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.

Contrast Enema

📋 Indications

⛔ Contraindications & Cautions

🧑‍⚕️ Patient Preparation

⚙️ Technique & Parameters

🔎 Systematic Review

🩻 Key Findings & Significance

🧠 Differential Considerations

💡 Pearls & Pitfalls

📝 Structured Report

📚 References