Contributors: Barbara J Watrous
Species: Feline | Classification: Techniques
- Use of positive contrast to outline the esophagus.
- Investigation of:
- Simple and quick to do.
- May not identify functional disorder.
- Some risk associated with procedure, eg contrast aspiration.
- Esophagoscopy Esophagoscopy.
- Fluoroscopy (gives more information about esophageal function).
- Ultrasonography for mediastinal/cervical masses.
- 5 min.
- 15 min.
Criteria for choosing test
- Is the examination appropriate?
- Can you make the diagnosis without it?
- Will your management of the case be affected by the outcome of the examination?
- If esophageal perforation suspected barium is contraindicated.
Water-soluble contrast is usually hyperosmolar and if it enters thoracic cavity or lungs can result in pleural or pulmonary effusion so may be more hazardous than a small amount of barium leakage.
- Risk of barium aspiration if pharyngeal dysfunction or regurgitation.
If can make diagnosis on plain radiograph do not do esophagogram.
- X-ray machine.
- Processing facilities.
- Protective clothing (lead apron) for radiographer.
- Positioning aids (sandbags, cradle and ties).
- Method of labeling film.
- Ability to process films during procedure so that repeat radiographs can be taken during course of study if required.
- High output x-ray machine.
- High definition screen.
- Radiographic film.
- Contrast agent.
- No special requirements for fasting patient.
- Ideally performed in unsedated patient as general anesthesia and sedation can produce transient megaesophagus, or mimic strictures due to bolus retention.
- If necessary use low dose acepromazine Acepromazine maleate 0.05-0.1 mg/kg.
Step 1 - Control films
- Lateral thoracic Radiography: thorax and cervical radiographs:
- Check exposure settings and processing.
- Confirm positioning adequate.
- Confirm diagnosis not apparent without contrast study.
Step 2 - Selection of contrast agent
- Water-soluble iodine-based contrast agent if esophageal perforation a possibility.
Still some risk as hypertonic iodine-based contrast agents may → pulmonary edema if aspirated.
- Barium or barium/food mixes are best for demonstrating esophageal strictures or diverticulae.
- Barium paste best for mucosal lesions.
- Barium liquid may pass around a partial obstruction and produce false normal radiograph; but may be useful in highlighting foreign body.
Step 1 - Administer contrast agent
- If assessing mucosal detail apply 5-10 ml barium paste to back of tongue.
- May take several minutes to coat esophagus.
- If suspect esophageal diverticulum or stricture administer contrast by syringe into buccal pouch taking care to avoid aspiration, by using minimal sedation and keeping head and neck flexed.
- Dose 5-15 ml (liquid barium 70-100% w/v).
- Alternatively mix barium with palatable food and persuade animal to eat.
Administration of IV diazepam Diazepam may stimulate eating immediately post-injection.
Step 2 - Obtain radiographic views
- Take lateral and DV/VD cervical and thoracic Radiography: thorax projections, encompassing cranial and caudal and esophegeal sphincters.
Step 1 - Assess radiographs
- For technical quality and to ensure lesion (if present) adequately shown.
- The esophagram may be exposed just as a bolus of contrast material is moving through the esophagus.
If there is any doubt as to the presence of stenosis or dilation a repeat radiograph should be taken.
- The caudal third of the feline esophagus is smooth muscle and has a classical 'herring bone' appearance with esophagography.
Do not misinterpret this as pathology.
Step 2 - Additional radiographic projections
- If suspect partial obstruction on films produced using liquid barium it may be necessary to repeat study with barium and meat.
- Aspiration of iodine-based contrast resulting in pulmonary edema.
- Leakage of iodine-based contrast from esophageal perforation may result in pleural effusion.
- Aspiration of barium may → aspiration pneumonia but usually only coats trachea and removed by action of cilia and coughing.
- Even with aspiration of a large amount of barium sulfate, cough reflux will clear that in the airways. Alveolarized barium sulfate will be phagocytozed by macrophages. The inert character of the contrast medium provides good long-term prognosis.
Reasons for Treatment Failure
- Motility disorder may not be diagnosed.
- Barium liquid bypasses partial obstruction.
- Unable to get animal to eat barium and food mix.
- Recent references from PubMed and VetMedResource.
- Tamm I & Kortsik C (1999) Severe barium sulfate aspiration into the lung - Clinical presentation, prognosis and therapy. Respiration 66 (1), 81-84 PubMed.
Other sources of information
- Thrall D E (1998) Textbook of Veterinary Diagnostic Radiology. pp 269-284.
- Klein L J (1974) Radiologic examination of the esophagus in dogs and cats. Vet Clin North Am 4, 663-686.