SonoStudy: Emergency docs detect small bowel obstruction by US – as good as radiologists #FOAMed

In a recent article in the European Journal of Emergency medicine, the authors showed that emergency physicians are just as good as radiologists in detecting small bowel obstruction by bedside US. Now, it’s not hard to do, nor is it hard to see it. First off, use your abdominal low frequency probe, and evaluate the abdomen in different quadrants. Normally, the bowel appears as a single circular hypoechoic layer (muscle layer) surrounding hyperechoic bowel contents of gas and food particles. The normal thickness of this layer during the contraction stage of peristalsis is 2-3 mm. The hypoechoic normal wall becomes thinner during peristalsis when the bowel is relaxed.

In small bowel obstruction- looking for dilated fluid filled loops of bowel with hyperechoic (bright) spots within it that may have back and forth peristalsis and a thicker intestinal wall (decreased persitalsis is a late finding) – color doppler gives info about blood flow in the walls of the intestine – and you may even see a transition point. Timothy Jang and team studied ultrasound compared to Xray for SBO and found that ultrasound is better, like WAYYYY better (higher sensitivity and specificity) – hmmm, interesting – Some things to consider: fluid-filled loops (good for US), but air-filled loops may not be so good. Ileus and SBO may appear similarly, so consider thinking of causes of ileus as well (gallstone ileus, etc), and a thickened wall may just be colitis, but that along with dilated loops and back and forth persitalsis with a transition point seen – more likely SBO.

This is what it would look like (and there are more clips to view – thanks to SonoCloud)

The abstract of the study follows:

“Objective: Our objective was to study the accuracy of emergency medicine [(EM) bedside ultrasonography (BUS)] and radiology residents performed ultrasonography (RUS) in patients with suspected mechanical small bowel obstruction (SBO).

Methods: After a 6-h training program, from January to June 2009, four EM residents used BUS to prospectively evaluate the patients presenting to the emergency department with suspected SBO. Then, patients underwent RUS. Outcome was determined by surgical findings if they were operated upon or self-reported the condition upon telephone follow-up at 1-month. BUS and RUS results were compared with χ2 testing.

Results: Of the 174 enrolled patients, 90 patients were BUS-positive. Of these, surgical findings agreed with the BUS findings in 84 patients. In 78 cases, BUS was negative, and 76 of these patients had benign clinical courses. Six patients were excluded from the study. The sensitivity, specificity, positive predictive value, negative predictive value, and likelihood ratio for BUS were 97.7, 92.7, 93.3, 97.4, and 13.4%, respectively. Sensitivity, specificity, positive predictive value, and negative predictive value for RUS were 88.4, 100, 100, and 89.1%, respectively. The diagnostic accuracy of BUS and RUS were not statistically different from each other (κ=0.81). The presence of dilated small bowel loops (>25 mm in jejunum or >15 mm in ileum) was the most sensitive (94%) and specific (94%) sonographic finding for SBO.

Conclusion: Abdominal sonography for the diagnosis of SBO is a new application of BUS in the emergency department. EM residents can diagnose SBO using BUS with a high-degree of accuracy, comparable with that of radiology residents.”

To read the UltrasoundPodcast guys speak on the subject, click here>

To see them do it, see below:

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