Background: Crohn’s disease [CD] is frequently associated with the development of strictures and penetrating complications. Intestinal ultrasound [IUS] is a non-invasive imaging modality ideal for point-of-care assessment. In this systematic review and meta-analysis we provide a current overview on the diagnostic accuracy of IUS and its advanced modalities in the detection of intra-abdominal complications in CD compared to endoscopy, cross-sectional imaging, surgery, and pathology. Method: We conducted a literature search for studies describing the diagnostic accuracy of IUS in adult patients with CD-related intra-abdominal complications. Quality of the included studies was assessed with the QUADAS-2 tool. Meta-analysis was performed for both conventional IUS [B-mode] and oral contrast IUS [SICUS]. Results: Of the 1498 studies we identified, 68 were included in this review and 23 studies [3863 patients] were used for the meta-analysis. Pooled sensitivities and specificities for strictures, inflammatory masses, and fistulas by B-mode IUS were 0.81 and 0.90, 0.87 [sensitivities] and 0.95, and 0.67 and 0.97 [specificities], respectively. Pooled overall log diagnostic odds ratios were 3.56, 3.97 and 3.84, respectively. Pooled sensitivity and specificity of SICUS were 0.94 and 0.95, 0.91 and 0.97 [sensitivities], and 0.90 and 0.94 [specificities], respectively. The pooled overall log diagnostic odds ratios of SICUS were 4.51, 5.46, and 4.80, respectively. Conclusion: IUS is accurate for the diagnosis of intra-abdominal complications in CD. As a non-invasive, point-of-care modality, IUS is recommended as the first-line imaging tool if there is a suspicion of CD-related intra-abdominal complications.

Although the number of therapeutic options for the treatment of inflammatory bowel disease (IBD) has increased in recent years, patients suffer from decreased quality of life due to non-response or loss of response to the currently available treatments. An increased understanding of the disease’s etiology could provide novel insights for treatment strategies in IBD. Lymphatic system components are generally linked to immune responses and presumably related to inflammatory diseases pathophysiology. This review aims to summarize findings on immune-mediated mechanisms in lymphoid tissues linked with IBD pathogenesis and (potential) novel treatments. Enhanced innate and adaptive immune responses were observed in mesenteric lymph nodes (MLNs) and other lymphoid structures, such as Peyer’s patches, in patients with IBD and in animal models. Furthermore, the phenomenon of lymphatic obstruction in the form of granulomas in MLNs and lymphatic vessels correlates with disease activity. There is also evidence that abnormalities in the lymphatic stromal components and lymph node microbiome are common in IBD and could be exploited therapeutically. Finally, novel agents targeting lymphocyte trafficking have been added to the treatment armamentarium in the field of IBD. Overall, gut-associated lymphoid tissue plays a key role in IBD immunopathogenesis, which could offer novel therapeutic targets.

Background and Aims: The submucosa is the most responsive bowel wall layer on intestinal ultrasound (IUS) when assessing treatment response in ulcerative colitis (UC). Submucosal thickening with hyper-echogenicity is observed. This study aimed to quantify echogenicity and understand transmural changes in UC. Methods: In total, 118 patients were studied in two cohorts. Cohort 1 included colectomy patients: 19 UC patients and 52 controls without inflammatory bowel disease. Cohort 2 included 47 UC patients in a prospective cohort starting anti-inflammatory treatment. In Cohort 1, submucosal inflammation, and fat and collagen deposition were scored by two pathologists using a semi-quantitative scale (0–3). For UC patients in Cohort 1, histopathology and IUS of the sigmoid were location matched. Relative submucosal echogenicity (RSE) was assessed, quantified in grayscale values. In Cohort 2, baseline sigmoid RSE was compared between endoscopic responders (≥1 point decrease in endoscopic Mayo score after 8–26 weeks) and non-responders. Results: In all colectomized UC patients with preserved wall layer stratification (n = 12, 63%), submucosal fat (score ≥1) was present; in those with loss of stratification (n = 7, 37%), fat was absent (score = 0). RSE was higher when fat was present [95.5 (IQR 86.5–116.9) vs 8.1 (IQR 5.8–23.0) grayscale values, P < .001], with no significant differences for inflammation and collagen. In Cohort 2, RSE was higher in non-responders (n = 17) compared to responders (137.1 ± 50.9 vs 88.3 ± 49.6 grayscale values, P = .003). An RSE of >108 grayscale values predicted non-response [OR: 0.07 (95% CI: 0.01–0.44), P = .004]. Conclusion: Submucosal hyper-echogenicity on IUS indicates fat deposition and predicts non-response in UC.

Background & Aims: Endoscopic healing (EH) is recognized as a long-term treatment goal for patients with ulcerative colitis (UC). We investigated whether transmural healing (TH) in UC as assessed by intestinal ultrasound (IUS) is associated with improved outcomes compared to EH alone. Methods: We performed a retrospective study in a tertiary center on patients with left-sided or extensive UC on stable maintenance treatment who had EH [Mayo Endoscopic Subscore (MES) ≤1) and an IUS performed within 6 months of an endoscopy with no treatment alterations between IUS and endoscopy. TH was defined as bowel wall thickness (BWT) <3 mm. The primary outcome was relapse-free survival in patients with and without TH. Results: A total of 61 patients (MES 0: 44.3%; MES 1: 55.7%) with a median follow-up of 20 months were included. On IUS, 72% of patients had TH. Twenty-three patients had a relapse (first-year relapse risk: TH: 7.5% vs no TH: 29.4%, P = .004; MES 0: 3.7% vs MES 1: 20.8%, P = .059). In multivariate Cox regression, female gender [hazard ratio (HR), 2.63; 95% CI 1.05–6.58; P = .039], two or more previous advance therapies (HR, 4.06; 95% CI 1.08–15.28; P = 0.038), and non-TH (HR, 3.99; 95% CI 1.31–12.20; P = .015) were associated with a relapse whereas EH level (MES 0 vs MES 1) was not an associated factor (HR, 1.06; 95% CI 0.32–3.55; P = .924) Conclusions: In UC patients TH is associated with lower relapse risk compared to EH alone. These findings imply that IUS is a non-invasive, low-cost alternative to endoscopy for stratifying UC patients for risk of relapse.

Introduction: Intestinal ultrasound (IUS) is a promising tool for predicting treatment response in inflammatory bowel disease (IBD). We aimed to systematically review existing literature on the predictive value of IUS for treatment response. Methods: A literature search was performed until May 2025. We included articles assessing treatment response in IBD using IUS. Data were analyzed separately for Crohn’s Disease (CD), ulcerative colitis (UC) and acute severe ulcerative colitis (ASUC). Pooled data analysis was performed for bowel wall thickness (BWT) in CD patients starting anti-TNF (tumor necrosis factor). Results: In total, 31 articles were included (18 CD, 9 UC, and 4 ASUC). In 8/10 CD studies, IUS at week 4-8 could distinguish future responders, with BWT change ranging from −43% to −14.6% in responders vs. −14% to + 2% in nonresponders. In the pooled data analysis of anti-TNF-treated CD patients (n = 236) a 23% decrease from baseline at week 4-8 (area under the receiver operating characteristic curve [AUROC] 0.82) and 27% decrease at week 12-16 (AUROC 0.78) could predict future response. In 2/2 UC studies, IUS after 4-8 weeks could predict future endoscopic remission vs. non-remission with a decrease in BWT ranging from −55% to −49% vs. −38% to −17% respectively. In ASUC, change in BWT after 1-3 days could predict need for salvage therapy (−34% vs. −10%). Conclusions: Intestinal ultrasound predicts response at an early stage after treatment initiation, both in CD as well as in UC. In anti-TNF-treated CD patients, 23% and 27% decrease in BWT after 4-8 weeks and 12-16 weeks of treatment initiation predicts outcomes.

Background and Aims: Perianal complications such as fistulas and abscesses are common in Crohn’s disease (CD) and contribute to significant morbidity. Transperineal ultrasonography (TPUS) has emerged as a non-invasive and accurate method for perianal fistulizing CD (pfCD). This review evaluates the diagnostic accuracy of TPUS compared with magnetic resonance imaging (MRI), transrectal ultrasonography (TRUS), and examination under anesthesia (EUA) for detecting and classifying perianal fistulas and abscesses. Methods: A comprehensive literature search was conducted across multiple databases through January 2025 to identify studies evaluating TPUS accuracy in detecting perianal fistulas and abscesses compared with MRI, TRUS, or EUA as the reference standard. Meta-analysis was performed to assess TPUS accuracy for fistula detection (FD), fistula classification (FC), internal opening (IO) detection, and abscess detection (AD). The Quality Assessment of Diagnostic Accuracy Studies-2 tool was used to evaluate risk of bias. Results: Of 1059 studies identified, 29 were included in this review. Pooled sensitivities for FD (18 studies, 1474 patients), FC (11 studies, 585 patients), IO detection (six studies, 481 patients), and AD (16 studies, 1276 patients) were 97.5%, 80.3%, 89.6%, and 93.5% respectively while pooled specificities for FD, IO detection, and AD were 69.0%, 66.3%, and 94.5% respectively. The overall TPUS accuracy for FD, FC, IO detection, and AD was 88.0%, 88.6%, 77.8%, and 91.8% respectively. Subgroup analysis on CD patients showed an accuracy of 86.4%, 87.6%, and 83.3% for FD, FC, and AD respectively. Conclusions: TPUS demonstrates high accuracy in detecting perianal fistulas and abscesses, supporting its use as a non-invasive, first-line diagnostic tool.