- Ultrasound scan
- Magnetic resonance imaging (MRI) scan
- Computerized tomography (CT) scan
Your doctor will first take a detailed history and a physical examination to look for an external opening on the skin. Pus drainage can be often seen from the external opening. If an external opening is visible, your doctor will then try to determine the depth and direction of the fistula tract.
Your doctor may also perform a digital rectal examination (DRE). It is a simple bedside procedure in which your doctor will insert a gloved finger into your anus to look for any abnormality. Proctoscopy or anoscopy is also usually performed.
You doctor may also advise further testing to look for the openings of anal fistula. These tests may include: