Читать книгу Gastrointestinal Pathology - Группа авторов - Страница 11

Modern endoscopic equipment can be divided in two general categories: the endoscope that allows access to the gastrointestinal tract and accessory devices that are typically passed through the working channel of the endoscope to directly acquire tissue, including biopsy forceps, snares, fine‐needle aspiration devices, and cytology brushes. Recent developments in tissue sampling include devices that are capable of wide‐field, often definitive, endoscopic resection of early neoplasia and invasive carcinoma.

A modern endoscope is a remarkably robust and versatile instrument including a light source, optical lenses with a video capture device, image processing, and display equipment, and importantly for the purposes of tissue acquisition, an accessory channel ranging from 1 to 6 mm (typically 3–4 mm), which allows passage of devices for mechanical collection of tissue (Figures 1.1 and 1.2).

There is a general trade‐off between the diameter of the instrument and the ease and comfort with which it can be passed through the natural orifices of the body such as the mouth and anus. In general the larger the outer diameter, the larger the accessory channel is to accommodate larger instruments for tissue acquisition. A fundamental limitation of most flexible endoscopes, as opposed to surgical instruments, is that all accessories pass through a single access point of the endoscope. As compared to surgical instruments with multiple access points, the endoscopic devices do not typically allow triangulation to acquire a large bulk tissue or resect entire organs. For this reason, most tissue is sampled through pinch forceps, needle aspiration, or wire loop snare devices. More recently, electrosurgical needles and other cutting tools have been developed, which have allowed wide‐field resection of tissues of virtually any diameter (Figure 1.3).

Figure 1.1 Endoscope with control handle and tip. The tip contains a light source, imaging window, and accessory channel through which various tissue acquisition devices can be passed.

Figure 1.2 Endoscopic processor, which converts the light captured from the endoscope tip into a visible image for display.

Source: Olympus America, Inc. With permission.

Figure 1.3 (a) Tools for performing endoscopic resection including endoscopic submucosal dissection (ESD).

Source: Zeon Medical.

(b) Standard and insulated tip electrocautery knives for incision and dissection.

Source: © 2017 Korean Society of Gastrointestinal Endoscopy.

(c) CO₂ insufflator for luminal distension, which is preferred to air given rapid reabsorption.

Source: Olympus.

(d) Distal attachment hood to facilitate maintaining view within the submucosal space.

Source: Fujifilm medical.

(e) Injection fluid (hyaluronic acid; Mucoup [Johnson and Johnson]) for submucosal lifting.

Source: Gut and Liver.