Contact Endoscopy in ENT

What is Contact Endoscopy?

Contact endoscopy with narrow-band imaging is a noninvasive OPD procedure rarely used in India. However, it can provide preoperative information that is both safe and helpful. Therefore, it is significant to understand when, where, and how to use contact endoscopy.

This procedure can help determine whether a tumor is benign or malignant and provide information about its surface microstructure, microcirculation, and vascular anatomy. This information is crucial for understanding the progression and invasion of laryngeal tumors.

Compared to methods such as the naked eye or with a loop magnification of 2x-5x used 25-40 years ago, endoscopy provides a panoramic view and tissue architecture that gives a better understanding of the tissue microstructure in a noninvasive way. While it is not a replacement for biopsy, it can provide valuable information about what is being dealt with preoperatively.

Detailed overview of Contact endoscopy

The study of blood vessels and microcirculation created interest among surgeons who were keen to understand vascularity. In 1970, surgeons began researching the arterial vascularization of the larynx through the examination of operated specimens. This led to a better understanding of the development and progression of laryngeal tumors. Surgeons who work with these specimens can determine the location of the tumor, its extent, and the amount of infiltration. Other specialties have also borrowed endoscopes from urology to analyze specimens.

Endoscopes provide a superior view compared to that of an operating microscope. In 1995, Karl Storz developed a set of endoscopes exclusively for intra-operative assessment of the larynx. This technique was called contact endoscopy, where they were allowed to examine the superficial epithelium of the larynx. During the procedure, the endoscope was brought into contact with the tissue. By pressing a button near the optical end, the magnification could be increased to get a better view of the surface epithelium and the tissue microstructure. This allowed for a better understanding of what was happening at the tissue level.

Rigid endoscopes associated with micro laryngoscopy allowed direct observation of the vascular networks and alterations in the vascular networks, and the first description of contact endoscopy was given by Desormeaux in 1865; he tried to understand the vascular network of the bladder mucosa.

He put the endoscope in contact with the bladder mucosa and tried to understand the vasculature pattern, using amplification of 60 X and 150 X, which allows for the in vivo and situ observation of the mucosal blood vessels. This will help you understand the tissue microcirculation of the tissue vasculature, visualize the superficial layer of the mucosa, and understand any breach in the layers and continuity. We can't see deep.

By staining the superficial layers by applying methylene blue for a maximum of 4 to 5 minutes before contact endoscopy, it is possible to visualize the cells of the superficial layer of the mucosa of the larynx. This allows diagnosis, the evaluation of the extension of the lesions, and an understanding of the tissue structures, the safe margin, and negative margins along with a side of the tumor.

Contact endoscopy helps determine the safety margin for this tumor with an Olympus system of imaging, which is called narrowband imaging. Until 2007, contact endoscopy and illumination from Olympus was combined to enhance the observation of mucosal vascular networks. Hemoglobin in the blood vessels selectively captures a specific wavelength of light. The light emitted is then absorbed by hemoglobin, providing better contrast of the vascular system and allowing for visualization of deeper tissues.

Contact endoscopy is a clinical evaluation of anatomical pathological concepts of mucosal illness in multiple sites and stages, often associated with etiology and pathological factors.

This technique allows observation of vascular and cellular alteration of the mucosa in both outpatient clinics and operating theatres. Non-invasive pathological evaluation can be made by contact endoscopy. However, it is important to note that they are not a replacement for biopsy, histopathology, or cytology.

These are an add-on tool to better understand superficial tissues in a non-invasive way. This allows, in many cases, for the diagnosis to be made at the time of observation, having a direct implication on the planning and method of treatment that is chosen. Contact endoscopy may deliver further information on the subclinical staging and improve understanding of the physiopathology of the diagnosed condition.

The objective of contact endoscopy is not to visualize at the surface what is expected to be observed from histological sections and it should not be considered a substitute for biopsy.

Instead, it is a clinical method that adds to the information available during an endoscopic examination.

These techniques add to the available technology for better diagnoses in outpatient rooms. They support cytology as an anatomical and pathological examination, not as a replacement.

Technique

The Karl Storz (8715AA) contact micro laryngoscope is an endoscope that has a diameter of 5.8 mm and a length of 24 cm. Another contact endoscope with an angulation of 30 degrees was used to access certain areas of the larynx that are not directly accessible.

Later, a smaller laryngoscope of eighteen centimeters was developed to observe the nasal cavity, oral cavity, oropharynx, and nasopharynx. The use of contact endoscopy has expanded, particularly in the buckle mucosa, to diagnose a patch to determine whether it is an invasive cancer. Although we cannot receive a definite answer, we can obtain a preoperative adjuvant diagnosis with contact endoscopy.

Contact endoscopy is performed under general anesthesia with endotracheal intubation at the level of the larynx and hypopharynx. Some people question the necessity of performing contact endoscopy under general anesthesia if the patient is already intubated. They argue that it's better to remove a tissue and send it for proper pathological evaluation. 

However, contact endoscopy is essential when removing a lesion for excision, as it helps to understand the proper margins of the tissue and whether it is benign or malignant. Even if the lesion is behind, it's still important to take a negative margin that can be identified with contact endoscopy, as it will help to preserve the superficial lamina propria. 

This approach is particularly useful for patients who have been intubated and are under anesthesia. Observation of the nasal mucosa, nasopharynx, mouth, and oropharynx is often possible without anesthesia.

For visualizing the vessels, contact endoscopy can be applied directly to the mucosa without staining. The microcirculation is visible with illumination from a regular endoscopy source. However, with Olympus narrowband imaging, the emitted light is absorbed by the hemoglobin of the erythrocytes, which improves the visibility of the vascular network and allows the identification of deeper tissues.

Methylene blue is used to stain the mucosa to observe the cells of the epithelium. The contrast is compared to that of the surrounding neighboring tissues, improving understanding of the vascular architecture. To understand the epithelial structure, methylene blue is recommended.

The contact endoscope has a round control near the proximal ocular end, where the camera can be applied or directly viewed, and the magnification can be increased or decreased by 60X to 150X.

By sliding the contact endoscope over the mucosa, it is possible to visualize cells and their alteration at the level of the lesions and neighboring mucosa.

Furthermore, it allows mapping of the disease or various diseases that can occur at distinct sites and distinct stages. Video recording of the procedure can be beneficial in identifying any missed observations. The recording can be reviewed and analyzed by an otolaryngologist, pathologist, or psychologist. Finally, the image must be shared and reviewed to allow for proper visualization and analysis.

Hope you found this blog helpful for your Basic Sciences Preparation. For more informative and interesting posts like these, keep reading PrepLadder’s blogs. 

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