Inflammatory Bowel Disease (IBD), which includes Crohn’s disease (CD) and ulcerative colitis (UC), is a chronic, relapsing inflammatory condition of the gastrointestinal tract with a significant global burden [1]. The pathogenesis involves genetic susceptibility, environmental factors, immune dysregulation, and gut microbiota alterations [2]. Accurate and timely assessment of disease activity is vital for guiding treatment decisions and improving outcomes [3].

While colonoscopy is considered the gold standard for evaluating mucosal inflammation and disease extent, it is invasive, costly, and carries risks such as perforation and sedation-related complications [4]. Therefore, there is growing interest in non-invasive, point-of-care imaging tools like bowel ultrasound (BUS) that offer real-time assessment of intestinal inflammation [5].

Recent studies have shown that BUS can detect bowel wall thickening, hypervascularity, loss of wall stratification, and complications like strictures and fistulas, particularly in CD [6]. For UC, although confined to the mucosa, increased bowel wall thickness and hyperemia have also been visualized using ultrasound [7]. Moreover, BUS offers advantages such as repeatability, lack of ionizing radiation, and immediate results, making it ideal for disease monitoring.

Despite these benefits, BUS remains underutilized in clinical practice, partly due to variability in operator expertise and limited data comparing it with colonoscopy or clinical indices. There is a need for more real-world data to validate its diagnostic performance and clinical utility.

A total of 120 adult patients (aged 18–65 years) with a confirmed diagnosis of IBD (either CD or UC) based on clinical, endoscopic, histological, and radiological criteria were included.

Inclusion Criteria:

• Confirmed diagnosis of CD or UC
• Willingness to undergo colonoscopy and BUS within 72 hours
• Informed consent

Exclusion Criteria:

• Previous bowel surgery
• Pregnancy
• Uncooperative patients
• Incomplete colonoscopy due to poor bowel preparation

Ultrasound Examination:

All BUS examinations were performed by a single experienced radiologist using a high-frequency linear probe (7–12 MHz) in a fasting state. Parameters recorded included:

• Bowel Wall Thickness (BWT): >3 mm considered abnormal
• Limberg Score (vascularity grading via Doppler)
• Bowel wall stratification (normal, blurred, or absent)
• Detection of complications: strictures, fistulas, abscesses

Colonoscopy and Disease Activity Scores:
Colonoscopy was performed by a blinded endoscopist. Disease activity was scored using:

• Harvey-Bradshaw Index (HBI) for CD
• Mayo Score for UC

Statistical Analysis:

Data were analyzed using SPSS v26. Continuous variables were expressed as mean ± standard deviation (SD) and compared using t-tests or ANOVA. Categorical variables were compared using chi-square tests. Correlation was assessed using Pearson’s correlation coefficient (r), and agreement was measured using Cohen’s kappa (κ). A p-value <0.05 was considered statistically significant.

Demographic and Clinical Data:

Of 120 IBD patients, 68 had CD and 52 had UC. The mean age was 37.4 ± 11.6 years, with 56.7% males. Table 1 presents the baseline characteristics.

Bowel Wall Thickness and Disease Activity:

In CD patients, increased BWT (>3 mm) was found in 83.8% of those with moderate-to-severe disease (HBI >8). The mean BWT in active CD was 5.8 ± 1.4 mm vs. 2.9 ± 0.6 mm in remission (p < 0.001). For UC patients, mean BWT in active disease was 4.2 ± 0.9 mm compared to 2.5 ± 0.5 mm in remission (p = 0.003).

Vascularity and Wall Stratification:

A Limberg score ≥2 was seen in 71.2% of active CD patients. Loss of wall stratification correlated with higher disease activity (p < 0.01).

Correlation with Disease Activity Indices:

Strong positive correlation was observed between BWT and HBI for CD (r = 0.74, p < 0.001), and between BWT and Mayo score for UC (r = 0.61, p = 0.002).

Complications Detected by BUS:

BUS detected 21 strictures, 7 fistulas, and 3 abscesses in CD patients. All findings were later confirmed on colonoscopy or MRI. In UC, no transmural complications were identified.

Diagnostic Accuracy:

Compared with colonoscopy, BUS showed:

• Sensitivity: 89.4%
• Specificity: 84.1%
• Positive Predictive Value: 91.8%
• Negative Predictive Value: 80.0%
• Kappa (κ) agreement: 0.76 (substantial agreement) (Table 1-5)

Table 1: Baseline Characteristics of Study Population

Table 2: Bowel Wall Thickness (BWT) and Disease Activity

Table 3: Correlation of BUS Parameters with Disease Activity Scores

Table 4: Complications Detected by BUS in CD Patients

Table 5: Diagnostic Accuracy of BUS Compared to Colonoscopy

This study supports the growing body of evidence that bowel ultrasound is a valuable diagnostic and monitoring tool for IBD. The strong correlation between BWT and disease activity in both CD and UC aligns with findings from Calabrese et al., who reported similar diagnostic performance of BUS in monitoring mucosal inflammation [8].

In CD patients, ultrasound's ability to detect complications such as strictures and fistulas is particularly beneficial. According to Novak et al., BUS demonstrated 85–90% sensitivity for detecting strictures and 70–75% for fistulas [9], comparable to our findings.

For UC, although the disease is limited to the mucosa, increased BWT and hypervascularity were reliably detected in active disease, echoing the observations of Ripollés et al. [10]. The correlation between BUS parameters and clinical indices (HBI, Mayo score) further validates its utility.

However, the performance of BUS can be influenced by operator experience, patient body habitus, and bowel gas interference [11]. Despite these limitations, BUS remains a non-invasive, rapid, and radiation-free imaging modality.

Comparatively, while colonoscopy allows direct mucosal visualization and biopsy, its invasiveness limits frequent usage. The integration of BUS for routine follow-up can reduce the dependency on endoscopy and improve patient comfort.

Our study is limited by its single-center design and the operator dependency of ultrasound. Future multicentric studies with larger cohorts and standardized BUS protocols are warranted.

Bowel ultrasound is a reliable, non-invasive imaging tool for assessing disease activity and detecting complications in IBD. It shows high correlation and agreement with colonoscopy and clinical indices. Incorporating BUS into routine IBD care may enhance disease monitoring, reduce reliance on invasive procedures, and improve patient compliance.

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