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Test Code NBLD0219 Diagnostic Occult Blood, Gastric (Guaiac)

Useful For

  • The early detection of gastric trauma or deteriorating gastric condition
  • Evaluating antacid therapy
  • Evaluating the placement of a gastric tube


Occult Blood: Gastroccult buffered guaiac peroxidase

pH: Dye color change

Performing Laboratory

Bozeman Health Laboratory Services

Specimen Requirements

Specimen Type: Gastric aspirate or vomitus

Container/Tube: Sterile leakproof container

Specimen Volume: 1 mL

Collection Instructions:  

  1. Collect gastric aspirate by nasogastric intubation or vomitus.  
  2. Place in tightly-sealed, sterile container and send to the laboratory promptly.

Additional Infomation

Many foods (e.g. incompletely cooked meat, raw fruits and vegetables, etc.) have peroxidase activity which can produce a positive gastroccult test result.  A fasting specimen is recommended.

Specimen Transport Temperature


Specimen Stability


Specimen Type Temperature Time
Gastric aspirate, occult blood Ambient 24 hours
  Refrigerated 5 days
Gastric aspirate, pH Ambient 30 minutes


Reference Values

pH: No established reference range

Occult Blood: Negative

Day(s) Test Set Up

Monday through Sunday

Test Classification and CPT Coding