Global IBD experts, including leading Australian gastroenterologists, have developed the first consensus guidance on defining and monitoring small bowel strictures in Crohn’s disease on intestinal ultrasound.

Writing in the Lancet Gastroenterology and Hepatology [link here], the international researchers noted that definitions of strictures had been developed for CT enterography and magnetic resonance enterography via expert recommendations, however there was no similar guidance available for point-­of-­care intestinal ultrasound.

This was despite intestinal ultrasound being a comparable modality, which was growing in use worldwide to manage Crohn’s disease as a non­invasive, well tolerated, cost effective, and easily repeatable alternative, they added.

The expert panel informing the recommendations consisted of 13 gastroenterologists, seven radiologists and two patient representatives, who rated hundreds of statements on stricturing definitions and treatment responses according to their level of appropriateness.

The panel agreed that the definition of naive and anastomotic small bowel Crohn’s disease strictures on intestinal ultrasound should match the criteria for CT enterography and magnetic resonance enterography and include the same three features: bowel wall thickness, luminal narrowing and pre-stenotic dilation.

Bowel wall thickness was defined as being more than 3 mm, and luminal narrowing was defined as either a luminal diameter reduction of more than 50% in the narrowest area and relative to a normal adjacent bowel loop, or a luminal diameter of less than 1 cm. Pre-stenotic dilation was defined as more than 2.5 cm or an increase in bowel diameter relative to a normal adjacent bowel loop.

None of the current adjunctive tools or novel intestinal ultrasound techniques, such as intravenous contrast, and strain or shear wave elastography were accurate enough to differentiate the inflammatory and fibrotic components of strictures.

The consensus statements indicated that successful anti-­inflammatory stricture treatment would improve stricture length, bowel wall thickness, luminal narrowing, pre­-stenotic dilation, motility abnormalities, loss of bowel wall layer stratification, mesenteric inflammatory fat, penetrating disease, ulceration, mural or peri­enteric hyperaemia and comb sign on intestinal ultrasound.

Successful anti­fibrotic treatment would improve stricture length, bowel wall thickness, luminal narrowing, pre-­stenotic dilation, and motility abnormali­ties.

Features to detect anti­fibrotic treatment failure on intestinal ultrasound included stricture length, bowel wall thickness, luminal narrowing, pre-stenotic dilation, motility abnormalities, ulceration, and mural or peri­enteric hyperaemia.

The experts, which included Associate Professor Jakob Begun from the University of Queensland and Associate Professor Britt Christensen from University of Melbourne, also defined grading hyperaemia, inflammatory fat, wall stratification, intestinal ultrasound machine technical parameters, and image acquisition.

They said their statements provided a framework to formally develop and validate an intestinal ultrasound index for future clinical trials of stricturing Crohn’s disease.