How can I use a Mirth-Javascript to remove line breaks in HL7 messages?

Question

An HL7 message comes into Mirth and throws a "processing" error. At the very bottom of the message in Raw format is a partial line that has been separated from the line above it. I have to manually correct this every time. I am hoping to use a Mirth-Javascript as a message filter that can fix this so that everything flows without human intervention.

Below message snippet triggers the error. In this example it is the very last line of the HL7 message.

OBX|68|FT|PT6663&IMP^PET/CT Imaging Whole Body||

||||||F|||202254836969552|||

Currently my only fix is to open the HL7 message and manually go to the line break and bring it up to the line above it that is part of the segment.

The HL7 message should look like this:

OBX|68|FT|PT1103&IMP^PET/CT Imaging Whole Body||||||||F|||20190327101958|||

Answer 1

This worked. Put the following into the preprocessor.

message = message.replace(/[\r\n]+(?![A-Z][A-Z][A-Z0-9]\|)/g, "");

return message;

Answer 2

Remove all line brakes in the channel's pre-processor or attachment script, and then insert them back based on the segment names. The best way would be to stop the message generating system insert line brakes into OBX.5 field.

Answer 3

From your question, the HL7 field that contains line breaks is OBX(5,1) which should hold Observation Value.

Observation value may contain line breaks as a part of data. Line break ( <CR> or ASCII 13 ) is segment separator by default. If this is received as a part of data, there will be issues while parsing message. This is the root cause of the problem you mentioned in the question.

The segment separator is not negotiable . It is always a carriage return. I have explained this in more details in this answer.

Ideally, those line breaks should be replaced with its escape sequence while building HL7 message. More details about it are already given in one of my earlier answers here .

So, your inbound message

OBX|68|FT|PT6663&IMP^PET/CT Imaging Whole Body||

||||||F|||202254836969552|||

should be actually

OBX|68|FT|PT6663&IMP^PET/CT Imaging Whole Body||\X0D\\X0D\||||||F|||202254836969552|||

About your actual question that how to do this with Mirth/Javascript, there should not be need in your particular use case. This conversion should be done before sending message to Mirth. So, the one who is sending this message to you should build it like this.

While actually displaying observation value on UI, you again need to do the reverse process.

Edit:

If line break is different than <CR> (ASCII 13), then respective HEX should be replaced in \\X0D\\ . Details are mentioned in my linked answer; I am not repeating those here.

Answer 4

Removing all line breaks would be an approach, but it could be a problem later on, you could set up a replace script, that instead of '/n', searches for '|/n|' or a similar string, that way, it would fix that particular problem as well as any other undesired line breaks in between vertical separators, tho it wouldnt help if it broke anywhere else, so keep that in mind.

Answer 5

Put this code snippet in your preprocessor script. It worked for me

var newmessage = message.replace(/[\n\r]$/,"");

while (newmessage.match(/(\r\n|\r|\n)([^A-Z]|[A-Z][^A-Z]|[A-Z]{2}[^A-Z\d]|[A-Z]{2}[\d][^|]|[A-Z]{3}[^|])/i)) {
    var extrabit = newmessage.match(/(\r\n|\r|\n)([^A-Z]|[A-Z][^A-Z]|[A-Z]{2}[^A-Z\d]|[A-Z]{2}[\d][^|]|[A-Z]{3}[^|])/i)[0].substring(1);
    var newmessage = newmessage.replace(/(\r\n|\r|\n)([^A-Z]|[A-Z][^A-Z]|[A-Z]{2}[^A-Z\d]|[A-Z]{2}[\d][^|]|[A-Z]{3}[^|])/i,'\\.br\\' + extrabit);
}

return newmessage;

Answer 6

Mirth processor expects every line the first 3 characters should contain valid HL7 segments otherwise the mirth throws an error.

To remove the invalid line breaks in the HL7 message you should follow the below steps.

1.Channel -->Scripts -->Preprocessor.

2. Paste the bellow code top of the "return message;" statement message = message.replace(/[\\r\\n]+(?![AZ][AZ][A-Z0-9]\\|)/g, ""); //This Line is for invalid line breaks in incoming message APPEND to PREVIOUS SEGMENT .
3. Save the changes and deploy the channel for new changes affected.

Answer 7

I had the similar issue of having blank lines between the segments and i solved it liked this :

content = content.replace(/^\s*\n/gm, '');

Note: This will just remove blank lines. You need to still figure out how to get the next line on current line

You can try regex to eliminate all '\\n' not followed by any segment.