Duodenoscope

Everything There Is To Know About Duodenoscopes

Overview

Duodenoscopes are special instruments that gastroenterologists and surgeons use to perform endoscopic procedures, especially ERCP (endoscopic retrograde cholangiopancreatography).

The major advantage of duodenoscopes is their side-viewing technology, which allows physicians to have a clear view of the main ducts of the gallbladder and pancreas.

The use of these instruments has revolutionized the field of gastroenterology since it offers a live video streaming at the smallest ducts of the digestive tract to confirm diagnoses, as well as perform simple procedures to alleviate any obstacles in those ducts.

In other words, a duodenoscope can be used as a diagnostic and therapeutic tool.

In this article, we will cover the history of duodenoscopes, indications, and some alternatives that offer the same value.

History of duodenoscopes

Humans were always obsessed about seeing what’s inside their bodies, which led to the invention of endoscopes.

The first instrument ever discovered dates back to the Greek era, with remnants of what seemed like an endoscope found in the ruins of Pompeii.

In 1805, a German doctor named Philipp Bozzini invented an instrument that was specifically designed to look inside the urinary tract, rectum, and pharynx. Philipp named this device a Lichtleiter (light-guiding instrument).

Jumping to 1853 when a French physician, Antoine Jean Desormeaux, designed a tube that goes inside the urinary tract and bladder and named it an endoscope.

After that, hundreds of doctors around the globe attempted to modify the design of endoscopes to come up with more efficient instruments for clinical use.

However, these devices all had a defective characteristic, which is inflexibility.

It wasn’t until 1932 when Dr. Rudolph Schindler invented the first flexible gastroscope that was later modified into various designs, including the duodenoscope that we know today.


Indications to use duodenoscopes

The primary use of duodenoscopes is ERCP, which helps diagnose several disease processes, including:


Gallstones

Gallstones have many types and could form anywhere in the gallbladder or bile duct. Subsequently, the normal flow of bile will get obstructed, leading to fluid stagnation, and eventually, bacterial infections.

If the stone clogs the main duct of the pancreas, it could lead to acute pancreatitis, which is an emergency that needs prompt medical care.

While gallstones are typically diagnosed, using radiological tests, such as abdominal X-ray and CT scan, some cases may not present with any indicative signs on imaging.

Therefore, physicians find themselves obliged to use ERCP, especially if the clinical suspicion is high.

Infections (e.g. cholangitis)

Several infectious pathogens can find their way into the bile duct, irritating the mucosal wall and causing local inflammation.

As a consequence, the bile duct might undergo what’s known as stenosis, which refers to the thickening of the duct’s wall and the reduction of its diameter.

This infection could also spread up-steam to destroy hepatocytes (i.e. liver cells), leading to jaundice and altered liver function tests (LFTs).

Similar to gallstones, some cases of cholangitis may require ERCP to confirm the diagnosis and start antibiotics.

Surgical complications of the pancreas or bile duct

Performing surgery on the pancreas, gallbladder, and bile ducts is a common practice for general surgeons.

Unfortunately, these operations are not without risk, and in some situations, a surgical complication may occur, which only manifests days after with clinical signs.

Using CT scan or MRI to identify the site of the complication may not give sufficient results, hence the need for ERCP to observe what went wrong.


Tumors of the bile duct

While this type of tumors is relatively rare, it is extremely aggressive, with a five-year survival rate of 30%.

Aside from its aggressiveness, this tumor is deadly because it is often discovered in late stages when the patient experiences signs and symptoms of bile duct obstruction.

Interestingly, the use of duodenoscopes for patients with high risk has been shown to be effective in reducing mortality rates since it allows surgeons and oncologists to act before it’s too late.


Acute pancreatitis

As the name implies, acute pancreatitis is an inflammation of the pancreas that occurs for a variety of reasons, including:

  • Obstruction of the pancreatic duct (e.g. gallstones, tumor)
  • Medications
  • Excessive alcohol consumption
  • Autoimmune disease
  • Idiopathic (unknown) origin

ERCP is not indicated in the case of acute pancreatitis unless the condition becomes recurrent without any evidence of the underlying cause.


Tumors of the pancreas

Tumors that affect the pancreas can be found in three locations:

  • Head of the pancreas
  • Body of the pancreas
  • Tail of the pancreas

When the tumor occurs in the head or body of the pancreas, it is easier to diagnose since the patient often presents with symptoms during the first stages of the disease.

This is due to the proximity of the tumor to the bile and pancreatic ducts, which may cause acute pancreatitis, biliary tract obstruction, and digestive symptoms.

However, if the tumor is located in the tail of the pancreas, it has a worse prognosis since there are no clinical signs until it has become too large for surgical ablation.

Gastroenterologists diagnose these tumors, using ERCP to visualize any masses in the pancreas and/or signs of ductal obstructions.


Complications of using duodenoscopes

Due to the design complexity of duodenoscopes, some experts suggest that post-procedural infections are iatrogenic in nature.

You see, these instruments have many small parts that are difficult to clean after ERCP. Obviously, doctors tend to reuse duodenoscopes for multiple procedures during the day, which increases the risk of developing an infection.

The Food and Drug Administration (FDA) described this phenomenon as reprocessing.

According to studies, the elevator mechanism is the part of the duodenoscope that’s most susceptible to carrying bacterial agents.

The American Gastroenterological Association released a paper, stating that “The problem of this infection transmission lies in the complex design of the elevator channel in duodenoscopes, which can allow bacteria to remain after cleansing, even if reprocessing follows currently accepted procedures developed and approved by the manufacturers and FDA.”

After assessing these findings, there are still no official statements about working on a new design to correct this problem.

This is mainly due to the inability to stop using duodenoscopes since their benefits outweigh the risks.


General specifications of duodenoscopes

There are several designs of duodenoscopes on the market, with different specifications; however, we are going to cite the general specifications, which should be accurate enough.

  • Field of view – 100 degree
  • Direction of view – 5’ retro-viewing
  • Depth of field – 5-60 mm
  • Distal End Diameter – 13.2
  • Flexible Portion Diameter – 12.5
  • Angulation range – up 120°, down 90°, right 110°, left 90°
  • Working length – 1240 mm
  • Total length – 1550 mm
  • Inner diameter – 4.2 mm
  • Minimum visible distance – 10 mm from the distal end


Conclusion

The invention of duodenoscopes was revolutionary for the fields of gastroenterology and general surgery.

This instrument provided us with several advantages, allowing physicians to confirm diagnoses and treat certain conditions in relatively delicate areas, such as the bile and pancreatic ducts.

Hopefully, you are more familiar with the benefits of duodenoscopes, as well as the common uses of these instruments.

If you still have any questions about duodenoscopes, feel free to ask in the comment section below.

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