Indications

Crohn's disease evaluation (initial diagnosis, disease extent, complications)
Small bowel obstruction localization
Malabsorption workup
Meckel's diverticulum evaluation (adjunct to nuclear medicine)
Post-surgical small bowel evaluation
Obscure GI bleeding when other studies negative

Normal Anatomy and Landmarks

Segment	Normal Appearance
Jejunum	Left upper and mid abdomen; prominent valvulae conniventes (Kerckring folds); feathery/herringbone mucosal pattern; 2.5–3 cm caliber
Ileum	Right lower abdomen; fewer and less prominent folds; smoother mucosa; 2–2.5 cm caliber
Terminal ileum (TI)	Right iliac fossa; nodular lymphoid tissue (lymphoid hyperplasia) is normal in children; ileocecal valve — lips project into cecum
Ileocecal valve	Smooth, symmetric filling defect at cecum; barium refluxes through in ~50% of normal studies
Transit time	Gastric emptying to cecal filling: 2–6 hours

Jejunal vs. ileal folds. Jejunum has more and taller valvulae conniventes (3–5/inch) than ileum — important for assessing fold pattern abnormalities. Loss of folds (diluted barium, sprue) or thickened folds (edema, Crohn's, amyloid) are regional findings.

Key Findings

Crohn's Disease

Finding	Description
Aphthous ulcers	Earliest finding — tiny barium collections with surrounding edematous halo; easily missed
String sign of Kantor	Marked narrowing of a long segment of terminal ileum from wall edema and/or spasm; may represent severe active disease
Cobblestone mucosa	Deep ulceration + submucosal edema separates islands of intact mucosa — "cobblestone" appearance; indicates transmural disease
Rose-thorn ulcers	Deep, spiked longitudinal ulcers along the mesenteric border; characteristic of transmural ulceration
Skip lesions	Involved segments separated by normal bowel — pathognomonic for Crohn's (vs. UC which is continuous)
Strictures	Smooth narrowing from fibrotic stenosis; ± prestenotic dilation; single or multiple
Fistulas	External fistula (enterocutaneous), internal (enteroenteric, enterovesical); barium opacifies fistulous tract
Separation of bowel loops	Mesenteric thickening, phlegmon, or abscess; compare with CT for mesenteric inflammation

String sign caution. A tight string sign may represent severe active inflammation (responsive to medical therapy) OR fibrotic stricture (requiring surgery). Fluoroscopy cannot reliably distinguish — CT or MR enterography with bowel wall enhancement is required to differentiate.

Other Small Bowel Findings

Finding	Features
Celiac disease (sprue)	Jejunal fold effacement (jejunization of ileum); moulage sign (smooth, featureless barium column); fold reversal (ileum folds > jejunum); dilution of barium
Intussusception	Coiled spring appearance of invaginated bowel; filling defect; most small bowel intussusceptions are transient and self-limiting in adults (unlike ileocolic)
Small bowel obstruction	Dilated loops (>3 cm); air-fluid levels (on upright); transition point to decompressed bowel; string-of-beads sign (gas trapped between valvulae)
Meckel's diverticulum	Blind-ending diverticulum from antimesenteric border of distal ileum ~60 cm from ileocecal valve; often not seen on SBFT — nuclear medicine (Meckel's scan) is preferred

Reporting Checklist

Mucosal fold pattern: normal / thickened / effaced / cobblestoned / skip lesions
Luminal caliber: normal / dilated / strictured — location and length of any stricture
Terminal ileum: normal / narrowed / ulcerated / lymphoid hyperplasia
Ileocecal valve: normal / enlarged / abnormal
Fistulas: present / absent — if present, course and endpoint
Transition point (if obstruction): location, degree (complete vs. partial)
Transit time: normal / rapid (hypermotility) / delayed (obstruction, hypomotility)
Crohn's: extent and distribution; skip lesions; complications (abscess, fistula, obstruction)

Common Pitfalls

Pitfall	How to Avoid
Missing aphthous ulcers	Earliest Crohn's lesions are very subtle — dedicated spot compression views of TI are essential; use paddle compression
Underdistension of loops	Overlapping loops prevent assessment; prone positioning and compression separate loops; obtain multiple timed overhead films
String sign misinterpreted as normal narrowing	TI can appear narrow from spasm — compression and prone views may relax the segment; persistent narrowing on multiple views = true stricture
Meckel's diverticulum missed	SBFT has low sensitivity for Meckel's — if suspected clinically, Tc-99m pertechnetate scan is the preferred study
Cecal filling confused with mass	Ileocecal valve fill-in, lymphoid hyperplasia, and cecal impression on TI — verify with compression views and multiple positions

Step-by-step fluoroscopy technique and systematic search patterns available in RadCall Pro.

Small Bowel Follow-Through — Interpretation and Findings