Skip to main contentLast updated: 14-Nov-2026
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Dr Harsh Shah
MS, MCh (Surgical Gastroenterology), DrNB (Surgical Gastroenterology)
Registered with Gujarat Medical Council, Reg. No. G-38738
Food Pipe & Gastro Surgeon
Dr. Jivraj Mehta Hospital, Vasna, Ahmedabad · 18 years of experience
In short
The Chicago Classification is the rule book for reading a food pipe pressure test. It asks two questions in order: does the lower valve open, and how does the pipe squeeze?
A valve that does not open points to achalasia or a near cousin of it. A valve that opens, with a strange squeeze, points to a spastic or weak pipe.
The report alone never decides treatment. It is read with an endoscopy, a barium film and your own symptoms.
For the full picture of achalasia, from tests to the choice between POEM and Heller operation, read our achalasia treatment page. This post explains only how the pressure report is read.
It is the shared rule book that doctors across the world use to read a high-resolution manometry tracing. It turns a page of colours and numbers into one named pattern.
The test is simple to describe. A thin tube with many pressure sensors rests across your food pipe. You swallow about ten small sips of water. A computer draws the pressure as a colour map.
The map alone is hard to read. The Chicago Classification gives the steps and the cut-off numbers. Because every centre follows the same steps, two doctors reading the same tracing should reach the same name.
The rules have been revised several times. The current version is the fourth. It also asks for extra swallows, such as a quick drink of water, to see how the pipe copes under load.
Four numbers do most of the work. One tells you about the valve, and the rest tell you about the squeeze of the pipe above it.
| Measure | What it shows | What an odd value suggests |
|---|---|---|
| IRP (integrated relaxation pressure) | How well the lower valve opens during a swallow | A high value means the valve is not opening fully |
| DCI (distal contractile integral) | How strong the squeeze of the lower pipe is | Very low means a weak pipe, very high means a forceful one |
| DL (distal latency) | How soon after the swallow the squeeze reaches the lower pipe | A short delay means a premature, spastic squeeze |
| Pressurisation | Whether the pipe fills and squeezes against the closed valve | Seen in one type of achalasia |
Cut-off values differ a little between machine makers, so your report states its own limits. Do not compare your numbers with a friend’s report from another centre.
They read it in two steps. First they look at the valve. Only then do they look at how the pipe squeezes.
The last step matters most. A tracing is only a snapshot of one morning. A name on a report is a working label, not a final verdict.
A valve that stays tight is the key finding. It puts the report in the obstruction group, and achalasia is the main member of that group.
Achalasia has three types, named I, II and III, by what the pipe above the valve does. We explain them in a separate post, achalasia types I, II and III and why the type matters.
Some people have a tight valve but a squeeze that does not fit any of the three types. Doctors call this outflow obstruction at the valve. It has several causes. Some are mild or short-lived. A few are an early form of achalasia. A growth near the valve can also look the same.
Treatment is chosen only after these checks. It is not chosen from the pressure number alone.
When the valve opens normally, the problem lies in the squeeze of the pipe. The report then names a spastic, weak or absent pattern.
Each of these can look similar to heart pain or reflux, so a heart check and an endoscopy are done first. Treatment is aimed at your symptoms. For many people, medicines and diet advice come first. A procedure is considered only if symptoms stay severe.
No. Many people have a mild oddity on a pressure test and few or no symptoms. The report is a tool for explaining symptoms, not a reason for treatment on its own.
Doctors treat the person, not the tracing. A mild weak squeeze in someone with no swallowing trouble is usually left alone. A tight valve in someone who vomits undigested food and is losing weight needs action.
If your report names a pattern that looks serious, do not panic. Many patterns are managed with simple steps. Some, like achalasia, have good treatment options. The right first step is to have all your tests read together by one surgeon or gastroenterologist.
Dr Harsh Shah does laparoscopic and open surgery. If POEM or balloon dilation suits you better, the plan is made with the endoscopy team. This is done after your reports are reviewed.
Bring the full printed report with the colour maps, not only the summary line. Bring your endoscopy and barium films too.
Call us soon if you cannot swallow even saliva. Call soon too if you are losing weight fast, or if food goes into your breath and causes cough or chest infection. These need a prompt review, not a wait for the next appointment.
It is a set of rules that doctors use to read a high-resolution manometry tracing of the food pipe. It first checks whether the lower valve opens. It then checks how the pipe squeezes, and names the pattern.
Manometry is a pressure test. A thin tube with many sensors is passed through the nose into the food pipe. You swallow small sips of water. It takes a short time, needs no anaesthesia and is generally well tolerated.
IRP stands for integrated relaxation pressure. It shows how well the lower valve opens when you swallow. A high value means the valve is not opening fully.
Not always. Achalasia is one of several patterns. The report is read with an endoscopy and a barium swallow, and with your symptoms, before a name is given.
It is a pattern with very strong squeezes of the food pipe, which can cause chest pain and trouble swallowing. The valve opens normally. It is one of the spastic patterns in the classification.
It means the squeezing is weak, so food moves down slowly. It is common and often found with acid reflux. It needs treatment only when it causes symptoms.
See a doctor soon if you cannot swallow even saliva or are losing weight fast. Also go if food goes into the breath and causes cough or chest infection. These need a prompt review.
For the full picture of achalasia and its treatment, start at the achalasia treatment page. For questions before you travel, call +91-63555-64601.
Dr Harsh Shah — Dr. Jivraj Mehta Hospital, Vasna, Ahmedabad
Dr. Jivraj Mehta Hospital, Dr Jivraj Mehta Marg, Vasna, Ahmedabad 380007.
Consultations, review of reports and scans, operations and follow-up. OPD Monday to Saturday, 9 am to 5 pm.
Appointments: +91-63555-64601 · +91-63590-11009 · Hospital 079-2663 6363
Directions to the hospital · WhatsApp +91-63555-64601
Handed a manometry report full of numbers and a long medical name? Dr Harsh Shah, a food pipe and gastro surgeon in Ahmedabad, reads these reports with patients every week. Bring the printout, your endoscopy and your barium film. He will tell you in plain words what the tracing shows. You can also call us or write on WhatsApp. Call For Appointment Book on WhatsApp Tapping Book on WhatsApp will likely open the WhatsApp app on your phone.
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