Beyond the Scope: Advancing IBD Diagnosis and Management with Bedside Ultrasound

Introduction

Crohn’s disease (CD) and ulcerative colitis (UC) are chronic inflammatory bowel conditions characterised by periods of relapsing and remitting disease and progressive bowel damage. The complexity of IBD management and diagnosis lies in its heterogeneous presentation, unpredictable disease course, and the need for lifelong monitoring to prevent complications such as strictures, fistulas, and colorectal cancer.

The aims in management of inflammatory bowel disease include amelioration of patients’ symptoms, to promote endoscopic and histological remission in order to support long-term clinical remission and avoidance of IBD complications.1 Traditionally, this was achieved through regular surveillance endoscopy; the gold standard for assessing mucosal inflammation and guiding therapeutic decisions. Colonoscopy allows for direct visualisation of the intestinal mucosa, enabling biopsies for histopathological evaluation, which remains essential for confirming disease activity and dysplasia surveillance.2 However, it is not without its drawbacks. Endoscopy is an invasive, time-consuming, and costly procedure and creates a burden on ever-growing Irish waiting lists. It may also be associated with lower patient tolerability, anxiety and discomfort.3 In addition to colonoscopy, cross-sectional imaging modalities such as magnetic resonance enterography (MRE) and computed tomography (CT) are frequently employed to assess disease extent, complications, and extramural involvement. While these imaging techniques provide crucial insights, they can also be expensive, time-consuming, and, in the case of CT, expose patients to ionizing radiation.4

In recent years, intestinal or bowel ultrasound (IUS) has emerged as a valuable, non-invasive tool for evaluating IBD. Intestinal ultrasound utilises high-frequency sound waves to generate real-time images of the bowel wall and surrounding structures.5 IUS visualises all bowel wall layers (mucosa, submucosa, muscularis propria, serosa), enabling assessment of transmural inflammation, a hallmark of CD.

Unlike endoscopic procedures, IUS is non-invasive, requires no bowel preparation or sedation, and can be performed at the bedside. Key parameters assessed during IUS include:6

• Bowel Wall Thickness (BWT): Increased thickness (>3 mm in the small bowel and right colon, >4 mm in the left colon) often correlates with active inflammation
• Bowel Wall Hyperaemia using doppler ultrasound: marker of active inflammation
• Wall Stratification: Loss of the normal five-layer bowel wall structure suggests severe inflammation or fibrosis
• Surrounding lymphadenopathy and free fluid: can indicate more severe disease
• Complications associated with IBD: strictures, abscesses and fistula

Unlike colonoscopy, which primarily evaluates mucosal disease, IUS provides additional information on transmural inflammation and extramural complications, making it a complementary modality rather than a replacement.5 The integration of IUS into routine clinical practice has the potential to enhance patient care by providing immediate insights during consultations, thereby supporting a treat-to-target approach in IBD management.

Global Use

Numerous studies internationally, particularly those performed in the US and central Europe, have shown promising results for the introduction of IUS as a standard of care for IBD. The TRUST study was a large multicentre project conducted in over 45 German hospitals which found that IUS can be used to effectively monitor treatment response in patients with active CD.8

Whilst information can be extrapolated from these studies, it is potentially more useful to look at similar studies performed in the UK – slightly closer to home with similar patient cohorts and demographics to an Irish population. Literature of note includes the 2018 METRIC trial.17 In a cohort of 284 patients, the authors conclude both MRE and ultrasound have high sensitivity for detecting the presence of small bowel disease and both are valid first-line investigations in the assessment of IBD. In a further UK study in 2022, 260 patients were investigated via colonoscopy or MRE to assess lower gastrointestinal symptoms, IBD severity or clinical response to treatment.7 Patients were classified into either IUS-suitable or non-suitable based on clinical factors e.g. IBD patients without dysplasia surveillance or stricture dilatation. This study determined that 28% of endoscopy patients and 55% of MRE patients were deemed IUS suitable. The primary objective of this work was to assess the cost analysis of introducing IUS as a replacement for endoscopy/MRE for those deemed suitable. They concluded that a projected annual saving of £500,000 could be achieved with the implementation of a IUS integrated programme.

IUS in Ireland

Transabdominal ultrasound has been used as a modality for assessing IBD in central Europe; namely Germany and Italy for the preceding decades but has recently been utilised more in other European countries, Canada and the US via a centralised training programmed through the International Bowel Ultrasound Group (IBUS).8 The use of IUS in Ireland has gained acceptance and is now utilised across a small number of sites and will likely have a significant and positive impact on the future management of IBD and other lower GI conditions.9

Firstly, it can provide an accessible point of care investigation which can be performed by an IBD specialist in the outpatient setting. This has the potential to provide immediate treatment altering decisions in the case of an acute IBD flare, aid in endoscopic triage based on severity of findings and reduce the number of invasive tests in cases with a low pretest probability.7 Of note this may be particularly useful in ruling out non-inflammatory conditions such as irritable bowel syndrome and reducing endoscopy demand. Reassuring or normal ultrasound parameters could also be used to justify de-escalation of some immunosuppressants and therefore reduce medication exposure for patients. It also serves to escalate therapy in patients on biologics who have not fully responded to treatment and while not listed as a formal target in the updated STRIDE-II treat-to-target guidelines for IBD, IUS is recommended as an adjunct to endoscopy, cross-sectional imaging and biomarkers.a

By providing real time information at the patient’s bedside, IUS can have a positive effect on patient understanding of their own condition. Patients with IBD have been shown in the literature to potentially have a poor level of knowledge surrounding their condition and this is particularly prevalent in the pregnant population.11, 12 Misconceptions and false information can lead to detrimental actions such as stopping biologic medications, increasing the risk of a flare during pregnancy. Patients who have undergone point of care IUS have been shown to have a significant self-reported active disease reported better understanding of all aspects of their disease and disease symptoms and were more confident in their ability to make informed decisions about managing their disease.10 There are pregnancy-specific IBD clinics in Ireland and by introducing IUS, particularly in these clinics, we can help improve patient knowledge, provide reassurance and also prevents unnecessary radiation to pregnant individuals if further investigations are required. While there are limited studies investigating the use of IUS in pregnancy, the studies thus far have shown that IUS is a useful tool in pregnancy and can detect subclinical inflammation and stratify active inflammation in symptomatic patients.13

Lastly, despite improvements in biological therapy, surgical intervention is required in a significant proportion of patients with IBD.14 Long term inflammation increases the risk of developing strictures, abscesses and fistulae and may ultimately result in emergency surgery.15 While CT and MRI remain the gold standard for postoperative assessment, IUS offers a rapid, bedside, and radiation- and bowel preparation-free alternative for early detection of postoperative recurrence. Furthermore, this use of IUS, in combination with faecal calprotectin, has been proven to be a valid and reliable tool for monitoring postoperative patients with CD, predicting the risk of postoperative recurrence, allowing for earlier escalation or reinstatement of biologics.16

Limitations

With every imaging modality, there are limitations. CT can provide high resolution images of bowel and extraintestinal complications whilst also being readily available particularly in emergency situations such as suspected perforation.14 As mentioned, CT is associated with radiation exposure which is a concern for the predominantly young demographic of patients who require frequent scanning. MRE can provide a radiation free alternative to CT and can provide high diagnostic accuracy for detecting the presence and activity of CD with reasonable interobserver agreement.4 This is in direct comparison to IUS which has the potential to be limited by operator skill and inter-operator variability. Patient preference and experience is also a crucial role in determining a choice of modality. The METRIC trial found that while the overall burden of MRE was relatively low, it was still notably higher than that of IUS and patient willingness to undergo repeat testing was less when compared to IUS.9

In conclusion, the field of inflammatory bowel disease continues to evolve and the role of IUS is becoming increasingly significant due to its non-invasive nature, real-time assessment and radiation-free advantages. While traditional imaging modalities such as MRI, CT, and endoscopy remain important in IBD diagnosis and management, IUS offers a cost-effective, accessible, and patient-friendly alternative, particularly for disease monitoring and treatment response evaluation. Increased training, investment, awareness of IUS’s diagnostic accuracy and patient benefits will see it become a key component in Ireland’s IBD care strategy. Moving forward, a multimodal approach combining endoscopy, cross-sectional imaging, and IUS will likely optimise disease management, ensuring patients receive timely and effective care.

References available on request

Written by Dr Ella Patchett and Dr Karl Hazel – Department of Gastroenterology, Connolly Hospital Blanchardstown

Read more Clinical Features

Read March HPN