Contributors: Barbara J Watrous
Species: Canine | Classification: Techniques
- Retrograde administration of positive, negative or a combination of contrast agents into the large intestine provides information about the intestinal lumen.
- Investigation of:
- Relatively simple procedure in most practices.
- Time consuming.
- May give limited information.
- Endoscopy Colonoscopy should precede barium study if doing procedure on same day.
- Ultrasonography (do not perform negative contrast study prior to ultrasonographic examination).
- 15 min.
- 20 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 suspect perforation of bowel water-based agent may be safer.
- X-ray machine.
- Processing facilities.
- Protective clothing (lead apron) for radiographer.
- Positioning aids (sandbags, cradle and ties).
- Method of labelling film.
- Foley or colon retention catheter.
- Enema pump or infusion tubing with large volume syringe.
- 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.
- Grid for examination of large dog.
- Radiographic film.
- Contrast agent.
- Water-soluble lubricant for catheter.
- Commercial barium enema kit.
- Withold food for 12-24 hours before procedure.
- General anaesthesia General anesthesia: overview usually required.
- Pneumocolon can be performed to identify the position of the colon without sedation.
- Large bowel must be completely emptied of faeces the night before the procedure.
- Administer cleansing enema Enema the night before and repeat at least 2-3 hours before study.
- Enema should be repeated until no residual material in colon.
Laxatives given the day before the procedure may help.
- Positive or negative or double contrast studies can be performed.
Double contrast study should be performed after positive contrast study.
- Positive contrast and double contrast studies allow evaluation of mucosal detail.
- Pneumocolon useful to identify position of colon and intraluminal masses, eg intussusceptions or strictures.
- Positive contrast:
- Liquid barium suspension can be diluted with warm water/saline to 20% w/v.
- Ideally disposable human enema bags (come complete with bag, barium, tube, catheter and clamp).
Step 1 - Control films
- Lateral abdominal radiograph Radiography: abdomen :
- Check exposure settings and processing.
Increase kV by 6-8 if performing positive contrast study.
- Confirm positioning adequate.
- Confirm diagnosis not apparent without contrast study.
- Check exposure settings and processing.
Step 2 - Prepare barium
- Prepare barium by adding water.
Step 3 - Insert catheter
- Insert lubricated catheter into rectum.
- May need purse string suture in anus, if balloon or colon retention catheter of sufficient size is not available.
Step 1 - Administer contrast
- Elevate bag (if using enema kit) and release clamp on infusion.
- Allow barium to flow into rectum under gravity.
- Dose 7-15 ml/kg.
- If commercial barium enema kit not available, insert Foley or retention balloon catheter into anus and inflate bulb.
- Inject contrast slowly using large syringe.
Alternatively use enema pump or fluid infusion and funnel may be used with contrast administered under gravity.
- Used most often as rapid method of determining colon location, not of mucosal or mural disease.
- Inject air 1-3 ml/kg to highlight colon.
- Inject positive contrast agent as above.
- Remove positive contrast agent before performing pneumocolon.
Step 2 - Obtain radiographic views
- Lateral, ventrodorsal and right and left lateral ventrodorsal oblique views should be taken.
Step 1 - Assess radiographs
- Normal colon has smooth mucosal surface on lateral and ventrodorsal views.
- After administering 10 ml/kg can take radiograph to check not over-distending bowel .
- Contrast entering small intestine may hinder interpretation.
- Add more contrast if necessary.
Step 2 - Remove catheter
- Remove catheter.
- Iatrogenic rupture of colon - avoid by using lubricated catheter and not over-inflating Foley catheter cuff.
Reasons for Treatment Failure
- Inadequate contrast administration.
Diseased colon is often more distensible than normal bowel so take radiograph to assess filling and then add more contrast if necessary.
- Recent references from PubMed and VetMedResource.
- Brawner W R & Bartels J E (1983) Contrast radiography of the digestive tract. Indications, techniques, and complications. Vet Clin North Am Small Anim Pract 13 (3), 599-626 PubMed.
- Nyland T G & Ackerman N (1978) Pneumocolon - a diagnostic aid in abdominal radiography. J A Vet Radiol Soc 19 (6), 203-209 VetMedResource.
Other sources of information
- Thrall D E (1998) The Textbook of Veterinary Diagnostic Radiology. 3rd edn. pp 560-570.
- American College of Veterinary Radiology, Executive Director, Dr M Berstein, P O Box 87, Glencoe, IL 60022, USA. www.acvr.ucdavis.edu