When to use abdominal imaging in primary care

• Determine if imaging is needed for your patient based on patient history, the results of physical examination, selected pathology tests if appropriate and considering the probability of disease.
  
• To ensure an imaging referral is justified, consider whether the results will assist in diagnosis and patient management.
  
• Having a provisional diagnosis and clear clinical question in mind can help focus the investigation, and noting these in the referral can assist the radiologist's interpretation of results.
  
• Clinical guidelines are available from the Diagnostic Imaging Pathways, and can help you to select the most appropriate diagnostic imaging test for your patient.
  

For a patient presenting with chronic abdominal pain, basic investigations including patient history, physical examination and simple blood tests may reveal findings of concern, abnormal results or red flag symptoms.¹ 

Imaging may be appropriate when:

• the probability of disease in the patient has been considered²
  
• the imaging test will assist in diagnosis and/or inform patient management³
  
• a clear, specific question is being asked of the test – to focus the interpretation of results.⁴

The most common causes of chronic abdominal pain include irritable bowel syndrome (IBS), Mittelschmerz/dysmenorrhoea and peptic ulcer (see below).⁵

The probability of particular conditions in your patient can often be established through patient/family history and physical examination,⁶ particularly in the presence of red flags or alarm symptoms.⁷

Considering the probability of particular conditions can help to inform whether further tests, such as blood tests and/or imaging, are necessary and, if they are, which tests are likely to be of most benefit.^2,6

Common causes of chronic or recurrent abdominal pain⁵

Most common causes (in adults)

• Irritable bowel syndrome (IBS)
  
• Mittelschmerz/dysmenorrhoea
  
• Peptic ulcer/gastritis
  

Causes often missed

• Adhesions
  
• Appendicitis
  
• Chronic pancreatitis
  
• Constipation
  
• Crohn disease
  
• Diverticulitis
  
• Endometriosis
  
• Food allergies
  
• Lactase deficiency
  

Adapted from Murtagh's General Practice (7th Edition)⁵

CT (computed tomography) scans for abdominal pain in non-urgent cases rarely result in diagnosis when warning signs such as unintentional weight loss, anaemia, vomiting, abdominal mass or fever are absent.⁸ Therefore, when the available clinical information can be used to confidently 'rule in' or 'rule out' a diagnosis, it is worth considering if an imaging test is necessary.²

Consider the following questions before referring your patient with abdominal pain for an imaging test:³

• Will it affect diagnosis?
  
• Will it change management?
  
• Are there previous imaging results that provide diagnostic or management information?
  
• What is the most appropriate imaging technology? Can the same information be obtained without exposure to ionising radiation?
  
• Will it do more harm than good?
  

When imaging is needed, choose the right modality for your patient

To help select the most appropriate imaging test, consult the Diagnostic Imaging Pathways (DIP) from the WA Department of Health.

These pathways were developed in consultation with GPs, specialist clinicians and radiologists.⁹

The following recommendations extracted from DIP guidelines may be useful to keep in mind for patients with chronic abdominal pain:⁷

1. Use ultrasound as a primary investigational tool in children, adolescents, women who are pregnant or of child-bearing age, and for patients with suspected biliary disease and upper right-quadrant pain.
2. Imaging is usually not needed for patients with suspected IBS, unless alarm symptoms are present with upper right-quadrant pain and biliary symptoms (ultrasound).
   

   Alarm symptoms include:
   - anaemia
   - antibiotic use
   - awakened by gastro-intestinal symptoms
   - blood in stools
   - family history of colon cancer
   - symptom onset after age 50
   - unexplained weight loss.⁷

3. Imaging for dyspepsia is not needed unless warning features are present in combination with a normal endoscopy result. Selection of imaging modality depends on whether the cause is suspected to be biliary (ultrasound) or pancreatic (CT).
   
   Warning features for dyspepsia include:
   - age > 55 years and recent onset of symptoms
   - anaemia
   - bleeding
   - daily constant pain
   - dysphagia
   - epigastric mass
   - history of gastric ulcer or gastric surgery
   - NSAID use
   - vomiting
   - weight loss.⁷

4. Limit use of diagnostic imaging for non-specific chronic abdominal pain to patients with red flags or situations such as:
   - pain through to the back (CT)
   - pelvic pain (ultrasound or CT, depending on suspected diagnosis)
   - renal colic, if younger than 50 years old at first presentation (ultrasound or CT, depending on clinical situation), or if pregnant (ultrasound)
   - suspected Crohn's disease
   - first-line diagnostic imaging is ultrasound, followed by colonoscopy and biopsy
   - CT or MRI (magnetic resonance imaging) may be required to assess extent and extramural disease, or when the patient fails to respond to treatment
   - suspected pancreatic disease (CT)

   Note: this is a general summary of the guidance for investigating chronic abdominal pain. To see the complete guidance for chronic abdominal pain, visit the Diagnostic Imaging Pathways pages on abdominal pain (chronic).
   

The reason for the investigation and a clear clinical question to be answered by the investigation can help determine which imaging test is most appropriate, and will assist in the radiologist's interpretation of the results.^3,4

Remember to note these details and the provisional diagnosis in the imaging referral.^3,4

Find out more about the essential inclusions in an imaging referral.