Introduction Crohn's disease is an intestinal inflammatory disorder which frequently involves the small intestine. Accurate localisation of disease is important to direct targeted therapy. Video capsule endoscopy (VCE) has revolutionised clinical assessment of small intestinal Crohn's disease. Small bowel ultrasound (SB USS) is a rapid, inexpensive, interactive and non-invasive alternative method for assessing small bowel Crohn's disease, which is in routine use only at selected UK institutions. We evaluated the diagnostic yield of SB USS in VCE determined Crohn's disease.
Methods A retrospective assessment of patients who had undergone VCE in 2008–2010 was carried out. Patients investigated for suspected small bowel Crohn's disease, or who had findings of small bowel Crohn's on VCE were included, if they had also had a SB USS within 12 months. VCE findings were graded as mild (aphthous ulcers only), moderate (aphthous ulcers with mucosal distortion) or severe (aphthous ulcers with mucosal distortion and strictures/stenosis). SB USS was graded positive or negative for small bowel Crohn's disease. Both assessments were single operator. Either investigation could predate the other. Results were expressed as sensitivity, specificity, positive and negative predictive value (PPV and NPV) of SB USS compared with VCE for detection of small bowel Crohn's. Sub-analysis of SB USS findings for VCE-defined severity of small bowel Crohn's disease was carried out.
Results 196 VCE procedures were reviewed, of which 22 fulfilled the inclusion criteria. 10 patients had SB Crohn's on VCE; this was detected in four patients by SB USS (sensitivity 40%). 12 patients had no evidence of SB Crohn's on VCE; none of these had SB USS findings of Crohn's disease (specificity 100%). Of 18 patients with no evidence of SB Crohn's on SB USS, VCE findings of Crohn's disease were apparent in 6 patients (negative predictive value 67%); however, all patients with positive findings of Crohn's disease on SB USS had evidence of SB Crohn's on VCE (positive predictive value 100%). Sub-analysis for severity of inflammation on VCE was carried out. Of four patients with positive findings at SB USS, 3 were severe and one moderate on VCE. One patient with severe Crohn's on VCE was missed by SB USS; however, the patient's body habitus was unfavourable.
Conclusion SB USS has excellent positive predictive value (100%) and specificity (100%) for detection of SB Crohn's disease, with only moderate negative predictive value (67%). In addition, all detected cases were moderate or severe, which may complicate VCE. It therefore seems a safe, quick, relatively cheap initial investigation in expert hands, which may obviate more costly, invasive investigations. A prospective evaluation of these diagnostic modalities should be carried out.
Competing interests None declared.
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