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FLUOROSCOPY
ColonDemonstration data

Contrast Enema

The contrast enema introduces contrast per rectum under fluoroscopic guidance to evaluate the colon. Applications range from diagnosis of distal obstruction, anastomotic leak and Hirschsprung disease to therapeutic reduction of paediatric ileocolic intussusception. Contrast choice is dictated by the indication: water-soluble agents for suspected leak, obstruction and pre-operative studies, and barium for detailed mucosal assessment when perforation is excluded.

Indications

  • Suspected distal large-bowel obstruction to identify the level and cause
  • Assessment of a colorectal anastomosis for leak or stricture before stoma reversal (water-soluble)
  • Therapeutic reduction of paediatric ileocolic intussusception under fluoroscopic or ultrasound guidance
  • Suspected Hirschsprung disease to demonstrate a transition zone and rectosigmoid index
  • Evaluation of colonic strictures, fistulae and post-surgical anatomy

Contraindications & Cautions

  • Suspected perforation, peritonitis or toxic megacolon: barium is contraindicated, use water-soluble contrast if any study is required
  • Peritoneal signs, shock or free intraperitoneal air contraindicate attempted intussusception reduction
  • Recent deep rectal biopsy increases perforation risk
  • Pneumatosis or suspected bowel necrosis
  • For anastomotic assessment use water-soluble contrast because a barium leak into the pelvis is harmful

Patient Preparation

  • Diagnostic mucosal studies require bowel cleansing; leak and obstruction studies are usually performed without full preparation
  • No preparation is given before intussusception reduction
  • Explain the procedure and obtain consent; for reduction ensure surgical and anaesthetic backup is available
  • Confirm the clinical question to select barium versus water-soluble contrast and single versus double contrast
  • Insert a rectal catheter; a balloon is used cautiously and avoided in neonates and after recent surgery

Technique & Parameters

  • Scout image then rectal instillation of contrast under fluoroscopic control
  • Single-contrast: dilute barium or water-soluble contrast to fill and profile the colon
  • Double-contrast: high-density barium coating followed by air insufflation for mucosal detail (perforation excluded)
  • Anastomotic leak study: water-soluble contrast instilled to the anastomosis with spot films in multiple projections
  • Intussusception reduction: controlled air (pneumatic) or water-soluble hydrostatic enema with the three-attempt rule and monitoring for reflux of contrast into the terminal ileum indicating success
  • Hirschsprung study performed without preparation using a soft catheter without a balloon, with a lateral rectal view to assess the rectosigmoid index

Systematic Review

  • Assess colonic calibre, haustration and any transition point
  • Evaluate mucosal contour for ulceration, polyps or masses
  • Identify strictures, fistulae and diverticula
  • For anastomoses inspect for contrast extravasation indicating a leak
  • For intussusception confirm reduction by free reflux of contrast into small bowel
  • For Hirschsprung assess the rectosigmoid ratio and the level of the transition zone

Key Findings & Significance

  • Apple-core annular narrowing with shouldered margins suggests colorectal carcinoma
  • Intussusception: meniscus or coiled-spring appearance with an obstructing soft-tissue mass
  • Successful reduction: contrast refluxes freely into the terminal ileum
  • Hirschsprung disease: reversed rectosigmoid index with a narrow aganglionic distal segment and dilated proximal colon
  • Anastomotic leak: extraluminal contrast tracking beyond the bowel wall
  • Diverticulosis with saccular outpouchings and possible fistula or stricture

Differential Considerations

  • Annular narrowing: carcinoma, diverticular stricture, ischaemia or Crohn stricture
  • Distal obstruction: neoplasm, volvulus, faecal impaction or hernia
  • Filling defect: polyp, carcinoma, faecal residue or air bubble
  • Microcolon in a neonate: distal ileal atresia, meconium ileus or total colonic Hirschsprung
  • Transition zone: Hirschsprung disease versus functional immaturity of the colon

Pearls & Pitfalls

  • Use water-soluble contrast for suspected leak, obstruction or perforation and for pre-reversal anastomotic studies
  • For intussusception the classic rule of threes guides safe reduction (three attempts, limited pressure and time); a palpable mass and reflux of contrast confirm outcome
  • Perform the Hirschsprung study without preparation and without a balloon to preserve the transition zone
  • Avoid rectal balloon inflation in neonates and recently operated bowel
  • Persistent obstruction after failed reduction requires prompt surgical referral

Structured Report

  • State the contrast agent, technique and indication
  • Describe colonic calibre, mucosa, strictures, masses and diverticula
  • For anastomoses explicitly state whether a leak is present or excluded
  • For intussusception document reduction success and any residual mass
  • For Hirschsprung give the rectosigmoid index and the transition zone level, and recommend biopsy

References

  • ACR-SPR Practice Parameter for the Performance of Contrast Enema Examinations in Adults
  • del-Pozo G et al. Intussusception in Children: Current Concepts in Diagnosis and Enema Reduction. RadioGraphics
  • ACR-SPR Practice Parameter for the Performance of Fluoroscopically Guided Reduction of Intussusception
  • 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.