Prognostic role of intestinal ultrasound in Crohn's disease

Abstract

The majority of patients affected by Crohn's disease (CD) develop a chronic condition with persistent inflammation and relapses that may cause progressive and irreversible damage to the bowel, resulting in stricturing or penetrating complications in around 50% of patients during the natural history of the disease. Surgery is frequently needed to treat complicated disease when pharmacological therapy failes, with a high risk of repeated operations in time. Intestinal ultrasound (IUS), a non-invasive, cost-effective, radiation free and reproducible method for the diagnosis and follow-up of CD, in expert hands, allow a precise assessment of all the disease manifestations: Bowel characteristics, retrodilation, wrapping fat, fistulas and abscesses. Moreover, IUS is able to assess bowel wall thickness, bowel wall stratification (echo-pattern), vascularization and elasticity, as well as mesenteric hypertrophy, lymph-nodes and mesenteric blood flow. Its role in the disease evaluation and behaviour description is well assessed in literature, but less is known about the potential space of IUS as predictor of prognostic factors suggesting response to a medical treatment or postoperative recurrence. The availability of a low cost exam as IUS, able to recognize which patients are more likely to respond to a specific therapy and which patients are at high risk of surgery or complications, could be a very useful instrument in the hands of IBD physician. The aim of this review is to present current evidence about the prognostic role that IUS can show in predicting response to treatment, disease progression, risk of surgery and risk of post-surgical recurrence in CD.

Keywords: Bowel wall thickness; Crohn’s disease; Intestinal surgery; Intestinal ultrasound; Postoperative recurrence; Remission.

Figure 1

Intestinal ultrasound assess several features of the bowel wall and surrounding tissue. A: Bowel wall thickness should be measured perpendicular to the anterior wall of the bowel (or where it is better visible) avoiding haustrations and mucosal folds. The cursor/calipers should be placed at the end of the interface echo between the serosa and the proper muscle to the start of the interface echo between the lumen and the mucosa; B: Bowel wall stratification. The wall layers in case of active disease may appear focally or extensively disrupted (disrupted or hypoechoic echo pattern); C: Bowel wall vascularity. Bowel wall vascularity can be determined both by colour Doppler or power Doppler signal at the level of the most thickened segments, using special presets optimized for slow flow detection; D: Mesenteric hypertrophy. Mesenteric hypertrophy also called fat wrapping or creeping fat appears on ultrasound (US) as hyperechoic tissue or “mass effect” encircling the diseased bowel; E: Lymphnodes. Enlarged inflammatory mesenteric lymph nodes related to Crohn’s disease are usually described at US as oval or elongated with lesser diameter > 5 mm and seem to be correlated with young age, early disease, or disease with shorter duration, and with the presence of fistulae and abscesses.