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Appendix H: LOINC
Two kinds of measures are of interest. The "absolute" number of such cells per cubic millemeer. These are represented as
number concentrations, e.g.,:
Lymphocytes.CD10+CD20+NCNC:PT:BLD:QN
The other quantity of interest is the percent of these cells per 100 lymphocytes. These are represented as number fractions,
e.g.:
Lymphocytes.CD10+CD20+100 lymphocytes:NFR:PT:BLD:QN
The database also includes fully specified names for all of the commonly reported HLA antigens. These are grouped in the
class HLA. Experimental methods can define many subtypes of many antigens, so this list is not exhaustive, and is also
likely to expand with time.
Example:
HLA-A1:ACNC:PT:BLD^PATIENT:ORD
3.4
Naming results of microbiological culture
The inherent complex structure of results of microbiological culture presents unique challenges for standard names.
Result Status (Preliminary, Final) will be indicated in the OBR segment of HL7 segment with the Result Status field
(OBR-25), not as part of the name.
Specimen Type (Serum, Blood, Urine, etc.) will be indicated in the HL7 OBR segment with the Specimen Source field
(OBR-15), but may also be represented in the name.
Details of specimen collection will usually be noted as OBX segments or comment segments that accompany the culture
result message. The observation identifier for the OBX segment will have the fully specified name of "Specimen
Collection Description:NOS:NOMS" and the Observation Sub-ID field will be used to order or group sets of observations.
That is, if the material was collected by swabbing a wound of the right upper arm, multiple OBX segments would be
created, each with the name "Specimen Collection Description:NOS:NOMS," and the Observation Results fields of the
OBX segments would contain respectively "Swab," "Right," "Arm," and "Wound." (The granularity of the actual terms
used in the specimen description is at the discretion of the user. Thus, "Right Arm Wound" as the value of a single OBX
segment could be used in place of the three codes described in the previous sentence.)
Descriptions of measurement and culture growth will be noted as separate OBX segments that accompany the culture
result message. The name of the observation identifier will provide the context of the observation. For instance, the name
for a quantitative test of bacteria in a specimen would be:
COLONY COUNT:NUM:PT:XXX:QN:VC
Descriptions of Gram stain findings will be noted as OBX segments that accompany the culture result message. The name
of the observation identifier will be:
MICROSCOPIC OBSERVATION:PRID:PT:XXX:NOM:GRAM STAIN
The result values that could be reported with this test (which is a multiple-choice, multiple answer type or observation)
might include one or more of the following:
Epithelial cells
Gram positive cocci in chains
Many Gram negative diplococci
The organisms identified in a culture will be sent as result values in OBX segments. A separate table of allowable
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organism names will need to be identified. Bergey's Manual of Determinative Bacteriology or some other authoritative
Page H-34
Final Version 6/98
Health Level Seven Implementation Support Guide
for HL7 Standard Version 2.3 1998. All rights reserved.