Contributors: Barbara J Watrous

 Species: Canine   |   Classification: Techniques

Introduction Requirements Preparation Procedure Aftercare Outcomes Further Reading

Introduction

  • Retrograde administration of positive, negative or a combination of contrast agents into the large intestine provides information about the intestinal lumen.

Uses

  • Investigation of:
    • Tenesmus, eg colitis Large intestine severe colitis - barium.
    • Large bowel diarrhea Diarrhea: chronic.
    • Hematechezia.
    • Suspected intussusception Intussusception.
    • Position of colon in relation to caudal abdomen/pelvic masses.
    • Suspected large intestinal obstruction, eg colonic mass Large intestine colonic tumor - barium.

Advantages

  • Relatively simple procedure in most practices.
  • Inexpensive.

Disadvantages

  • Messy.
  • Time consuming.
  • May give limited information.

Alternative Techniques

  • Endoscopy Colonoscopy should precede barium study if doing procedure on same day.
  • Ultrasonography (do not perform negative contrast study prior to ultrasonographic examination).

Time Required

Preparation

  • 15 min.

Procedure

  • 20 min.

Decision Taking

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?

Risk assessment

  • If suspect perforation of bowel water-based agent may be safer.

Requirements

Materials Required

Minimum equipment

  • X-ray machine.
  • Cassette.
  • 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.

Ideal equipment

  • 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.

Minimum consumables

  • Radiographic film.
  • Contrast agent.
  • Water-soluble lubricant for catheter.

Ideal consumables

  • Commercial barium enema kit.

Preparation

Dietary Preparation

  • Withold food for 12-24 hours before procedure.

Restraint

  • General anaesthesia General anesthesia: overview usually required.
  • Pneumocolon can be performed to identify the position of the colon without sedation.

Other Preparation

  • 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.
Choice of contrast study
  • 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).

Procedure

Approach

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.

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.

Core Procedure

 

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.
Using Foley catheter
  • 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.
Pneumocolon
  • 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.
Double contrast study
  • 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.

Exit

 

Step 1 - Assess radiographs

 
  • Normal colon has smooth mucosal surface on lateral Large intestine normal barium enema - barium VD and ventrodorsal Large intestine normal barium enema - barium VD views.
  • After administering 10 ml/kg can take radiograph to check not over-distending bowel Large intestine normal barium enema.
  • Contrast entering small intestine may hinder interpretation.
  • Add more contrast if necessary.

Step 2 - Remove catheter

 
  • Remove catheter.

Aftercare

Immediate

Potential complications

  • Iatrogenic rupture of colon - avoid by using lubricated catheter and not over-inflating Foley catheter cuff.

Outcomes

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.

Further Reading

Publications

Refereed papers

  • 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.

Organizations

  • American College of Veterinary Radiology, Executive Director, Dr M Berstein, P O Box 87, Glencoe, IL 60022, USA. www.acvr.ucdavis.edu