[Code of Federal Regulations] [Title 21, Volume 8] [Revised as of April 1, 2008] From the U.S. Government Printing Office via GPO Access [CITE: 21CFR864.6550] [Page 240] TITLE 21--FOOD AND DRUGS CHAPTER I--FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) PART 864_HEMATOLOGY AND PATHOLOGY DEVICES--Table of Contents Subpart G_Manual Hematology Devices Sec. 864.6550 Occult blood test. (a) Identification. An occult blood test is a device used to detect occult blood in urine or feces. (Occult blood is blood present in such small quantities that it can be detected only by chemical tests of suspected material, or by microscopic or spectroscopic examination.) (b) Classification. Class II (performance standards). [45 FR 60606, Sept. 12, 1980]