When patients are experiencing pain, physicians may take a number of steps to assess the pain and attempt to determine its cause. Evaluation typically begins with a medical history and physical examination.

Physicians may ask the patient to describe the pain, including its location, severity and duration. Physicians may use a pain diagram (a picture of the human body) to evaluate pain. Patients mark the area(s) where pain is being experienced. Physicians may also use pain scales, which help quantify the pain, or other types of pain assessment.

To identify the cause of pain, physicians may conduct a number of tests. Some tests are definitive for a disease, but in many cases a test can only narrow the list of possible causes, rule out certain conditions, show a nonspecific problem such as inflammation or indicate the need for additional testing. Categories of tests include:

• Lab tests. Assessments that involve analysis in a laboratory include:
  
  
• • Blood tests. Samples of blood can reveal abnormal amounts of hormones, enzymes or other substances. Types of blood tests include complete blood count, C-reactive protein test, enzyme test, rheumatoid factor test, sedimentation rate and waste product test.
    
    
  • Urine tests. These reveal substances that can indicate diseases ranging from gout to prostatitis.
    
    
  • Spinal tap (lumbar puncture). Spinal fluid is extracted from the lower back and tested to determine pressure and contents. It is performed to diagnose conditions including meningitis and encephalitis.
    
    
  • Biopsy. A sample of tissue is taken and analyzed. Biopsies reveal cancer and can be used in revealing organ damage caused by disorders including lupus.
    
    
• Imaging tests. Examples of tests that depict internal structures include:
  
  
• • X-ray. Produces an image of a body part, organ or bodily system on film or fluorescent screens.
    
    
  • MRI (magnetic resonance imaging). Uses powerful magnets to produce images on a computer screen and film.

• • CAT scan (computed axial tomography). Allows for multiple x-rays to be taken from different angles around the patient.
    
    
  • Ultrasound. Uses high-frequency sound waves to create images on a computer monitor.
    
    
  • Bone scan and other types of radionuclide imaging. Introduce radioactive tracers into the body that emit rays detected by special devices.
    
    
  • Arthography. Injects a contrast medium into a joint to enhance an x-ray.
    
    
  • Discography. Injects a contrast agent into an intervertebral disc, followed by an x-ray.
    
    
• Electrodiagnostic testing. Tests that measure the electrical activity of nerves and muscles include:
  
  
• • Nerve conduction studies (NCS). Tests that evaluate for muscle or nerve damage.
    
    
  • Electromyography (EMG). Tests that identify muscles and nerves affected by weakness or pain.
    
    
• Quantitative sensory testing. These tests assess damage or changes to nerve endings.