Proficiency Testing/EQA / 2024 Surveys / Hematology and Clinical Microscopy / Clinical Microscopy Help Please log in to determine if you are eligible to purchase PT Programs. GASTRIC OCCULT BLOOD - GOCB Analytes/procedures in bold type are regulated for proficiency testing by the Centers for Medicare & Medicaid Services (CMS). Analyte Challenges pr Shipment Number of Shipments Gastric occult blood 3 Two shipments per year Gastric pH 3 Program Information Three 2.0‑mL simulated gastric fluid specimens Shipping Schedule Shipment A: February 12 Shipment B: September 3 Guest Log in/Register