Draft Website - For Review Purposes Only

The Technical Steward for the OM3 segment is Orders and Observations.

This segment applies to free text and other non-numeric data types.

HL7 Attribute Table - OM3 - Categorical Service/Test/Observation Segment

Seq#	DataElement	Description	Must Implement	Flags	Cardinality	Length	C.LEN	Vocabulary	DataType
OM3
1	00586	Sequence Number - Test/Observation Master File		=	[0..1]		4		NM
2	00636	Preferred Coding System			[0..1]			0650	CWE
3	00637	Valid Coded "Answers"			[0..*]			0652	CWE
4	00638	Normal Text/Codes for Categorical Observations			[0..*]			0654	CWE
5	00639	Abnormal Text/Codes for Categorical Observations			[0..*]			0655	CWE
6	00640	Critical Text/Codes for Categorical Observations			[0..*]			0656	CWE
7	00570	Value Type			[0..1]	[2..3]		0125 Value Type	ID

(Definition from OM1.1 in Ch. 8)

Definition: This field contains the first OM1 segment in a message and is described as 1, the second as 2, and so on.

(Definition from OM2.1 in Ch. 8)

Definition: This field contains the same value as the sequence number of the associated OM1 segment. Refer to Table 0648 - Units of Measure in Chapter 2C for valid values.

(Definition from OM3.1 in Ch. 8)

Definition: This field contains the same value as the sequence number of the associated OM1 segment.

(Definition from OM4.1 in Ch. 8)

Definition: The OM4-1 contains a numeric value that indicates a unique set of OM1, OM2, OM3, and OM4 components; each OMn-1 in a set will have the same value as illustrated in the example below. Because the OM4 segment can repeat, but needs to have a unique number for use with OM4-17, the sequence number must be appended with a sequence number as shown in the second example below.

OM4-1 Sequence Number – Test/Observation Master File Example:

MSH|...<cr>

// start MFE Test Begin group

MFE|A|...<cr>

OM1|1|...<cr>

OM2|1|...<cr>

OM3|1|...<cr>

OM4|1|...<cr>

// end MFE Test Begin group

// start MFE_Test_Begin group

MFE|A|...<cr>

OM1|2|...<cr>

OM2|2|...<cr>

OM3|2|...<cr>

OM4|2.1|...<cr>

OM4|2.2|...<cr>

//end MFE_Test_Begin group

(Definition from OM5.1 in Ch. 8)

Definition: This field contains the same value as the sequence number of the associated OM1 segment.

(Definition from OM6.1 in Ch. 8)

Definition: This field contains the same value as the sequence number of the associated OM1 segment.

(Definition from OM7.1 in Ch. 8)

Definition: This field contains the same value as the sequence number of the associated OM1 segment.

(Definition from OMC.1 in Ch. 8)

Definition: This field contains the same value as the sequence number of the associated OM1 segment.

Definition: This field contains the observations whose categorical responses are taken from a specified table of codes (e.g., CWE data types). Record the preferred coding system for these responses as observations (e.g., ICD10, HGVS, ISCN, SNOMED CT). Refer to Table 0650 - Preferred Coding System in Chapter 2C for valid values.

Definition: This field contains a list of valid coded answers. In the case that the list of coded answers is easily enumerated, list the valid coded answers for this observation here using the preferred coding system given in OM3-2 - Preferred Coding System. If, for example, the given observation was VDRL, the valid answers might be "non-reactive", "86^ intermediate", and "87^ reactive".Refer to Table 0652 - Valid Coded "Answers" in Chapter 2C for valid values.

Definition: Certain observations/tests with a nature code of A or C (see OM1-18 - Nature of Service/Test/Observation) have text (alpha) results (e.g., reactive, nonreactive). Alpha normals for those tests should be entered in this field (e.g., "nonreactive"). Refer to Table 0654 - Normal Text/Codes for Categorical Observations in Chapter 2C for valid values.

The format of this field is:

The first component is a code taken from a standard code source list. The second component is the text associated with the code. The third component is the identification of the code table source. When only a text description of a possible answer is available, it is recorded as ^<text>.

Care should be taken to transmit only those results that are considered normal for that test. A drug screen may have possible results of "negative" and "positive." However, only a result of "negative" is considered to be normal. When an observation has more than one "normal" result, multiple values in this field should be separated with a repeat delimiter.

Definition: This field contains the list of the text answers that are abnormal for the test. Refer to Table 0655 - Abnormal Text/Codes for Categorical Observations in Chapter 2C for valid values.

Definition: This field contains the list of coded results that are critically abnormal for this observation. Refer to Table 0656 - Critical Text/Codes for Categorical Observations in Chapter 2C for valid values.

(Definition from OBX.2 in Ch. 7)

Definition: This field defines the data type of OBX-5, Observation Value. If OBX-5, Observation Value, is valued then OBX-2, Value Type, SHALL be valued. When OBX-5, Observation Value, is not valued, OBX-2 Value Type MAY be valued to represent a data type used to value the observation expressed in OBX-3, Observation Identifier. See HL7 Table 0125 – Value Types for valid values.

Condition: This field is required if OBX-5, Observation Value, is valued.

For example, if the value is 'CWE' then the result in OBX-5 must be a coded entry or text or both. As of v 2.7, the ST data type may not be used to transmit data that can be more precisely transmitted using other data types, e.g. SN when comparative symbols are needed.

The RP value (reference pointer) must be used if the OBX-5 contains a pointer to the data e.g., a URL of an image. The receiving system can use this reference pointer whenever it needs access to the actual data through other interface standards, e.g., DICOM, or through appropriate data base servers.

The structured numeric (SN) data type provides for reporting ranges (e.g., 3-5 or 10-20), titres (e.g., 1:10), and out-of-range indicators (e.g., >50) in a structured and computer-interpretable way.

We allow the FT data type in the OBX segment, but its use is discouraged. Formatted text usually implies a meaningful structure, e.g., a list of three independent diagnoses reported on different lines. But ideally, the structure in three independent diagnostic statements would be reported as three separate OBX segments.

TX should not be used except to send large amounts of text. In the TX data type, the repeat delimiter can only be used to identify paragraph breaks. Use ST to send short, and possibly encodable, text strings.

CDA documents are to be exchanged in the OBX segment in any message that can exchange documents (such as MDM or ORU). Within the OBX segment, the MIME package is encoded as an encapsulated (ED) data type.

(Definition from OM3.7 in Ch. 8)

Definition: This field contains the allowed data type for a single categorical observation (code A or C in OM1-18 - Nature of Observation). Refer to HL7 Table 0125 – Value Type in Chapter 2C, Code Tables, for valid values.