Radiography: abdomen

• A large amount of information can be obtained from a plain abdominal radiograph if it is produced to a high standard and interpretation skills are high.
• Plain abdominal radiography may need to be supplemented by contrast studies where further information is required about the urinary or gastrointestinal tracts.
• Ultrasonography is often a valuable supplementary procedure.
• As the inherent subject contrast is low, particularly in thinner patients (with little abdominal fat), image contrast must be maximized by:
  • Using relatively low kV values.
  • Selecting films with higher inherent contrast.
• Breathing blur may occasionally be a problem, particularly when using lower output x-ray machines, but as the film is ideally exposed on expiration, blur is less likely than in thoracic radiography.

Exposure on expiration facilitates better demonstration of abdominal contents, in addition to minimizing risk of breathing movement blur.

• Close collimation of the primary beam should be practiced at all times.
• The objective is to produce a radiograph which includes the whole area of interest, is correctly exposed and developed, and is free from movement blur and artifacts.
• The film should be clearly marked with an anatomical marker, the patient's identification, the date and the name of the hospital or practice.

Print off the Owner factsheetXrays and ultrasound - why they help my vet  Xray and Ultrasound  to give to your clients.

Uses

• Assessing size, shape and position of abdominal organs         .
• Detection of:
  • Abdominal mass(es), eg abscess or neoplasia         .
  • Gastrointestinal stasis, obstruction (gas patterns     ) or impaction         .
  • Peritonitis or free abdominal fluid.
  • Genital tract abnormalities or pregnancy     .
  • Urinary tract abnormalities, including urolithiasis (with radio-opaque urinary calculi     ) or bladder rupture.
  • Arteriosclerosis   Arteriosclerosis  .
• Investigation of incontinence.

Advantages

• Non-invasive.
• Relatively simple procedure.

Disadvantages

• Larger amounts of gas and ingesta in the abdomen of rabbits compared to cats and dogs makes interpretation difficult.
• Supplementary procedures such as ultrasonography or contrast studies are frequently required.

Rabbits normally have ingesta within their stomachs at all times - this hinders evaluation of contrast studies of the gastrointestinal tract. Contrast is often not helpful in diagnosis of phyto- and trichobezoars.

• Shortcomings in technique make interpretation particularly difficult, eg a low contrast image may mimic pathology.

Technical problems

• Restraint may involve sedation or general anesthesia.

Alternative techniques

• Ultrasonography may be an alternative but this has its own inherent problems and is more often used in conjunction with radiography.

Time required

Preparation

• Dependent upon the method of chemical restraint (sedation or anesthesia).

Procedure

• For plain abdominal radiography: 10-15 min or longer, dependent upon skill of radiographer.

Decision taking

Criteria for choosing test

• Can you make the diagnosis without it?
• Can it tell you what you need to know?
• Will your management be affected by the radiological findings?

Choosing the right projections

• Lateral recumbency:
  • Right lateral recumbency = first standard projection.
  • Gives information on size, shape and position of most abdominal organs     .
  • The second lateral recumbency projection is of limited use in plain radiography of the abdomen. In some cases it may allow a gas bubble, eg in the stomach, to rise and fill the opposite side of the structure, thus optimizing visibility of that structure's lumen, or clarifying its position.
• Ventrodorsal:
  • Ventrodorsal = second standard projection.
  • Gives additional information on size, shape and position of abdominal organs     .

Particularly useful for separately viewing the kidneys.

Do not attempt ventrodorsal projection (necessitating dorsal recumbency) if pleural fluid or other severe respiratory dysfunction is suspected.

• Dorsovental:
  • Dorsoventral = useful when ventrodorsal positioning is not possible, or to cause gas to rise to a different position within a structure.

Risk assessment

• Take a complete history and perform a full clinical examination of the patient before embarking on any stressful procedure, particularly when chemical restraint is necessary.