Gastrointestinal Pathology. Группа авторов

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.

Pinch Biopsy Forceps

The flexible pinch biopsy forceps have been one of the most versatile of all instruments for tissue acquisition. These typically involve a flexible steel cable and lever device with two sharp‐edged cups, which can be opened and closed to acquire tissue (Figure 1.4).

Standard endoscopic sampling typically acquires tissue from the mucosa and occasionally a submucosal depth of the intestinal wall; however, large‐capacity forceps as well as multiple sampling including “bite on bite” allow sampling of the deeper layers. Pinch biopsy forceps come in multiple sizes from very small instruments such as a pediatric forceps, which can be passed through very small working channels. Recent development of very tiny forceps makes it possible to pass them through special endoscopes into the bile or pancreas duct and to pinch biopsy outside of the traditional gastrointestinal lumen (Figure 1.5).

      Studies comparing jumbo forceps to standard forceps have generally not shown significant advantages of larger capacity forceps. A limitation of most forceps is the inability to sample tissue in the submucosa routinely. This is highlighted in studies looking for Barrett's esophagus after the surface epithelium has been ablated. Biopsy forceps can remove tissue with mechanical closure alone or with electrocautery (“hot biopsy”) although the use of hot biopsy has diminished significantly due to increased risks of complication and tissue damage in the biopsy specimen.

Figure 1.4 Endoscopic biopsy forceps in the open position. The needle‐like pin in the center holds the tissue in place so one to two samples can be obtained per pass.

Figure 1.5 Micro biopsy forceps <1 mm in diameter, which can be passed through specialized endoscopes into the bile duct, pancreas duct, or via 19‐gauge needles for extraluminal tissue sampling.

      Source: Boston Scientific Corporation with permission.

Figure 1.6 Endoscopic snare for polypectomy. The wire loop is extended in the open position outside the plastic sheath. When closed, the wire loop is strangulated and resects the polyp tissue.

Figure 1.7 Endoscopic cytology brush. Note the abrasive brush extended beyond the protective plastic sheath.

Endoscopic Snare Devices

Endoscopic snare devices have also been widely used for resection of polypoid as well as flat lesions throughout the gastrointestinal tract. They have been remarkably versatile and effective over the past four decades. Endoscopic snares typically involve a metallic wire, which may braided or monofilament (Figure 1.6).

      A wire loop is generally constrained within a small caliber plastic catheter. At the distal end of the catheter, the wire loop can be opened to various sizes to grasp and resect polyps of different sizes. Typical sizes include loops 5–30 mm in diameter. There are numerous different shapes including oval, hexagonal, and asymmetric “duck bill.” Snares also come in various degrees of stiffness, which allow resection of lesions of many shapes and sizes. Tissue can be resected with mechanical closure alone (so‐called “cold snare”) or with mechanical plus electrosurgical cutting (“hot snare”). Recent studies suggest that cold snare is associated with lower risk of bleeding and bowel wall injury.

Endoscopic Brush Cytology

Abrasive brush cytology has been used in many different fields of tissue sampling. Typical endoscopic brush is constrained within a plastic catheter similar to endoscopic snares (Figure 1.7).

After passing through the accessory channel of the endoscope, the abrasive brush is exposed and rubbed against the area of tissue sampling. This is most commonly applied to obtain specimens