Ultrasound of the bowel is routine in evaluation of adults and children with inflammatory bowel disease (IBD) in Europe, but is only recently emerging as an evaluation technique in North America, according to an article in the May issue of the American Journal of Roentgenology.
Growing attention on radiation safety and awareness poses an opportunity to replace radiation-free modalities, like ultrasound, with radiation-dependent modalities, like fluoroscopy and computed tomography (CT). Ultrasound, which requires minimal preparation and no sedation, makes it an appealing modality for the pediatric population. While there are clinical limitations to bowel ultrasound, the AJR article states that an additional challenge is the need for specialized training and experience to perform and interpret the exams.
The authors of the study by Anupindi et al introduced a dedicated nonemergent bowel ultrasound in the Department of Radiology at The Children’s Hospital of Philadelphia at University of Pennsylvania Perelman School of medicine approximately three years ago. Since then, they have implemented a tailored ultrasound technique and expanded indications for bowel ultrasound to include detection and diagnosis of necrotizing enterocolitis (NEC), Henoch-Schönlein purpura (HSP), foreign bodies and polyps, in addition to evaluating children with IBD.
Ultrasound can provide information beyond radiographic evaluation for NEC, a common and important case of morbidity and mortality in premature infants in the neonatal ICU setting, the authors wrote. A 2005 article in Radiology stated the diagnostic performance of ultrasound for the diagnosis of NEC has sensitivity of 100 percent, specificity of 90 percent, positive predictive value (PPV) of 83 percent and negative predictive value (NPV) of 100 percent.
While evidence-based data on the performance of ultrasound in the diagnosis of HSP, an autoimmune vasculitis that may affect the bowel, skin, joints and kidneys, a report in the Journal of Pediatric Gastroenterology and Nutrition found when HSP involves the gastrointestinal tract, ultrasound diagnosis has a sensitivity of 83 percent, specificity of 100 percent, PPV of 100 percent and NPV of 54 percent.
Since not all foreign bodies are detectable on conventional radiography, the current modality of choice in evaluating foreign bodies, ultrasounds can provide an additional option, the authors wrote. The diagnostic performance of ultrasound use for evaluating foreign bodies is unknown, but the authors cite several studies in which foreign bodies ranging from sponges to smuggled drug containers have been detected on ultrasound.
A recent study in Ultrasound in Medicine and Biology showed excellent correlation between polyp detection on ultrasound with surgery and colonoscopy, although literature on the diagnostic performance of ultrasound in the detection of polyps is limited, the authors wrote.
The authors conclude that bowel ultrasound has full potential in evaluating a wide variety of conditions, and familiarity with compression technique and interpretation of exams enable bowel ultrasound to provide a unique and effective evaluation of the bowel without use of ionizing radiation.