Sonography for Surveillance of Patients With Crohn Disease

rohn disease is a chronic inflammatory condition of the bowel characterized by periods of quiescence and inflammatory activity or “disease flares.” Although genetic factors, dysbiosis, and altered immunity are implicated in inflammatory bowel disease, the etiology is unknown.1 The peak age of onset is early in life, between 15 and 40 years, thus affecting patients during their most productive years with potential for substantial social and personal costs.2,3 Crohn disease tends to complicate over time, with the development of fistulas and fibrostenotic lesions. As a result, surgical intervention rates in the prebiologic era were high.4 However, early and appropriate medical management can alter the course of this disease, with reductions in surgical rates and hospitalization.3,5 Detection of disease activity through objective monitoring is key to changing the long-term outcome and disability. Monitoring clinical symptoms alone is inadequate: the presence or absence of these does not reflect disease activity. Routine endoscopic monitoring is also not feasible because it is an invasive examination with associated risks and the need for preparation. Computed tomography (CT) with dedicated small-bowel imaging or enterography has been the modality of choice to date, but there is mounting evidence questioning its safety and repeatability, given ionizing radiation exposure in these young patients.6,7 Magnetic resonance imaging (MRI) is a radiation-free alternative and has also been shown to be effective in detection of inflammatory activity.8 However, this modality is expensive, and the lack of access precludes routine use. Transabdominal sonography is a highly effective modality for detecting inflammatory activity in Crohn disease, equal to that of CT or MRI.9,10 Sonography is particularly sensitive in detecting ileocecal Crohn disease compared to the reference standard ileocolonoscopy and thus is a useful initial screening tool to aid in diagnosis.11 Postoperative Crohn disease recurrence is also reliably detected with sonography, a suggested surrogate for endoscopic evaluation.12,13 It is an effective modality in the detection of complications such as strictures, fistulas, and abscesses, with surgical pathologic confirmation showing sensitivity as high as 100%.14 Although there are little existing data on the utility of any transmural modality in routine monitoring of disease activity in asymptomatic patients, there is a move toward more frequent observation, given the disconnect between symptoms and disease. Sonography is a superb modality for monitoring stable patients with a Kerri L. Novak, MSc, MD, FRCPC, Stephanie R. Wilson, MD, FRCPC