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FLUOROSCOPY
Small BowelDemonstration data

Small-Bowel Follow-Through

The small-bowel follow-through images the jejunum and ileum after oral ingestion of contrast, with serial films and fluoroscopic compression spot views tracking the bolus to the caecum. It evaluates mucosal disease, strictures, fistulae and transit, and remains useful where cross-sectional enterography is unavailable, though CT and MR enterography are now often preferred for Crohn disease.

Indications

  • Suspected or known Crohn disease to assess distribution, strictures and fistulae
  • Suspected low-grade or intermittent small-bowel obstruction
  • Malabsorption and chronic diarrhoea of unclear cause
  • Suspected small-bowel tumour, polyposis syndrome or bleeding source
  • Evaluation of post-surgical anatomy, blind loops and enteric fistulae

Contraindications & Cautions

  • Suspected perforation or free leak: use water-soluble contrast rather than barium
  • Suspected high-grade or complete mechanical obstruction: barium proximal to an obstruction may inspissate, so use water-soluble contrast
  • High aspiration risk: use a low-osmolar non-ionic agent
  • Toxic megacolon or acute severe colitis

Patient Preparation

  • Nil by mouth for at least 6 hours before the examination
  • Low-residue diet the preceding day may improve mucosal coating in some protocols
  • Explain that the study may take one to several hours as contrast transits the bowel
  • Confirm no suspected perforation before choosing barium
  • Metoclopramide may be given to accelerate gastric emptying and transit if not contraindicated

Technique & Parameters

  • Patient drinks a measured volume of dilute barium (or water-soluble contrast) and additional aliquots to maintain a continuous column
  • Overhead abdominal films taken at intervals (for example every 15-30 minutes) to follow the bolus
  • Intermittent fluoroscopy with graded compression to separate and profile individual loops
  • Dedicated compression spot views of the terminal ileum with the patient prone or in oblique positions
  • Study continues until contrast reaches the caecum and the terminal ileum is adequately demonstrated
  • Peroral pneumocolon or enteroclysis technique used where higher sensitivity is required

Systematic Review

  • Assess overall transit time and bowel calibre for dilatation or obstruction
  • Evaluate the fold pattern for thickening, effacement or a featureless ileum
  • Inspect the terminal ileum for ulceration, narrowing and nodularity
  • Look for separation of loops indicating bowel wall thickening or mesenteric disease
  • Identify strictures, skip lesions, fistulae and sinus tracks
  • Assess for filling defects suggesting polyps, tumours or intraluminal contents

Key Findings & Significance

  • Crohn disease: aphthous and deep ulcers, cobblestoning, skip lesions and terminal ileal strictures (string sign)
  • Separation and displacement of loops from mesenteric inflammation or mass
  • Fistulae and sinus tracks connecting bowel loops or to skin, bladder or vagina
  • Mechanical obstruction: dilated proximal loops with a transition point and collapsed distal bowel
  • Malabsorption: dilated loops, flocculation and dilution of contrast
  • Small-bowel tumour: annular narrowing, intraluminal mass or intussusception

Differential Considerations

  • Terminal ileal disease: Crohn disease, tuberculosis, backwash ileitis, infection (Yersinia) or lymphoma
  • Multiple strictures: Crohn disease, radiation enteritis, ischaemia or NSAID enteropathy
  • Fold thickening: infiltration, oedema, haemorrhage, Whipple disease or infection
  • Filling defects: polyps, metastases, carcinoid, lymphoma or retained food
  • Dilated bowel: obstruction, ileus, scleroderma or coeliac disease

Pearls & Pitfalls

  • Dedicated compression views of the terminal ileum are the highest-yield part of the study
  • A featureless dilated jejunum with jejunisation of the ileum suggests coeliac disease
  • Use water-soluble contrast when obstruction or perforation is suspected
  • CT and MR enterography better assess extraluminal disease and are often preferred for Crohn disease
  • Persistent narrowing that does not distend indicates a fixed stricture rather than spasm

Structured Report

  • State the contrast agent, transit time and completeness to the caecum
  • Describe calibre, fold pattern and mucosal abnormalities by segment
  • Characterise strictures, skip lesions, fistulae and any transition point
  • Give particular attention to the terminal ileum
  • Provide an impression and recommend cross-sectional enterography where appropriate

References

  • ACR-SPR Practice Parameter for the Performance of the Barium Small Bowel Examination
  • Maglinte DDT et al. Small-Bowel Radiography: How, When, and Why. Radiology
  • Nolan DJ, Traill ZC. The Current Role of the Barium Examination of the Small Intestine. Clinical Radiology
  • Royal College of Radiologists iRefer: Making the Best Use of Clinical Radiology

Educational clinical decision support only. Protocols vary by institution and equipment; always confirm with a qualified radiologist and local guidelines before clinical use.