This value set includes codes based on the following rules:

• Include these codes as defined in http://snomed.info/sct version http://snomed.info/sct/731000124108/version/20201118

  Code	Display
  87612001	Blood
  80891009	Heart structure
  39607008	Lung structure
  45206002	Nasal structure
  71836000	Nasopharyngeal structure
  54066008	Pharyngeal structure
  3120008	Pleural membrane structure
  2748008	Spinal cord structure
  281778006	Intrathoracic lymphatic structure

• Include these codes as defined in http://terminology.hl7.org/CodeSystem/v3-NullFlavor version 20090501

  Code	Display
  OTH	Other specimen source site (specify)
  UNK	Unknown