HL7 Information 26
When searching for a medical software vendor, you will find that many providers offer HL7 compliant software. HL7 compliance means that the vendor is adhering to the requirements of the HL7 standard. However, in practice, true HL7 compliance does not exist, as the standardization becomes a challenge depending on the data structure.
By convention, a standard segment grammar notation is defined to provide a convenient way to indicate the segments that can be included in a particular type of HL7 message.
Many vendors use this segment grammar notation to specify what segments may be included with each type of HL7 message that they send.
The HL7 Delimiter Characters shown in the table below lists the default delimiter characters that are normally used in HL7 messages.
An HL7 message can choose to employ HL7 delimiter redefinitions.
If the standard characters are not convenient to use, the HL7 message can use different delimiter characters.
Each segment of an HL7 message consists of one or more composites (also known as fields). By default, the | (pipe) character is used to separate one composite from another.
A composite can be a primitive data type (such as a character string or a number), or can contain other composites.
If a composite contains other composites, these sub-composites (or sub-fields) are normally separated by ^ characters.
An important part of the HL7 standard is the ACKnowledgment protocol.
Every time an application accepts a message and consumes the message data, it is expected to send an ACKnowledgment message back to the sending application.
The sending application is expected to keep on sending a message until it has received an ACK message.
If you do not follow this rule, data may be lost in transmission.
This section describes the most common HL7 transport method used to send HL7 messages, called the Lower Layer Protocol (LLP). A less common HL7 transport called the Hybrid Lower Layer Protocol (HLLP) is also briefly discussed. Although HL7 messages are sent via a variety of TCP/IP transports, including FTP, SOAP and SMTP, LLP is the most common method.
n an HL7 message, each segment of the message contains one specific category of health information, such as patient information or patient visit data. The name of each segment in the message is specified by the first field of the segment, which is always three characters long.
Some message types support segment groups. An HL7 segment group is a collection of segments that always appear together. Depending on the scenario, some segment groups can be optional or repeating.
In this article, we will explore a typical sample HL7 message, and describe HL7 segments groups in detail.
HL7 is a messaging standard for data transfer and consistency across disparate systems, which plays a major role in healthcare interoperability. An HL7 message consists of one or more segments, which contains one specific category of information, such as patient information or patient visit data. Further, segments consists of one or more composites, also known as fields.