Differential diagnosis of inflammatory bowel diseases by endoscopic ultrasound

Abstract

Rationale: At present, there is no established standard for the differential diagnosis of Crohn's disease (CD) and ulcerative colitis (UC). Five to 15% of the patients have clinical, endoscopic, morphological, and radiological signs both of UC and CD and are therefore diagnosed with indeterminate colitis. However, the timely and correct diagnosis is essential for the choice of treatment strategy. Aim: To evaluate the potential of endoscopic ultrasound examination (EUS) for the differential diagnosis of UC and CD and to identify the most pathognomonic criteria for each of the disorders. Materials and methods: This was a prospective single center controlled study including 50 in-patients who were treated in the Department of Gastroenterology for inflammatory bowel disease (IBD) exacerbation. The inclusion criteria were an established diagnosis of IBD, absence of strictures, colon tumors, and infectious diseases. The control group consisted of 15 patients without IBD. In all patients, colon EUS with a radial ultrasound sensor and measurement of the intestinal wall thickness, assessment of the degree of intestinal wall vascularization by color Doppler mapping and measurement of the wall density by compression elastography were performed. Results: From 50 patients of the study group, 28 (16 men and 12 women aged 18 to 49 years) had CD of the colon and 22 (8 men and 14 women aged 22 to 60 years) had total UC. In CD, the colon wall thickness was 2-fold higher than in the control group (5.66 0.36 vs 2.62 0.11; р 0.001) and 1.5-fold higher than in the UC patients (5.66 0.36 vs 3.96 0.13; p = 0.002). In UC, the intestinal wall was thickened mainly due to its mucosal and submucosal layers (in 82% of the cases, р 0.001 compared to that in the CD patients; diagnostic sensitivity 82%, specificity 93%). In CD, transmural thickening of the intestinal wall was more common (in 68% of the cases, p 0.001 compared to that in UC; sensitivity 68%, specificity 91%), as differentiation of the intestinal wall layers was absent (in 68% of the cases, p 0.001 compared to UC, sensitivity 68%, specificity 100%). The intestinal wall in most cases of UC was less well vascularized that in the control group (54.6% of the cases, p 0.001), whereas in CD, on the contrary, the vascularization was increased (71.4% of the cases, р 0.001); the sensitivity and specificity of this parameter being 54.6 and 82%, for UC vs 71.4 and 77.3% for CD, respectively). Compression elastometry showed that in CD, type 2 staining (E. Ueno classification) was more frequent (45%) compared to UC (22%) and the control group (6%; p = 0.002), which indicates a more dense structure of the intestinal wall in CD patients. Conclusion: The differences in the intestinal wall structure (its thickness, density and degree of vascularization) identified by EUS UC and CD can be the differential diagnostic criteria between these diseases.