Healthcare IT Decoded – It’s a Train !!

“It’s a bird; it’s a plane!! “No, no, it’s a train!!”

“Huh, Train? What are you talking about?”

“The data in the file, from far it, looks like a train,” mentioned Yaksha, looking at the monitor, which had some unreadable data, but the pipe characters were distinctly clear.

“Oh, that, it’s an HL7 train,” I exclaimed, standing near my junior team member, watching him scratch his head.

“HL what?”

“Seven, HL7, also known as Health Level Seven.”

“You know I respect you, but that sounds completely gibberish,” Yaksha exclaimed, looking at me as though I was speaking a foreign language.

“Hahaha!! Well, that’s how I felt when I heard it for the first time way back in 2008,” I calmly replied with a smile, pulling a nearby chair and getting seated comfortably.

We were seated in a square cubicle in one corner of the office floor. Our bay had space for four people to sit comfortably, two on either side.


Additionally, the area was next to a gigantic black printer, so we were privy to constant whirring sounds.

Yaksha was a curious fellow, always asking questions. One could predict what he would ask next as he politely inquired, “What is this HL7?”

“Simply put, a standard of communication,” I responded, with my hands resting on the side arms of the five-wheel revolving chair.


“Yes, Standard, a structured way of communication!!”

“Okay, you aren’t making sense again!!”

“Haha, okay, lets me try this one more time.”

Yaksha swiveled his chair, crossed the fingers of his right hand, and looked at me as I asked him, “Do you know which are the most commonly spoken languages in the world?”

“Hmm, English, Hind, Spanish,” he replied, counting the same one by one on his left-hand fingers.

“Yes, we have Mandarin, Arabic, and many more.”

“But how’s it related?”

“You see, people speak to each other in English, Hindi, or any other language. Similarly, One hospital system can talk to another using HL7.”

“Ohh, Interesting Analogy!!” mentioned Yaksha raising his right eyebrow.

I nodded in agreement as he stated, “Tell me more about this HL eight.”

“Seven, HL Seven,” that’s how it’s pronounced.

Yaksha corrected himself and said, “Okay, HL7, I want to know more.”

 “So, let’s look at the data you have in the file,” I stated while driving my chair closer to Yaksha’s desk.

The data had many pipe characters, some caps (carrot character), and various alphabets. So, I copied the data into an excel file and delimited the data using a pipe character.

“Voila!!” I exclaimed, “Does the data look readable now?”

“Yes, very much, it makes some sense,” Yaksha replied, raising both his eyebrows this time around.

“You see the first three characters?”

“Hmm, Yes.”

“That indicates what information is sent in that line.”


“So, the first line is MSH; it gives me the address information, like the sender and receiver.”

“Okay, but what are we sending?”

“Mostly Patient information, for example, sending data to Admit a Patient, ordering a lab test, or sending the results of a test.”

“Hmm, but how will I know what data is being sent?”

“The First Line itself!!”

“Oh, but where?” asked Yaksha with his eyes peering through the excel file, looking for answers.

“Alright, let’s do some counting,” I said as we moved nine cells to the right and saw some peculiar-looking data.

“Well, this looks like a code to crack,” exclaimed Yaksha as we stopped at a cell that read ‘ADT^A04.’

“Ya, but it’s simple; here, instead of a pipe, we have a cap separating two data elements,” I explained, copying the data and segregating it into ADT and A04.

“And, what do these two mean or imply?”

“Well, the first one, i.e., ADT, is the message type indicating Admit Discharge Transfer.”

“That sounds logical!!”

“Yes, it is. Similarly, there are many other messages, ORM for Orders, ORU for results, and many more.“

“And what about the second data element?”

“They are called, Trigger Events,” I replied.

“Huh, you just threw a new jargon in the mix,” stated Yaksha with his palm on his forehead.

“Hahaha, don’t worry, this one is relatively straightforward,” I mentioned with a smile.

“Let’s see.”

“These are real-world events related to each message!!”

“Huh, okay, can you give an example?”

“Yes, sure, A04 here means Register a patient.”

“Nice, but are there more like these?”

“Absolutely, A01 is Admit the patient, A03 is Discharge the patient.”

“So these are all related to admissions?”


“So how can we send Lab results?”

“We can do that using ORU R01 which is an observation message,” I replied.

“That’s so cool, what are these PID, AL1 etc.?” inquired Yaksha pointing towards the first column in the excel sheet.

“Each line is called a segment, PID refers to Patient Identification, AL1 to Allergies, like these there are segments for all kinds of information that can be captured.”

“This is so structured, isn’t it?”

“Well, that’s why they call it a standard!!”

“Where can I know more about some of these standards?”

“You can grab a copy of my book Healthcare IT Decoded or Amazon or check out my course on Udemy.”

My Course on Udemy