Intestinal ultrasound has a good accuracy in the diagnosis of Crohn's disease, as well as in the assessment of disease activity, extent, and evaluating disease-related complications, namely strictures, fistulae, and abscesses. Even though not fully validated, several scores have been developed to assess disease activity using ultrasound. Importantly, intestinal ultrasound can also be used to assess response to treatment. Changes in ultrasonographic parameters are observed as early as 4 weeks after treatment initiation and persist during short- and long-term follow-up. Additionally, Crohn's disease patients with no ultrasound improvement seem to be at a higher risk of therapy intensification, need for steroids, hospitalisation, or even surgery. Similarly to Crohn's disease, intestinal ultrasound has a good performance in the diagnosis, activity, and disease extent assessment in ulcerative colitis patients. In fact, in patients with severe acute colitis, higher bowel wall thickness at admission is associated with the need for salvage therapy and the absence of a significant decrease in this parameter may predict the need for colectomy. Short-term data also evidence the role of intestinal ultrasound in evaluating therapy response, with ultrasound changes observed after 2 weeks of treatment and significant improvement after 12 weeks of follow-up in ulcerative colitis.

1. Diagnostics in Inflammatory
Bowel Disease (IBD):
Ultrasound
Dr Abhineet Dey
Silchar Medical College & Hospital (SMCH)

2. World Journal of Gastroenterology Volume 17, Issue 27 / July 2021
Strobel, D., Goertz, R. S., & Bernatik,T. (2011). Diagnostics in inflammatory bowel disease: ultrasound.World journal of gastroenterology,
17(27), 3192–3197. https://doi.org/10.3748/wjg.v17.i27.3192

3. Introduction
Diagnosis of chronic inflammatory bowel diseases (IBD) is based on a combination of clinical symptoms,
laboratory tests and imaging data.

4. Introduction
 Imaging of the morphological characteristics of IBD includes the assessment of mucosal alterations,
transmural involvement and extraintestinal manifestations. No single imaging technique serves as a
diagnostic gold standard to encompass all disease manifestations.
 Ultrasound, computed tomography (CT) or magnetic resonance imaging (MRI) allow cross-sectional
imaging of the transmural alterations and extraintestinal manifestations.
 While in the USA the technique of choice is CT, in Europe the focus is more on MRI and ultrasound (US).
 Most patients with chronic IBD are diagnosed at a young age. After baseline diagnosis many of these
young patients have to undergo repetitive imaging procedures during the variable clinical course of the
disease, characterized by alternate periods of remission and active disease, and in monitoring the response
to treatment.

5. Intestinal ultrasound (IUS)
IUS is a widely available imaging modality associated with low costs, an excellent safety profile, and lack of
preparation. It is increasingly recognized as an accurate technique as part of the armamentarium for IBD
diagnosis, but also for assessing disease activity and extent, detecting complications, and monitoring response
to therapy

6. IUS Examination
Transabdominal high-frequency US does not provide
a continuous and complete examination of the small
and large bowel.
Following areas are easily assessed in most cases:
 Ileocecal region
 Sigmoid colon
 Left and right colon
Difficult regions
 Colonic flexures (especially the left flexure):
Difficult to visualize due to their cranial position
and ligamentous fixation to the diaphragm.
 Colon transversum: Complete examination is not
easy to achieve because of its variable anatomy
 Rectum and anal region cannot be visualized
accurately by the transabdominal route due to
their pelvic location.
 Transperineal US is useful in the evaluation of the
perianal region and the distal rectum.

7. Sonoanatomy of the normal intestinal wall
Layer echogenicity Anatomic structure
Hypoechoic (fluid) or hyperechoic (air) lumen
Hyperechoic entrance Transition lumen/mucosa
Hypoechoic Mucosa
Hyperechoic Submucosa
Hypoechoic Muscularis propria
Hyperechoic Transition muscularis
propria/serosa,
surrounding structures
(fat, peritoneal wall)
 With the use of high US frequencies in the range
from 7.5 MHz to 17 MHz, the wall of the intestine
usually exhibits five different layers
 With modern high-frequency linear array probes
the normal intestinal wall thickness is generally ≤
3 mm (using mild compression) ranging from
small diameters in the jejunum, ileum and
proximal colon to larger diameters in the sigmoid
colon (due to the hypertensive function of the
sigmoid zone).

8. Additional tools
Contrast-enhanced ultrasonography (CEUS)
 CEUS has been shown to more precisely
determine disease activity in CD patients
 CEUS has been shown to be capable of
determining bowel wall vascularity in patients
with CD and the findings correlate well with
those of magnetic resonance imaging (MRI)
European Federation of Societies for
Ultrasound in Medicine & Biology guidelines
Indications for the use of CEUS in IBD:
1. Estimation of disease activity
2. Distinguishing between fibrosis and
inflammatory strictures
3. Characterization of suspected abscesses
4. Confirming and following the route of a fistula

9. Crohn’s disease

10.  CD can be localized in any part of the
gastrointestinal tract, although the main location
is the terminal ileum.
Disease extent
 Small intestinal localization: 30-40%
 With involvement of the terminal ileum in 90%
 Ileum and colonic localization: 40-55%
 Colonic localization only: 15-25%

11. Signs of intestinal inflammation
Bowel features
 Increased bowel wall thickness (BWT):
 Small bowel: > 2–3 mm
 Large bowel: 3–4 mm
 Loss of bowel wall stratification (BWS)
 Increased vascularization
Extramural features
 Mesenteric fat proliferation
 Lymph nodes

12. Inflamed colon segment in Crohn’s disease
Characteristic appearance:
• Thickened wall diameter (almost 1 cm)
• Partial loss of wall stratification
• Prominent submucosal layer
• Narrowed lumen
• Mesenteric fat hypertrophy.

13. Complications
Intestinal strictures
 Strictures are usually defined by segmental
thickening of the bowel wall. Defining a stenosis
also requires the occurrence of prestenotic
dilatation.
 Differentiation between fibrotic and
inflammatory stenosis is a difficult issue in
patients with fibrostenotic CD.
IUS showing an ileal stenosis, with thickened bowel wall
with narrow lumen (asterisk) and prestenotic dilation
(arrow).

14. Complications
Fistula
 Hypoechoic tracts between bowel loops, or at
least with the origin in the bowel, and are
sometimes connected to other tissue or organs
such as the skin, the cystic bladder, or the vagina
IUS showing entero-enteric fistulae:
hypoechoic tracts connecting small bowel
loops (arrows).

15. Complications
Abscess
 Irregular, aperistaltic, hypoechoic zone without
vascularization and only a few internal echoes
CEUS showing differentiation between abscess and
inflammatory mass: Using CEUS this hypoechoic mass shows
three areas completely devoid of microbubble signal,
representing three abscesses.

16. Complications
Abscess
 Irregular, aperistaltic, hypoechoic zone without
vascularization and only a few internal echoes
CEUS showing differentiation between abscess and
inflammatory mass: Using CEUS this hypoechoic structure
shows intralesional enhancement and corresponds to an
inflammatory mass.

17. Ulcerative colitis

18. Ulcerative colitis
UC exclusively affects the colon with a predictable
way of spreading from distal to proximal colon in a
continuous manner.
Disease extent
 Proctitis
 Left-sided colitis
 Extensive colitis beyond the splenic flexure

19. IUS examination
The clinical role of US in UC is less well established as
compared with CD.
In contrast to CD, bowel thickening in UC could not
be correlated with clinical disease activity in some
studies
Characteristic features
 Mural stratification is preserved in most UC
patients due to the superficial pattern of
inflammation.
 Splanchnic flow measurements in the inferior
mesenteric artery have been shown to be closely
related to clinical and endoscopic disease activity
in patients with

20. IUS examination
Inflamed terminal ileum with increased bowel wall thickness (BWT) and intact stratification (left), normal BWT terminal
ileum (right)

21. Monitoring response to treatment
 Mucosal healing (MH) after short-term medical
treatment is being considered as an important
step in the therapeutic work-up of IBD patients
due to the potential prognostic role of MH in
predicting disease outcome.
 However, IBD patients are reluctant to be re-
endoscopes during follow-up; therefore, there is
a need for a non-invasive alternative index of MH
which can replace endoscopy in clinical practice.
Changes in ultrasound findings after anti-inflammatory treatment
(9 MHz probe) Joining pretherapeutic image (A) into actual finding
(B) at the same site after 2 weeks of treatment with anti-tumor
necrosis factor in acute Crohn’s disease: reduction of bowel wall
thickness and mucosal swelling (arrows)

22. Conclusion
In conclusion, IUS is an accurate non-invasive monitoring tool not only to assess IBD diagnosis, disease extent,
and activity in CD and UC, but also to monitor response to therapy. In experienced hands, IUS adds
extraordinary value to the management of IBD patients.

23. Additional reading
 Frias-Gomes, C., Torres, J., & Palmela, C. (2021). Intestinal Ultrasound in Inflammatory Bowel Disease: A
Valuable and Increasingly Important Tool. GE Portuguese journal of gastroenterology, 29(4), 223–239.
https://doi.org/10.1159/000520212
 Kucharzik, T., Kannengiesser, K., & Petersen, F. (2017). The use of ultrasound in inflammatory bowel
disease. Annals of gastroenterology, 30(2), 135–144. https://doi.org/10.20524/aog.2016.0105
 Maaser, C, Maconi, G, Kucharzik, T, Allocca, M. Ultrasonography in inflammatory bowel disease – So far we
are? United European Gastroenterol J. 2022; 10( 2): 225– 32. https://doi.org/10.1002/ueg2.12196

24. Thank You