What is the preparation protocol for a Computed Tomography (CT) Enterography procedure?

CT Enterography Preparation Protocol

Patients should ingest 900-1,500 mL of neutral oral contrast in divided doses over 45-60 minutes before the examination, following a 4-6 hour fast from solids. 1, 2

Fasting Requirements

• Solid foods must be restricted for 4-6 hours prior to CT enterography 1, 2
• Liquids should also be restricted during this period, though water is permissible 1, 2
• This fasting period ensures adequate gastric emptying and optimal small bowel visualization 1

Oral Contrast Administration

Volume and Timing

• The standard volume is 900-1,500 mL of oral contrast, with volumes exceeding 1,000 mL providing superior bowel distension 2
• Diagnostically acceptable images can be obtained with as little as 450 mL, though this is suboptimal 1, 2
• Oral contrast should be ingested 45 minutes before image acquisition 1
• The contrast is typically divided into multiple doses over the 45-60 minute ingestion period 1, 2

Contrast Agent Selection

• Neutral oral contrast agents (with attenuation values near water) are preferred for CT enterography 1
• Acceptable agents include mannitol, polyethylene glycol (PEG), sorbitol, or combinations thereof 1
• No evidence favors one hyperosmolar preparation over another 1
• Negative oral contrast agents should NOT be used, as they obscure active bleeding and hyperenhancing lesions 1

Important Patient Counseling

Patients should be warned that they may experience cramping and diarrhea after ingesting hyperosmolar oral contrast agents 1

Critical Pitfalls to Avoid

• Studies performed without adequate oral contrast preparation have inferior diagnostic accuracy compared to properly prepared studies 1, 2
• Insufficient bowel distension is a major cause of suboptimal examinations 1, 2
• Avoid oral phosphate-containing preparations in patients with GFR <60 mL/min/1.73 m² due to risk of phosphate nephropathy 2
• Do not administer positive oral contrast (barium or iodinated agents at high concentrations), as these obscure mucosal enhancement patterns critical for detecting inflammation and vascular lesions 1

Additional Preparation Considerations

• Patients should be well hydrated prior to and following intravenous contrast administration 3
• No bowel purgative or cathartic preparation is routinely required for CT enterography, unlike CT colonography 1
• Additional colonic preparation is not required for routine CT enterography unless specific colonic evaluation is needed 1

Technical Execution

• Imaging should be performed during the enteric phase (50-70 seconds after starting intravenous contrast injection) 1
• Multiphase acquisitions may be performed for suspected vascular lesions, adding arterial and delayed phases 1
• Slice thickness should be 2-3 mm for optimal visualization 1