Anyone who has worked in the world of healthcare integration or with HL7 knows that if you have seen one HL7 message, you’ve seen one HL7 message. Now, a common problem with some source systems is that a line break will sneak in the middle of a segment, rendering the whole message invalid. How many times have you seen this message?
MSH|^~\&|DDTEK LAB|ELAB-1|DDTEK OE|BLDG14|200502150930||ORU^R01^ORU_R01|CTRL-9876|P|2.4
PID|||010-11-1111||Estherhaus^Eva^E^^^^L|Smith|19720520|F|||256 Sherwood Forest Dr.^^Baton Rouge^LA^70809||(225)334-5232|(225)752-1213||||AC010111111||76-B4335^LA^20070520
OBR|1|948642^DDTEK OE|917363^DDTEK LAB|1554-5^GLUCOSE|||200502150730|||||||||020-22-2222^Levin-Epstein^Anna^^^^MD^^Micro-Managed
Health Associates|||||||||F|||||||030-33-3333&Honeywell&Carson&&&&MD
OBX|1|SN|1554-5^GLUCOSE^^^POST 12H CFST:MCNC:PT:SER/PLAS:QN||^175|mg/dl|70_105|H|||F
Notice the “Health Associates” segment? Obviously, this segment invalidates the message. When this message is sent through a Mirth channel that expects incoming HL7, the message will error out when Mirth tries to parse it. Here is how we can fix that.
To fix this, we’re going to use a channel’s preprocessor script to append seemingly broken segments to the previous segment. Since the preprocessor script is invoked before Mirth’s HL7 parser, we don’t have to worry about Mirth’s HL7 parser choking on it.
Instead of explaining the logic in a separate paragraph, I have left inline comments to explain what is happening. I think, though, that it is fairly easy to follow.
Paste the following code into your channel’s preprocessor script.
The Code
// initialize a first_iteration flag.
// we don't want to add a carriage return
// before the MSH segment
var first_iteration = true;
// initialize the new message as an empty string
var new_message = '';
// loop over each line in the message
// by splitting on the hl7 standard carriage return
for each (var line in message.split(/\r/)) {
// if it is a valid hl7 segment, we'll
// append the new line to the new message
if(line.match(/^[a-zA-Z0-9]{3}\|/)) {
// see the first comment
if( ! first_iteration){
new_message += '\r';
}
new_message += line;
} else {
// if it isn't a valid hl7 segment,
// we'll append it to the end of the
// previous segment instead
new_message += ' ' + line;
}
// it will never be the first_iteration again
first_iteration = false;
}
//send the fixed message to the channel
message = new_message;
return message;