and in early identifying intra-abdominal complications, selleck such as abscesses, fistulae and strictures[41-44]. The reported sensitivity of US in detecting CD strictures approximately is 74%-80%[41]. US can also aid differentiate between fibrotic and inflammatory strictures. An increased Colour-Doppler signal in the stenosis is suggestive of activity, while poor vascularity of the bowel wall, an adjacent loops�� retraction and a pre-stenotic bowel segment distension are suggestive of fibrotic stenosis (Figure (Figure55)[31]. Figure 5 Longitudinal section of a distal ileal loop showing stiffness, mural thickening (arrowhead), lumen narrowing (arrow) and mild dilatation of the pre-stenotic segment (asterisk), suggesting a fibrotic nature of the stenosis.

Some challenges about US still remain: US strongly relies on the operator��s experience and skill more than other imaging modalities, and it requires an high resolution equipment. Moreover, even in expert hands, US may result in false positive findings[34]: thickening of the intestinal wall is not specific for CD, also being present in infectious, neoplastic and other inflammatory conditions. US may also provide false negative results[38,42], for example in obese patients or when CD is characterized by only superficial lesions, like isolated aphthous ulcers and mucosal erosions, or in presence of intestinal gas that make hardly visible the bowel wall, particularly the proximal ones. Small Intestine Contrast US (SICUS). Some studies in adults have demonstrated that the so called SICUS, enables to overcome limits of standard US.

Dissociation of intestinal overlapping loops and visualization of the entire SB, from the Treitz angle to the ileo-cecal valve, are obtained by distending the SB with an oral anechoic non-absorbable contrast solution (iso-osmolar polyethylene glycol)[36]. Briefly, US examination in performed after the ingestion of the oral contrast solution, that fill in the loops, and the administration of the intravenous (iv) contrast. Unfortunately the procedure is time consuming, requiring in some cases more than 2 hours. Pallotta et al[28] studied 148 patients, 57 with a known diagnosis of CD, showing SICUS to be more sensitive and specific (94% and 98%, respectively) than conventional US (57% and 100% respectively) in assessing SB lesions.

The use of an oral contrast agent can significantly improve US sensitivity, approximately of 90% (Figure (Figure6)6) and of over 75% for a single and multiple SB stenosis, respectively[42]. Figure 6 The oral anechoic contrast solution, (polyethylene glycol), allows a better definition of lumen narrowing (arrow) and pre-stenotic dilatation (asterisk) as well as a more accurate GSK-3 measurement of the length of the stenosis. Small intestine contrast ultrasonography … SICUS can make a dynamic evaluation of the affected segment differentiating between inflammatory and fibrotic stenosis.