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.

Small-Bowel Follow-Through

📋 Indications

⛔ Contraindications & Cautions

🧑‍⚕️ Patient Preparation

⚙️ Technique & Parameters

🔎 Systematic Review

🩻 Key Findings & Significance

🧠 Differential Considerations

💡 Pearls & Pitfalls

📝 Structured Report

📚 References