What is a Small Bowel Series?
A small bowel series is a fluoroscopic barium examination of the small intestine, typically performed using either a small bowel follow-through (SBFT) technique where barium is ingested orally, or a small bowel enteroclysis (SBE) where barium is infused through a nasojejunal tube to achieve optimal bowel distention. 1
Technical Methods
Small Bowel Follow-Through (SBFT)
- The patient ingests barium contrast orally, and serial radiographs are obtained as the contrast progresses through the small bowel 1
- SBFT is less invasive and better tolerated by patients compared to enteroclysis, as it does not require nasojejunal intubation 1
- The examination is limited by nonuniform small bowel filling and cannot adequately test bowel distensibility 1
- Intermittent fluoroscopy is used to track contrast progression, which may miss subtle abnormalities 1
Small Bowel Enteroclysis (SBE)
- Requires placement of a nasojejunal tube with active controlled infusion of barium contrast to optimize bowel distention 1
- SBE is inherently more invasive with tube placement resulting in higher radiation exposure compared to SBFT 1
- The technique provides superior bowel distention, clearly demonstrating morphological changes 2
- Patient acceptance is lower due to the discomfort of nasojejunal intubation 1
Clinical Applications
Historical Role
- Barium examinations were long established as the standard means of assessing small bowel mucosa 1
- SBFT and SBE served as benchmarks for comparison with other imaging modalities 1
Current Diagnostic Utility
- The diagnostic accuracy for detecting small bowel lesions ranges from 65% for routine SBFT to 96% for SBE 3
- SBFT has demonstrated usefulness in managing suspected small bowel obstruction in 68-100% of cases 1
- For celiac disease diagnosis, SBE allowed definite diagnosis in 34 of 42 patients (pattern 1: reversal of jejuno-ileal fold pattern) 4
- The specificity for excluding small bowel disease is approximately 92% when performed optimally 1
Limitations and Declining Use
Diagnostic Limitations
- SBFT has limited sensitivity (48-50%) and specificity (94%) for detecting low-grade or intermittent obstruction 1
- Plain fluoroscopy cannot directly visualize bowel wall thickness or extraluminal pathology such as abscesses 1
- The technique has limited value in routine assessment due to failure to adequately assess disease distribution or activity 1
- For inflammatory bowel disease in children, SBFT showed only 42% sensitivity compared to Tc-HMPAO scanning 1
Modern Alternatives
- Cross-sectional modalities such as CT and MRI enterography have emerged as preferred imaging tests for small bowel evaluation 1
- MR enterography has higher sensitivity (83%) and specificity (95%) compared to SBFT (76% and 67% respectively) 1
- There has been a significant decrease in SBFT use with widespread adoption of cross-sectional imaging—one study showed average use dropped from 0.05 per Crohn's patient per year in 2001 to 0.01 in 2010 1
Radiation Considerations
- Barium studies involve considerable radiation exposure, though lower than CT 5
- Excessive fluoroscopy time and number of radiographs can result in radiation doses equivalent to CT 1
- This is particularly concerning for children and patients requiring repeated examinations 1
Current Clinical Niche
When to Consider Small Bowel Series
- SBFT may serve as a problem-solving examination following equivocal CT, particularly for low-grade or intermittent partial obstruction 1
- The examination remains an option for stricture assessment during contrast injection 1
- SBFT may serve as an alternative to MRI and CT to avoid sedation, particularly in younger children 1
- Cutaneous fistula evaluation may benefit from fluoroscopic assessment 1