Computer Tomography has been the imaging modality of choice over traditional radiography due to its increased specificity and sensitivity when diagnosing Small Bowel Obstructions (SBO). However, the use of point-of-care ultrasound (POCUS) for the evaluation of SBO has grown in recent years and ultrasound is increasingly being touted as a first-line imaging modality for SBO. This study aimed to compare the diagnostic accuracy of Emergency Physicians by use of POCUS for the diagnosis of SBO compared to CT.
The Study: A prospective, observational study at 2 suburban, academic community hospitals and one large urban, university-based tertiary referral center between July 2014 and May 2017.
Inclusion Criteria: Patients were eligible for enrollment if they were at least 18 years of age, able to provide consent in English, not pregnant, had not yet undergone radiology imaging, and presented with symptoms concerning for possible SBO.
Exclusion Criteria: Patients were excluded if they did not receive CT imaging.
Data was collected using standardized data collection forms for all participants. Sonographic data using a curvilinear probe while the patient lay supine and bedside interpretations were recorded at the time of POCUS. Clinical features were also recorded at the time of POCUS, including diarrhea within 24 hours, vomiting, duration of symptoms, timing of last bowel movement, and presence of diffuse abdominal pain or tenderness. Follow-up data were collected by review of the electronic medical record.
The primary outcome of the study was POCUS mediated diagnosis of SBO, confirmed by CT. Secondary outcomes included the diagnosis of SBO by blinded expert interpretation of POCUS images and diagnostic accuracy of each of the five specific sonographic parameters (1.Small bowel dilation ≥ 25 mm, 2.Abnormal peristalsis, 3.Intraperitoneal free fluid, 4.Small-bowel wall edema, 5.Transition point).
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 of 0.88 (95% confidence interval [CI] = 0.80 to 0.94), specificity of 0.54 (95% CI = 0.45 to 0.63), positive likelihood ratio of 1.92 (95% CI = 1.56 to 2.35), and negative likelihood ratio of 0.22 (95% CI = 0.12 to 0.39).
Takeaway: Point-of-care ultrasound is a useful tool for evaluation of small-bowel obstruction. It is sensitive (0.88), although less specific (0.54), as performed by a diverse group of emergency physicians across multiple EDs. Interpretation of acquired point-of-care ultrasound images is significantly more accurate when performed by physicians with prior emergency ultrasound fellowship training and familiarity with the typical sonographic appearance of small bowel obstruction.
Author: Axel Val Schlossberg Pereda, MS4