Non-Invasive vs. Invasive Markers in Ulcerative Colitis: A Systematic Review of Intestinal Ultrasound, Biopsy, and Faecal Calprotectin

Accurate assessment of histological remission is a critical goal in the management of ulcerative colitis (UC); however, routine evaluation is hindered by the invasiveness of endoscopy and biopsy. Non-invasive alternatives like intestinal ultrasound (IUS) and faecal calprotectin (FC) show promise for monitoring mucosal inflammation, though their ability to predict histological healing remains underexplored. This systematic review and meta-analysis aimed to evaluate the diagnostic accuracy of IUS, FC, and their combined use for detecting histologic remission in patients with UC. A comprehensive literature search identified two eligible studies comprising 72 patients. Pooled estimates for IUS demonstrated high sensitivity (0.84, 95% CI: 0.35–0.98) but variable specificity (0.78, 95% CI: 0.08–0.99), while FC alone exhibited high sensitivity (0.85, 95% CI: 0.72–0.92) with moderate specificity (0.60, 95% CI: 0.38–0.79). Notably, only one study assessed the combined diagnostic approach, reporting superior performance with sensitivity and specificity of 0.88 and 0.80, respectively. The certainty of the evidence was rated as moderate. These exploratory findings suggest that a multimodal, non-invasive approach combining IUS and FC may improve diagnostic accuracy in detecting histological remission in UC, potentially reducing reliance on invasive procedures. However, given the limited number of studies included and the high degree of heterogeneity, these results should be interpreted with caution. Further large-scale, methodologically robust studies are needed to validate these preliminary findings and establish standardized diagnostic protocols.