Background: There is a considerable overlap between symptoms of irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD). It is important to have access to non-invasive, safe, low cost diagnostic tools to differentiate IBD from functional abdominal symptoms such as IBS, and avoid unnecessary invasive investigations including endoscopy. Point of care ultrasound (POCUS) of the bowel is not widely accessible in North America, but is routinely used in Europe. The aim of this study was to evaluate the accuracy of POCUS in the detection of luminal inflammation compared to gold standard ileocolonscopy in patients presenting with undifferentiated lower gastrointestinal symptoms.
Methods: A prospective, single- center study of consecutive patients presenting to the GI clinic with symptoms high risk for IBD were evaluated to differentiate IBD from IBS. POCUS was performed, clinical data recorded and C-reactive protein measured prior to ileocolonoscopy, which served as the gold standard. Sensitivity, specificity, positive predictive value and negative predictive value were calculated for POCUS.
Results: Eighty-six patients with undifferentiated symptoms of diarrhea (76.7%), abdominal pain (62.8%) and weight loss (18.6%) were evaluated. Nocturnal symptoms (15.1%) and incontinence (11.6%) were infrequent (Table 1). Ileocolonoscopy was negative in 72 patients confirming IBS, 2 patients had diverticulosis, while 12 revealed findings of active endoscopic disease consistent with IBD, confirmed on pathology, 11 with CD and 1 with UC, as well as microscopic colitis (N=8), diverticulosis (N=1), ischemic colitis (N=2) and one solitary rectal ulcer. The overall sensitivity, specificity, PPV and NPV of POCUS were 83.0%, 100%, 100%, and 97.37%, respectively. In cases where POCUS was positive, POCUS predicted the severity of inflammation as seen on ileocolonscopy accurately with correlate findings of 90% (9/10 cases accurately predicted severity). The accuracy of POCUS for predicting IBD was much better than CRP, as the sensitivity of CRP was only 37.5%, specificity 76.2%. Wait time for endoscopy for patients with a positive POCUS was shorter with a median of 3.5 weeks, compared to 4 weeks for those with a negative POCUS.
Conclusions: Bedside POCUS is a useful triage tool, better than CRP in disease prediction, helpful to accurately detect the presence and severity of inflammation in the bowel and thus differentiate IBD from IBS. The detection of ileal disease was more accurate compared to colonic disease and future studies should be completed with addition of fecal calprotectin to optimize detection rates and overall accuracy.