Significance of abdominal ultrasound in inflammatory bowel disease

Transabdominal ultrasound is most commonly used to examine the liver, hepatobiliary-pancreatic and urogenital tract. Its use for imaging the intestinal tract is less well established and has been considered more difficult in the past. Improvements in technology and increasing experience with sonographic findings in a variety of intestinal diseases including inflammatory bowel disease (IBD), however, have contributed to firmly establishing the role of ultrasound as a clinically important, non-invasive and widely available imaging modality. In addition, newer techniques such as harmonic imaging and contrast-enhanced ultrasound have recently gained attention. Transabdominal ultrasound is clinically useful in the initial diagnosis of IBD by evaluating bowel wall thickness and surrounding structures including peri-intestinal inflammatory reaction, extent and localization of involved bowel segments and detection of extraluminal complications such as fistula, abscesses, carcinoma and ileus. Transabdominal ultrasound is currently accepted as a clinically important first-line tool in assessing patients with Crohn's disease irrespective of their clinical symptoms and/or disease activity. It helps to better characterize the course of the disease in individual patients and can guide therapeutic decisions. The topic of this review is to provide an updated overview of the role of transabdominal ultrasound in IBD including Crohn's disease, ulcerative colitis, tuberculosis and neutropenic colitis while summarizing the results of recent studies with special reference to sensitivity/specificity in detecting the disease and sonomorphologic features to evaluate disease activity and its luminal and extraluminal complications.