Utilizing Point of Care Ultrasound to Evaluate for Small Bowel Obstruction in Emergency Department Patients

Small bowel obstruction (SBO) is a common diagnosis made in the Emergency Department (ED) representing about 15% of hospital admissions for acute abdominal complaints. We sought to investigate if bedside ultrasound as performed by ED physicians is a reliable test to diagnose and rule out SBO.  This was a prospective cohort study of nonconsecutive patients who presented to an academic, suburban ED with a census of approximately 100,000 patients per year between November 2018 and May 2019. Patients with a history of prior abdominal surgeries who presented to the ED with nausea and/or vomiting and had a CT Abdomen and Pelvis with PO contrast ordered by their provider were consented for a bedside ultrasound. Interpretation was performed by the physician performing the study at bedside. The physician performing the study identified the largest loops of bowel in each of the four quadrants and measured the identified loops from bowel wall to bowel wall.  A diameter of greater than 2.5 cm was considered positive for dilated bowel and probable obstruction. At the completion of the study the physician entered their interpretation of the result which was later reviewed by an ultrasound fellowship-trained physician. There were 101 patients included in the study. Study personnel were accurate in 92% of cases. Overall the sensitivity of point of care ultrasound (POCUS) for SBO was 90% (72.7 to 97.8) and specificity was 92% (82.7 to 96.9). The positive and negative likelihood ratios were 10.76 (4.95 to 23.38) and 0.11 (0.04 to 0.33). Given that our study demonstrated a low negative likelihood ratio, those with low probability of an SBO on history could have an ultrasound examination performed at the bedside which could be sufficient to rule out this disease without requiring patients to undergo further imaging.