All medical work ups begin with a complete physical examination. Sometimes a diagnosis can be made based on physical examination findings alone; other times more tests are required. A minimum database for most illnesses includes a complete blood count (CBC), serum chemistry, and urinalysis. In addition, radiographs (x-rays) and/or more specific, specialized tests may be needed. Hospitalization, intravenous fluid administration, and injectable medications are often necessary for severe illnesses. Complex cases may require referral for additional imaging (ultrasound, CT scan, MRI) and diagnostic tests.