*  cholangiography
    *  cholangiopancreatography, endoscopic retrograde
    *  cholangiopancreatography, magnetic resonance
    *  cholecystography
    *  colonography, computed tomographic
    *  endoscopy, digestive system
    *  cholangiopancreatography, endoscopic retrograde
    *  endoscopy, gastrointestinal
    *  colonoscopy
    *  sigmoidoscopy
    *  duodenoscopy
    *  gastroscopy
    *  proctoscopy
    *  esophagoscopy
    *  esophageal ph monitoring
    *  gastric acidity determination
    *  gastrointestinal transit
    *  lactose tolerance test
    *  liver function tests
    *  pancreatic function tests
    *  portography
    *  sialography