If you need to know how to detect leaks in an endoscope, something has probably already happened: a bubble that shouldn't be there, a blurred image after reprocessing, or a colleague saying that "the equipment feels weird." The short answer: it is detected with a leak test, that is, by pressurizing the equipment with the leak tester and observing it submerged in water or monitoring that the pressure holds. This guide explains how to do it, how to read the result, and what decision to make.

A small leak doesn't stay small. If liquid enters the internal channel, the problem stops being a part and becomes the entire equipment.

Why leaks occur in an endoscope

A leak in the endoscope almost always originates from a weak point in the insertion tube, the angulation section, or the control head seals. The most common causes are punctures from patient bites, impacts, sudden bends, wear of the rubber on the curved section, and seals that dry out over time.

In practice, damage rarely occurs from a single big blow. It is usually an accumulation: a fold when storing the equipment, forceps rubbing the rubber when exiting the working channel, a poorly placed ventilation cap during washing. Each event weakens the outer cover a little until a micro hole appears.

Other frequent sources are as follows:

• Bite on the insertion tube, especially in procedures without a bite block.
• Aging of the angulation rubber, which cracks or peels at the ends.
• Damage to the connector or the air and water valve, by pushing parts without aligning them.
• Pressure poorly applied when connecting the leak tester without the correct ventilation cap.
• Aggressive reprocessing, with unsuitable brushes or immersion without checking material compatibility.

Understanding the origin serves you for something concrete: when you find the leak, you will know if it is an isolated incident or a handling pattern that should be corrected in your service. But before pressurizing anything, it is advisable to look at what the equipment is telling you.

There is a nuance that is overlooked: an endoscope with leaks has not always been mishandled. The frequency of procedures, the type of patient, and the number of reprocessing cycles weigh as much as daily care. That is why learning how to detect leaks in an endoscope should not wait until a symptom appears, but rather be part of the service routine, especially when a piece of equipment accumulates many uses in a few weeks.

Warning signs before the test

The clearest prior signs of a leak in the endoscope are bubbles during immersion, liquid or moisture inside the connector, a blurred image or condensation spots, and an angulation section that loses precision or feels soft. If you see any, suspend use and perform the test before reprocessing.

An endoscopy nurse with years of experience usually detects these signs with her hands before her eyes. An insertion tube that gives in at one point, a slightly swollen area, or a different texture when sliding your fingers are real warnings. Always check under good light and with the equipment disconnected from the tower.

Quick visual and tactile inspection list:

1. Run your fingertips along the entire insertion tube looking for dents, swellings, or rough areas.
2. Look at the angulation rubber: look for cracks, bubbles under the rubber, or raised edges.
3. Check the distal head with a magnifying glass if possible: lens seals, adhesive edges.
4. Turn the angulation knobs and feel if there is abnormal play or irregular resistance.
5. Inspect the connector and the suction channel inlet for moisture or residue.

A blurred image deserves a separate mention. Sometimes it is confused with a video processor failure, and that is why it is advisable to rule out the equipment first. If you have doubts between an endoscope image problem and a tower problem, check the guide on endoscopy tower without image so as not to mix diagnoses.

Not all signs weigh the same. A moisture spot on the connector justifies checking it that same day, while a slight difference in the image may come from the tower or the lamp. Write down what you observed, at what point, and since when. That record helps you decide if the leak test is the next step or if it is advisable to check the image system first.

How to detect leaks in an endoscope: step-by-step leak test

To detect leaks in an endoscope, the leak test consists of connecting a tester to the equipment, pressurizing the interior, and checking that the pressure remains stable. It can be done dry to verify the pressure and wet, with the endoscope submerged, to see exactly where the air escapes.

Before starting, check the manual of your model. Each manufacturer defines the test connector, the applied pressure, and the times. What follows is the general flow that is repeated in most flexible equipment, including the Olympus endoscopy line, but your manufacturer's protocol rules.

Preparation

• Perform the test with the endoscope disconnected from the tower and without the light source.
• Verify that the leak tester works: that it generates pressure and that the manometer responds.
• Have clean water at hand in a wide container, large enough to submerge the tube without forcing curves.
• Use gloves and protection according to your biosafety protocol.

Dry leak test

1. Connect the tester to the ventilation port of the endoscope, ensuring the seal.
2. Pressurize up to the value indicated by the manufacturer, never above.
3. Wait the recommended time and observe the manometer. A sustained drop in pressure indicates a leak.
4. Check that the insertion tube inflates evenly and that the angulation rubber tightens without deforming.

How to detect leaks in an endoscope wet

1. With the equipment pressurized, submerge it completely in the water.
2. Move the angulation section in all directions: some leaks only appear when flexing.
3. Move along the tube calmly, from the control head to the distal end. Observe for at least one minute in each section.
4. Pay attention to the sensitive points: tube-control union, angulation rubber, distal lens, and connector.
5. If you see a continuous or intermittent stream of bubbles, mentally mark the point of origin before taking it out.

A note on pressure: the question "what pressure to use?" does not have a universal figure. Each manufacturer's leak tester is calibrated for their range of equipment, and using nitrogen or another gas at workshop pressure on an endoscope can burst the angulation rubber. Use only the tester and the value indicated in the manual.

Interpretation of results

If the pressure holds and no bubbles appear, the equipment passes the test. If the pressure drops or bubbles are seen, there is a leak and the equipment should not be used or submerged further. The pattern of the bubbles tells you where to look: constant ones usually indicate a puncture; intermittent ones, a seal or a joint that gives when flexing.

The typical doubt is what to do when nothing is seen but the pressure drops. There several possibilities: a micro hole that only releases tiny bubbles, a connector seal that is not properly seated, or a tester connection that did not close well. Before blaming the endoscope, disconnect, reconnect, and repeat. Ruling out the assembly error saves you a false diagnosis.

To locate a leak that is not seen, it helps to take the equipment out of the water with the pressure still active, dry it with a cloth, and check with grazing light. A drop that always reappears at the same point gives away the origin. If you suspect that liquid has already entered, do not store it either: trapped moisture worsens the damage over time.

When you already have a result, compare it with the last recorded test of the same equipment. A pressure that drops a little more each month indicates progressive wear, even if today it still passes the test. That trend gives you time to schedule the service before the equipment is out of use in the middle of the shift. It is one of the data points that is most lost when there is no record.

What to do if the endoscope has a leak

If the endoscope has a leak, remove it from use immediately, do not submerge it in disinfectant or run it through the automatic washer, identify the equipment with a visible label, and report the finding. An equipment with a leak that enters reprocessing can flood inside.

The practical sequence, in order, is this:

1. Stop use and remove the endoscope from the clean area so that no one takes it by mistake.
2. Perform the manual pre-cleaning according to the protocol if it has already been in contact with a patient, without complete immersion. Follow the manufacturer's instructions for equipment with confirmed leaks.
3. Dry the exterior and leave the equipment in a transport case, not in the usual storage case.
4. Record the event: date, serial number, description of what was observed, who performed the test, and what type of leak was seen.
5. Inform the person in charge of the service and biomedical engineering to decide the repair route.

The record seems like bureaucracy, but it is what allows you to detect patterns. If three pieces of equipment from the same service come out with a leak at the same point of the tube, the problem is not the equipment: it is a handling step. Having that history also serves you when talking to the supplier.

A repeated error: trying to "seal" with glue or tape. Do not do it. An improvised patch can hide the leak in the next test and leave the patient exposed to an unreliable piece of equipment.

Common errors when detecting leaks in an endoscope

The most expensive error is submerging the equipment before pressurizing it. Without pressure, bubbles do not appear, and the result remains "it looks good" when in reality no one looked with criteria. That is why the wet test always starts with the equipment already pressurized and with the manometer in view.

The second error is confusing a bubble from the system with a real leak. When taking the tube out of the water, sometimes air remains trapped in the working channel or under the ventilation cap. Dry the surface, let it rest for a moment, and observe again. If the bubble reappears at the same point, it is no longer trapped air.

The third error is raising the pressure above the manufacturer's value "to make sure." Excessive pressure can open a leak that did not exist or damage a rubber that was healthy. When the test fails, the correct thing is to repeat it with the indicated value and not increase the pressure.

When to send it to technical service

Send the endoscope to technical service whenever the leak test is positive, when the pressure does not hold after repeating it, or when there is liquid inside the equipment or visible damage in the angulation rubber. A confirmed leak is not repaired in the service: it requires disassembly, part replacement, and subsequent verification.

The sooner it arrives, the better. A leak addressed in time can mean replacing a rubber or a seal. An ignored leak, with water inside the tube, can damage fibers, the image sensor, or the angulation cables. 

When you contact the workshop, have the following ready:

• Brand, model, and serial number of the endoscope.
• Test result and in what area the bubbles were seen.
• If the equipment was submerged or run through the washer with the leak present.
• Recent history of repairs and maintenance.

So that you do not depend on surprise, integrate the leak test into each reprocessing cycle and in your routine of preventive maintenance of endoscopes. The general reference about endoscopes on Wikipedia serves to contextualize the equipment, but the exact procedure is always defined by the manufacturer's manual.

Your next step: take today the endoscope that is most used in your service, perform the complete leak test with the tester, and record the result. If something makes you doubt, repeat the test and consult with a technician before the next procedure.

Frequently asked questions

How is the leak test performed on an endoscope?

The leak tester is connected to the ventilation port of the endoscope, pressurized to the value indicated by the manufacturer, and it is observed that the manometer does not drop. Then the equipment is submerged in water, the angulation is flexed, and bubbles are searched along the tube, the rubber, and the control head.

How to locate a water leak that is not seen?

Keep the equipment pressurized, take it out of the water, dry it with a cloth, and check with grazing light: a drop that always reappears at the same point marks the origin. It also helps to repeat the wet test by flexing the angulation, because some leaks only open with the movement.

What nitrogen pressure to detect leaks?

In a flexible endoscope, nitrogen or gas at workshop pressure is not used. You must use only the manufacturer's leak tester, which is calibrated for that model. Excessive pressure can burst the angulation rubber, so always check the exact value in the equipment manual.

How to know where a leak in an endoscope comes from?

Submerge the pressurized endoscope and observe the origin of the bubbles. If they come continuously from the tube, it is usually a puncture; if they appear when flexing, the angulation rubber; if they come from the control head, a seal or valve. Repeat the test to rule out a poorly adjusted tester connection.

How often should I perform the leak test of the endoscope?

The usual practice is to do it in each reprocessing cycle, before immersion, and whenever you see warning signs. The exact frequency is defined by the manufacturer's manual and your institution's protocol, so confirm it with biomedical engineering or infection control.

Can I continue using an endoscope with a small leak?

No. A small leak allows liquids to enter the interior and can damage fibers, sensor, and mechanisms, in addition to compromising patient safety. Remove the equipment from use, identify it, record it, and send it to technical service for repair and verification.