Patent Publication Number: US-2020281619-A1

Title: Insertable endoscopic instrument for tissue removal with retractable tool at cutting tip

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present disclosure claims the benefit of and priority to U.S. Provisional Application No. 62/567,664, titled “INSERTABLE ENDOSCOPIC INSTRUMENT FOR TISSUE REMOVAL WITH RETRACTABLE BLADE AT CUTTING TIP,” filed Oct. 3, 2017, the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     Colon cancer is the third leading cause of cancer in the United States but is the second leading cause of cancer-related deaths. Colon cancer arises from pre-existing colon polyps (adenomas) that occur in as many as 35% of the US population. Colon polyps can either be benign, precancerous or cancerous. Colonoscopy is widely regarded as an excellent screening tool for colon cancer that is increasing in incidence worldwide. According to the literature, a 1% increase in colonoscopy screening results in a 3% decrease in the incidence of colon cancer. The current demand for colonoscopy exceeds the ability of the medical system to provide adequate screening. Despite the increase in colon cancer screening the past few decades, only 55% of the eligible population is screened, falling far short of the recommended 80%, leaving millions of patients at risk. 
     Due to the lack of adequate resources, operators performing a colonoscopy typically only sample the largest polyps, exposing the patient to sample bias by typically leaving behind smaller less detectable polyps that could advance to colon cancer prior to future colonoscopy. Because of the sample bias, a negative result from the sampled polyps does not ensure the patient is truly cancer-free. Existing polyps removal techniques lack precision are cumbersome and time consuming. 
     At present, colon polyps are removed using a snare that is introduced into the patient&#39;s body via a working channel defined within an endoscope. The tip of the snare is passed around the stalk of the polyp to cut the polyp from the colon wall. Once the cut has been made, the cut polyp lies on the intestinal wall of the patient until it is retrieved by the operator as a sample. To retrieve the sample, the snare is first removed from the endoscope and a biopsy forceps or suction is fed through the same channel of the endoscope to retrieve the sample. 
     Accordingly, there is a need for an improved endoscopic instrument that increases the precision and speed of polyp removal for biopsy. 
     SUMMARY 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended that this Summary be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that offer any or all advantages or solve any or all state of the art problems. 
     An improved endoscopic instrument is provided that can precisely remove sessile polyps and efficiently obtain samples of multiple polyps from a patient. In particular, the improved endoscopic instrument is capable of debriding one or more polyps and retrieving the debrided polyps without having to alternate between using a separate retractable tool and a separate sample retrieving tool. The sampling can be integrated with colonoscopy inspection. In some implementations, the endoscopic instrument can cut and remove tissue from within a patient. In some such implementations, the endoscopic instrument can cut and remove tissue substantially simultaneously from within a patient accessed through a flexible endoscope. 
     In one aspect, an endoscopic instrument includes an outer cannula and an inner cannula disposed within the outer cannula, a tool channel, a retractable tool, and a retractable tool actuator. The tool channel is defined within a radial wall of the outer cannula or positioned adjacent to the radial wall of the outer cannula. The retractable tool includes a distal tip and sized to fit within the tool channel. The retractable tool actuator is configured to move, responsive to actuation of the retractable tool actuator, the retractable tool along the tool channel from a first position in which the distal tip of the retractable tool is within the tool channel to a second position in which the distal tip of the retractable tool extends beyond a distal end of the outer cannula. 
     In another aspect, a method of operating an endoscopic instrument includes positioning the endoscopic instrument in proximity to a site of a subject, the endoscopic instrument including an outer cannula and inner cannula disposed within the outer cannula, a tool channel defined within a radial wall of the outer cannula or positioned adjacent to the radial wall of the outer cannula; receiving a control signal at a retractable tool actuator of the endoscopic instrument; moving, by the retractable tool actuator responsive to the control signal, a retractable tool along the tool channel from a first position in which a distal tip of the retractable tool is within the tool channel to a second position in which a distal tip of the retractable tool extends beyond a distal end of the outer cannula; and retrieving a sample of the subject from the site of the subject. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure is illustratively shown and described in reference to the accompanying drawing in which: 
         FIG. 1A  illustrates various types of polyps that can form within a body. 
         FIG. 1B  is an exploded perspective view of an improved endoscopic instrument according to embodiments of the present disclosure. 
         FIG. 1C  is an end view of the improved endoscopic instrument shown in  FIG. 1A  according to embodiments of the present disclosure. 
         FIG. 1D  is a cross-sectional view of the improved endoscopic instrument shown in  FIG. 1B  taken along the section A-A according to embodiments of the present disclosure. 
         FIG. 2  is a block diagram of an endoscopic instrument including a retractable tool according to embodiments of the present disclosure. 
         FIG. 3A  is a sectional view of a distal end of an endoscopic instrument including a retractable tool operated by a linear actuator in a first configuration according to embodiments of the present disclosure. 
         FIG. 3B  is a sectional view of the endoscopic instrument of  FIG. 3A  in a second configuration according to embodiments of the present disclosure. 
         FIG. 3C  is a sectional view of a distal end of an endoscopic instrument including a retractable tool operated by a control wire in a first configuration according to embodiments of the present disclosure. 
         FIG. 3D  is a sectional view of a distal end of an endoscopic instrument including a retractable tool operated by electromagnets in a first configuration according to embodiments of the present disclosure. 
         FIG. 3E  is a detail view of the endoscopic instrument of  FIG. 3D  in the first configuration according to embodiments of the present disclosure. 
         FIG. 3F  is a detail view of the endoscopic instrument of  FIG. 3D  in a second configuration according to embodiments of the present disclosure. 
         FIG. 4  is a flow diagram of a method of operating an endoscopic instrument including a retractable tool according to embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Technologies provided herein are directed towards an improved flexible endoscopic instrument that can precisely and efficiently obtain samples of single and multiple polyps and neoplasms from a patient. In particular, the improved endoscopic instrument is capable of debriding samples from one or more polyps and retrieving the debrided samples without having to remove the endoscopic instrument from the treatment site within the patient&#39;s body. 
       FIG. 1A  illustrates various types of polyps that can form within a body. Most polyps may be removed by snare polypectomy, though especially large polyps and/or sessile or flat polyps must be removed piecemeal with biopsy forceps or en bloc using endoscopic mucosal resection (EMR). A recent study has concluded that depressed sessile polyps had the highest rate for harboring a malignancy at 33%. The same study has also found that non-polypoid neoplastic lesions (sessile polyps) accounted for 22% of the patients with polyps or 10% of all patients undergoing colonoscopy. There are multiple roadblocks to resecting colon polyps, namely the difficulties in removing sessile polyps, the time involved in removing multiple polyps and the lack of reimbursement differential for resecting more than one polyp. Since resecting less accessible sessile polyps presents challenges and multiple polyps take more time per patient, most polyps are removed piece meal with tissue left behind as polyps increase in size, contributing to a sampling bias where the pathology of remaining tissue is unknown, leading to an increase in the false negative rate. 
     Colonoscopy is not a perfect screening tool. With current colonoscopy practices the endoscopist exposes the patient to sample bias through removal of the largest polyps (stalked polyps), leaving behind less detectable and accessible sessile/flat polyps. Sessile polyps are extremely difficult or impossible to remove endoscopically with current techniques and often are left alone. An estimated 28% of stalked polyps and 60% of sessile (flat) polyps are not detected, biopsied or removed under current practice, which contributes to sample bias and a 6% false-negative rate for colonoscopy screening. Current colonoscopy instruments for polyp resection are limited by their inability to adequately remove sessile polyps and inefficiency to completely remove multiple polyps. According to the clinical literature, sessile polyps greater than 10 mm have a greater risk of malignancy. Sessile polyp fragments that are left behind after incomplete resection will grow into new polyps and carry risks for malignancy. 
     In the recent past, endoscopic mucosal resection (EMR) has been adopted to remove sessile polyps. EMR involves the use of an injection to elevate surrounding mucosa followed by opening of a snare to cut the polyp and lastly use of biopsy forceps or a retrieval device to remove the polyp. The introduction and removal of the injection needle and snare through the length of the colonoscope, which is approximately 5.2 feet, must be repeated for the forceps. 
     The present disclosure relates to an endoscopic instrument that is capable of delivering an innovative alternative to existing polyp removal tools, including snares, hot biopsy and EMR, by introducing a flexible powered instrument that that works with the current generation colonoscopes and can cut and remove any polyp. The endoscopic instrument described herein can be designed to enable physicians to better address sessile or large polyps as well as remove multiple polyps in significantly less time. Through the adoption of the endoscopic instrument described herein, physicians can become more efficient at early diagnosis of colorectal cancer. 
     The present disclosure will be more completely understood through the following description, which should be read in conjunction with the drawings. In this description, like numbers refer to similar elements within various embodiments of the present disclosure. Within this description, the claims will be explained with respect to embodiments. The skilled artisan will readily appreciate that the methods, apparatus and systems described herein are merely exemplary and that variations can be made without departing from the spirit and scope of the disclosure. 
     A. Endoscopic Instrument 
     Referring back to the drawings,  FIGS. 1B-1D  illustrate an endoscopic instrument  100  according to embodiments of the present disclosure. The endoscopic instrument  100  may be similar to various endoscopic instrument described in U.S. patent application Ser. No. 15/459,870, which is incorporated herein by reference in its entirety. 
     The endoscopic instrument  100  can be configured to obtain samples of polyps and neoplasms from a patient. The endoscopic instrument  100  can be configured to be rotated by a torque source (e.g., a motor coupled to a drive assembly or drive shaft of the endoscopic instrument  100 ). The endoscopic instrument  100  can be configured to flow irrigation fluid out into a site within a subject (e.g., a site within a colon, esophagus, lung of the subject). The endoscopic instrument  100  can be configured to resect material at a site within a subject. The endoscopic instrument  100  can be configured to provide a suction force via an aspiration channel to obtain a sample of the material resected at a site within a subject. In some implementations, the endoscopic instrument  100  can be configured to be inserted within an instrument channel, such as an instrument channel of an endoscope (e.g., a gastroscope, such as a colonoscope, a laryngoscope, or any other flexible endoscope). 
     The endoscopic instrument  100  includes a proximal connector  110  and a flexible torque delivery assembly  200 . The proximal connector  110  is configured to couple a drive assembly  150  (e.g., a drive assembly including a drive shaft configured to be rotated by a source of rotational energy) of the endoscopic instrument  100  to the flexible torque delivery assembly of the endoscopic instrument  100 . In some implementations, the proximal connector  110  includes a first connector end  114  at which the drive assembly  150  is coupled, and a second connector end  118  at which the flexible torque delivery assembly  200  is coupled. As shown in  FIGS. 1B and 1D , the first connector end  114  includes an inner wall  116  defining an opening in which the drive assembly  150  can be received. For example, in some implementations, the proximal connector  110  can be used to connect the drive assembly  150  to a drive shaft of a surgical console. The proximal connector  110  includes a drive transfer assembly  122 . The drive transfer assembly  122  is configured to be operatively coupled to the drive assembly  150 , receive torque from the drive assembly  150  when the drive assembly  150  rotates, and transfer the torque to the flexible torque delivery assembly  200  in order to rotate the flexible torque delivery assembly  200 . In some implementations, the drive assembly  150 , drive transfer assembly  122 , and at least a portion of the flexible torque delivery assembly  200  are coaxial. For example, the drive transfer assembly  122  can be engaged to the drive assembly  150  along a drive axis  102 , and the drive transfer assembly  122  can also be engaged to the flexible torque delivery assembly  200  at a proximal end  204  of the flexible torque delivery assembly  200  along the drive axis  102 . It should be appreciated that rotating the flexible torque delivery assembly may include causing the flexible torque delivery assembly to rotate a component (such as an inner cannula) at one of the flexible torque delivery assembly. 
     In some implementations, the drive transfer assembly  122  includes gears, belts, or other drive components to control the direction and/or torque transferred from the drive assembly  150  to the flexible torque delivery assembly  200 . For example, such drive components can be positioned at an angle to one another to change an axis of rotation of the flexible torque delivery assembly  200 , or offset from one another to shift an axis of rotation of the flexible torque delivery assembly  200  relative to the drive axis  102 . 
     In some implementations, the drive assembly  150  includes a drive engagement member  152 . The drive engagement member  152  is configured to engage the drive assembly  150  to a source of rotational energy (e.g., a drive rotated by a motor, such as console drive assembly of a surgical console). The drive engagement member  152  can be configured to be fixedly and/or rigidly connected to the console drive assembly, such that the drive engagement member  152  rotates in unison with the console drive assembly. For example, as shown in  FIG. 1B , the drive engagement member  152  includes a proximal drive end  154  including a fitting (e.g., hex fitting, pin fitting, etc.) configured to engage (e.g., lock with, mate with, fixedly engage, frictionally engage, etc.) a console drive assembly. As such, rotation of the console drive assembly causes rotation of the drive engagement member  152 . 
     In some implementations, the drive assembly  150  includes one or more shaft components  154  configured to transfer rotation of the drive engagement member  150  to the drive transfer assembly  122 . In some implementations, the drive transfer assembly  122  includes the one or more shaft components  156 . The shaft components  156  can include an insulator member  156   a  (e.g., a heat sheath, heat shrink, etc.) configured to insulate components of the drive assembly  150  from heat generated by rotation of the drive assembly or components thereof. The shaft components  156  can include a cutter  156   b.  The shaft components  156  can include a shaft torque coil  156   c  which may be similar to other torque coils described herein. In some implementations, the shaft components  156  can include a shaft torque rope. The shaft components  156  can include a shaft tube  156   d.  The shaft tube  156   d  can include a radius that is less than a relatively greater radius of the drive engagement member  152  (e.g., a relatively greater radius that may facilitate receiving rotational energy from a drive shaft or other rotational energy source, such as by engaging the drive engagement member  152  to a console drive assembly). For example, the shaft tube  156   d  can include a relatively lesser smaller corresponding more closely to a radius of the drive transfer assembly  122  and/or the flexible torque delivery assembly  200 . In such implementations, the torque received at the drive transfer assembly  122  and/or the flexible torque delivery assembly  200  can be modified (e.g., increased) in a manner corresponding to the change in radius between the radius of the drive engagement member  152  and the radius of the shaft tube  156   d.    
     In some implementations, the cutting assembly  201  can include an outer cannula and an inner cannula disposed within the outer cannula. The outer cannula can define an opening  208  through which material to be resected can enter the cutting assembly  201 . In some implementations, the opening  208  is defined through a portion of the radial wall of the outer cannula. In some implementations, the opening  208  may extend around only a portion of the radius of the outer cannula, for example, up to one third of the circumference of the radial wall. As the aspiration channel extends between a vacuum port (e.g., vacuum port  126 ) and the opening  208 , any suction applied at the vacuum port causes a suction force to be exerted at the opening  208 . The suction force causes material to be introduced into the opening or cutting window of the outer cannula, which can then be cut by the inner cannula of the cutting assembly  201 . 
     The inner cannula can include a cutting section that is configured to be positioned adjacent to the opening  208  such that material to be resected that enters the cutting assembly  201  via the opening  208  can be resected by the cutting section of the inner cannula. The inner cannula may be hollow and an inner wall of the inner cannula may define a portion of an aspiration channel that may extend through the length of the endoscopic instrument. A distal end of the inner cannula can include the cutting section while a proximal end of the inner cannula can be open such that material entering the distal end of the inner cannula via the cutting section can pass through the proximal end of the inner cannula. In some implementations, the distal end of the inner cannula can come into contact with an inner surface of a distal end of the outer cannula. In some implementations, this can allow the inner cannula to rotate relative to the outer cannula along a generally longitudinal axis, providing more stability to the inner cannula while the inner cannula is rotating. In some implementations, the size of the opening can dictate the size of the materials being cut or resected by the inner cannula. As such, the size of the opening may be determined based in part on the size of the aspiration channel defined by the inner circumference of the flexible torque coil. 
     The endoscopic instrument  100  can include a flexible torque coil  212  that is configured to couple to the proximal end of the inner cannula at a distal end of the flexible torque coil  212 . The flexible torque coil can include a fine coil with multiple threads and multiple layers, which can transmit the rotation of one end of the flexible torque coil to an opposite end of the flexible torque coil. Each of the layers of thread of the flexible torque coil can be wound in a direction opposite to a direction in which each of the layers of thread adjacent to the layer of thread is wound. In some implementations, the flexible torque coil can include a first layer of thread wound in a clockwise direction, a second layer of thread wound in a counter-clockwise direction and a third layer of thread wound in a clockwise direction. In some implementations, the first layer of thread is separated from the third layer of thread by the second layer of thread. In some implementations, each of the layers of thread can include one or more threads. In some implementations, the layers of thread can be made from different materials or have different characteristics, such as thickness, length, among others. 
     The flexibility of the torque coil  212  allows the coil to maintain performance even in sections of the torque coil  212  that are bent. Examples of the flexible torque coil  212  include torque coils made by ASAHI INTECC USA, INC located in Santa Ana, Calif., USA. In some implementations, the flexible torque coil  212  can be surrounded by a sheath or lining (e.g., sheath  214 ) to avoid frictional contact between the outer surface of the flexible torque coil  212  and other surfaces. In some implementations, the flexible torque coil  212  can be coated with Polytetrafluoroethylene (PFTE) to reduce frictional contact between the outer surface of the flexible torque coil  212  and other surfaces. The flexible torque coil  212  can be sized, shaped or configured to have an outer diameter that is smaller than the diameter of the instrument channel of the endoscope in which the endoscopic instrument is to be inserted. For example, in some implementations, the outer diameter of the flexible torque coil can be within the range of 1-4 millimeters. The length of the flexible torque coil can be sized to exceed the length of the endoscope. In some implementations, the inner wall of the flexible torque coil  212  can be configured to define another portion of the aspiration channel that is fluidly coupled to the portion of the aspiration channel defined by the inner wall of the inner cannula of the cutting assembly  201 . A proximal end of the flexible torque coil  212  can be coupled to the proximal connector  110  (e.g., to the drive transfer assembly  122  of the proximal connector  110 , etc.). 
     The endoscopic instrument  100  can include a flexible outer tubing  206  that can be coupled to the proximal end of the outer cannula. In some implementations, a distal end of the flexible outer tubing  206  can be coupled to the proximal end of the outer cannula using a coupling component. In some implementations, the outer cannula can be configured to rotate responsive to rotating the flexible outer tubing. In some implementations, the flexible outer tubing  206  can be a hollow, braided tubing that has an outer diameter that is smaller than the instrument channel of the endoscope in which the endoscopic instrument  100  is to be inserted. In some implementations, the length of the flexible outer tubing  206  can be sized to exceed the length of the endoscope. The flexible outer tubing  206  can define a bore through which a portion of the flexible outer tubing  206  extends. The flexible outer tubing  206  can include braids, threads, or other features that facilitate the rotation of the flexible outer tubing  206  relative to the flexible torque coil, which is partially disposed within the flexible outer tubing  206 . The flexible outer tubing can define a portion of an irrigation channel for outputting fluid to a site within a subject. 
     The endoscopic instrument  100  can include a rotational coupler  216  configured to be coupled to a proximal end of the flexible outer tubing  206 . The rotational coupler  216  may be configured to allow an operator of the endoscopic instrument to rotate the flexible outer tubing  206  via a rotational tab  218  coupled to or being an integral part of the rotational coupler  216 . By rotating the rotational tab  218 , the operator can rotate the flexible outer tubing and the outer cannula along a longitudinal axis of the endoscope and relative to the endoscope and the inner cannula of the cutting assembly  201 . In some implementations, the operator may want to rotate the outer cannula while the endoscopic instrument is inserted within the endoscope while the endoscope is within the patient. The operator may desire to rotate the outer cannula to position the opening of the outer cannula to a position where the portion of the radial wall of the outer cannula within which the opening is defined may aligned with the camera of the endoscope such that the operator can view the material entering the endoscopic instrument for resection via the opening. This is possible in part because the opening is defined along a radial wall extending on a side of the outer cannula as opposed to an opening formed on the axial wall of the outer cannula. 
     In some implementations, a proximal end  220  of the rotational coupler  216  can be fluidly coupled to the proximal connector  110 , such that the irrigation channel of the endoscopic instrument  100  passes from an irrigation port  134  through the flexible outer tubing  206  into the rotational coupler  216 . Irrigation fluid entering the proximal connector  110  at the irrigation port  134  can thus pass through the rotational coupler  216  in order to be outputted at a site within a subject. In some implementations, the rotational coupler  216  can be a rotating luer component that allows a distal end  222  of the rotational coupler  216  to rotate relative to the proximal end  220  of the rotational coupler  216 . In this way, when the flexible outer tubing  206  is rotated, the component to which the proximal end of the rotational coupler  216  is coupled, is not caused to rotate. The rotational coupler  216  can define a bore along a central portion of the rotational coupler  216  through which a portion of the flexible torque coil  212  extends. In some implementations, the rotational coupler  216  can be a male to male rotating luer connector. In some implementations, the rotational coupler can be configured to handle pressures up to 1200 psi. 
     In some implementations, the flexible torque delivery assembly  200  is configured to be fluidly coupled to a vacuum source to apply a suction force to the aspiration channel. The aspiration channel allows for fluid and material (e.g., a sample to be obtained) to be drawn into the distal end  204  of the flexible torque delivery assembly  200  in order to flow to the proximal end  202  of the flexible torque delivery assembly  200 . For example, after the cutting assembly  201  has been used to resect material from a site within a subject, vacuum pressure can be applied through the aspiration channel to draw (e.g., transfer by suction, etc.) fluid and material into the flexible torque delivery assembly  200 . 
     In some implementations, the proximal connector  110  is configured to be coupled to a vacuum source to provide a suction force for aspiration. For example, as shown in  FIGS. 1B and 1D , the proximal connector  110  includes a vacuum port  126  (e.g., aspiration port). The vacuum port/aspiration port  126  can be similar to other aspiration ports disclosed herein. The vacuum port  126  is configured to fluidly couple an aspiration channel of the endoscopic instrument  100  to a vacuum source (e.g., to a vacuum source with a specimen receiver positioned between the vacuum source and the endoscopic instrument). The vacuum port  126  is configured to transmit a suction force applied to the vacuum port  126  to the aspiration channel, in order to draw fluid and material entering the distal end  204  of the endoscopic instrument  100  through the aspiration channel towards the vacuum source. In some implementations, such as shown in  FIGS. 1B and 1D , the vacuum port  126  includes a vacuum port channel  130  oriented transverse to the drive axis  102  (and thus the aspiration channel). This may facilitate coupling tubing to the vacuum port  126  that extends to a specimen receiver or vacuum source without interfering with manipulation of the proximal connector  110  and the endoscopic instrument  100 . In various implementations, the vacuum port channel  130  can be oriented at varying angles relative to the drive axis  102 . In some implementations, vacuum tubing  132  can be coupled to the vacuum port  126 . 
     In some implementations, the proximal connector  110  is configured to be coupled to a fluid source to provide fluid to be outputted by the endoscopic instrument  100  to a site within a subject. As shown in  FIGS. 1B-1D , the proximal connector  110  includes an irrigation port  134 , including an irrigation port channel  136 , configured to receive fluid from a fluid source. The irrigation port  134  is configured to be fluidly coupled to an irrigation channel of the flexible torque delivery assembly  200  (e.g., an irrigation channel defined between the flexible outer tubing  206  and the flexible torque coil  212  and extending to an opening at the distal end  204  of the flexible torque delivery assembly  200 ), such that fluid can flow from the proximal connector  110  through flexible torque delivery assembly  200  to be outputted at a site within a subject. In some implementations, the fluid (e.g., irrigation fluid) can be used to cool the flexible torque delivery assembly  200 , which may generate heat due to friction caused by rotation or other movements. In some implementations, the fluid can be used to wash a site within a subject. In some implementations, the fluid provides lubrication to facilitate rotation or other movement of components of the endoscopic instrument  100  relative to one another. In some implementations, the irrigation port  134  is configured to be coupled to a fluid transfer device or irrigation pump. The irrigation port  134  receives a flow of irrigation fluid from the irrigation pump and transfers the fluid into the irrigation channel. In some implementations, the irrigation channel is defined to include the irrigation port  134  and/or tubing connecting the irrigation port  134  to the fluid source. In some implementations, the irrigation port  134  can be coupled to a fluid source by fluid tubing  140 . The fluid tubing  140  can be coupled to a fitting  144  (e.g., vented spike fitting, non-vented spike fitting, etc.) configured to interface the fluid tubing  140  to a fluid source. 
     B. Systems and Methods for Insertable Endoscopic Instrument for Tissue Removal with Retractable Tool at Cutting Tip 
     In existing endoscopic instrument systems, a cutting assembly may be provided which can be rotated to resect polyps and other materials from a site within a subject. However, in certain use cases or procedures, the cutting assembly may not be able to effectively resect desired material, such as to resect relatively large portions of polyps adjacent to where the polyps protrude from underlying tissue. 
       FIG. 2  illustrates a block diagram of an endoscopic instrument  250  including a retractable blade according to embodiments of the present disclosure. The endoscopic instrument  250  may incorporate features of the endoscopic instrument  100  described with reference to  FIGS. 1B-1D . In some implementations, the endoscopic instrument  250  includes a drive assembly  255 , a proximal connector  260 , a cutting assembly  265 , and a flexible torque delivery assembly  270 . The drive assembly  255  can be coupled to the flexible torque delivery assembly  270  via the proximal connector  260  to cause the flexible torque delivery assembly  270  to rotate. 
     In some implementations, the endoscopic instrument  200  includes a retractable tool  275  and a retractable tool actuator  280 . The retractable tool  275  is configured to resect material at a site within a subject. The retractable tool  275  can be configured to move in a direction transverse to a direction in which the cutting assembly  265  rotates, which may enable greater the endoscopic instrument  250  to be used for a greater range of procedures and tissue manipulation while maintaining a compact form factor useful for endoscopic procedures. 
     The retractable tool  275  may be disposed at a distal end of the endoscopic instrument  250  in a manner similar to an instrument channel, camera, or camera lens of various endoscopic instruments described herein. In some embodiments, the retractable tool  275  is disposed closer to an outer surface of the endoscopic instrument  250  than a longitudinal axis of the endoscopic instrument  250 . As such, rotation of the endoscopic instrument  250  about the longitudinal axis of the endoscopic instrument  250  may allow the retractable tool  275  to reach various locations around the site within the subject which would otherwise be inaccessible to cutting assembly  265  (e.g., if the cutting assembly  265  is located along the longitudinal axis). 
     The retractable tool  275  can be configured to cut, resect, excise, or otherwise remove a sample of material (e.g., tissue) at the site in the subject. The retractable tool  275  may include a relatively thin edge extending in a direction generally parallel to the longitudinal axis of the endoscopic instrument  250 . In some embodiments, the edge of the retractable tool  275  is serrated. The retractable tool  275  may be made from a material such as stainless steel or titanium. The retractable tool  275  may be made from a biocompatible material. The retractable tool  275  may have a rigidity greater than a threshold rigidity sufficient to resect the sample of material, given a surface area to volume ratio of the retractable tool  275 . In some implementations, the retractable tool  275  includes one or more blades. 
     The retractable tool  275  can be configured to be manipulated (e.g., moved relative to the endoscopic instrument  250 , such as by being moved out of or into the endoscopic instrument  250 ) by the retractable tool actuator  280 . In some implementations, the retractable tool actuator  280  includes a linear actuator. The retractable tool actuator  280  can be configured to drive the retractable tool  275  from a first position (e.g., a retracted position) to a second position (e.g., an extended position) and back to the first position. At the first position, a distal end of the retractable tool  275  may be disposed within the endoscopic instrument  250 . At the second position, the distal end of the retractable tool  275  may extend out of the endoscopic instrument  250 . 
     The benefit of having a retractable retractable tool  275  is to reduce the risk of injury to the subject while the retractable tool is not in use or operation. As a surgeon manipulates the endoscopic instrument  250  within the subject, the retractable tool  275  can be maintained in the retracted position such that the retractable tool  275  is not able to contact any organs, such as the colon, esophagus or other part of the subject while the endoscopic instrument is inserted within an endoscope that is inserted within the subject. At a time when the surgeon desires to use the retractable tool  275 , the surgeon may deploy the retractable tool from the retracted position to the extended position for use. After the surgeon no longer needs the retractable tool  275 , the surgeon may retract the retractable tool  275  from the deployed position to the retracted position. Both the deployment and retraction of the retractable tool  275  from the endoscopic instrument  250  can be done without having to remove the endoscopic instrument from within the subject or the endoscope within which it is inserted. 
     It should be appreciated that the retractable tool  275  and the deployment and retraction mechanisms described herein can be implemented in any medical device where there is a need to retract or stow away the retractable tool while the retractable tool is not in use. 
     In some implementations, the retractable tool actuator  280  is configured to control operation of the retractable tool  275  based on a control signal. The retractable tool actuator  280  can be configured to receive the control signal via a control line (not shown) extending within the endoscopic instrument  250  from the proximal end of the endoscopic instrument  250  to the retractable tool actuator  280 . The retractable tool actuator  280  can be configured to execute control of the retractable tool  275  based on a voltage magnitude, pulse width, or other parameter of the control signal. In some implementations, the retractable tool actuator  280  includes a processing circuit configured to receive the control signal and control operation of the retractable tool  275  based on the control signal. The retractable tool actuator  280  can be configured to control at least one of a distance the retractable tool  275  extends out of the endoscopic instrument  250  or a frequency of movement of the retractable tool  275  (e.g., based on the control signal). 
     Referring now to  FIGS. 3A-3B , an endoscopic instrument  300   a  is illustrated according to embodiments of the present disclosure. The endoscopic instrument  300   a  can incorporate features of the endoscopic instrument  200  described with reference to  FIG. 2 . In some implementations, the endoscopic instrument  300   a  includes an outer cannula  305  and an inner cutter  310  defining an inner cannula  315 . The inner cutter  310  can be configured to be rotated (e.g., by flexible torque delivery assembly  215 ) about a longitudinal axis  302  of the endoscopic instrument  300   a,  such as to resect material contacted by the inner cutter  310 . The material may be drawn into the inner cannula  315  (e.g., via a vacuum force applied through an aspiration channel). 
     The endoscopic instrument can define a tool channel  306 , which may be defined within a radial wall of the outer cannula  305  or positioned adjacent to the radial wall of the outer cannula  305 . The endoscopic instrument  300   a  includes a retractable tool  325   a  and a retractable tool actuator  330   a,  which may be disposed in the tool channel  306 . As shown in  FIG. 3A , the retractable tool  325   a  can be connected to the retractable tool actuator  330   a  by a shaft  335   a.  For example, the retractable tool actuator  330   a  can be configured to drive the shaft  335   a  along a drive axis  326  to move the retractable tool  325   a  out of (or back into) the tool channel  306 . In some implementations, the retractable tool actuator  330   a  is configured to move the retractable tool  325   a  from a first position (e.g., as shown in  FIG. 3A ) to a second position (e.g., as shown in  FIG. 3B ). For example, in the first position, a distal end  327   a  of the retractable tool  325   a  may be disposed within the tool channel  306  (e.g., the distal end  327   a  is inward of distal edge  307  of the outer cannula  305 ). In the second position, the distal end  327   a  may be disposed outside the tool channel  306 . 
     The retractable tool  325   a  includes a cutting edge  328   a.  As shown in  FIG. 3A , the cutting edge  328   a  extends from the distal end  327   a  (e.g., on a side of the retractable tool  325   a  distal to the longitudinal axis  302 ) towards the longitudinal axis  302  and the retractable tool actuator  330   a  (e.g., towards a proximal end of the endoscopic instrument  300   a ). The cutting edge  328   a  can be configured to resect material at the site within the subject, such as by being moved back and forth along a boundary of the material to be resected. The cutting edge  328   a  may include a serrated surface. 
     The retractable tool actuator  330   a  can be configured to control operation of the retractable tool  325   a  based on a control signal received via a control line  340   a.  The control line  340   a  can be configured to receive the control signal from a user interface (not shown); for example, the user interface can be configured to receive a user input and generate the control signal based on the user input. The retractable tool actuator  330   a  can be configured to determine a control parameter for controlling operation of the retractable tool  325   a,  based on the control signal. The control parameter may include one or more of a movement duration, movement frequency, or movement intermittency for movement of the retractable tool  325   a.  The retractable tool actuator  330   a  can be configured to receive electrical power via the control line  340   a  or a separate power line (not shown). The retractable tool actuator  330   a  may include a motor configured to be driven by electrical power, or a piezoelectric element configured to oscillate in response to receiving electrical power. 
     In some implementations, the retractable tool actuator  330   a  receives electrical power as an electrical signal from the control line  340   a,  where the electrical signal also carries the control signal. For example, the electrical signal received from the control line  340   a  can be modulated (e.g., modulated in voltage) in accordance with the control signal, such that an electric motor, piezoelectric element, or other drive element of the retractable tool actuator  330   a  can be activated based on power delivered by the modulated electrical signal. 
     In some implementations, the retractable tool actuator  330   a  includes a linear actuator configured to drive the retractable tool  325   a  (e.g., by shaft  335   a ) along the tool axis  326 . The linear actuator can include a motor configured to generate rotational motion, and a drive shaft connected to the motor to convert the rotational motion to reciprocal motion; the drive shaft may include or be coupled to the shaft  335   a  to cause linear motion of the retractable tool  325   a.  In some implementations, the retractable tool actuator  330   a  includes a linear encoder configured to output a signal indicating a position of the shaft, which may correspond to the position of the retractable tool  325   a.    
     The retractable tool actuator  330   a  can be configured to move the retractable tool  325   a  at the movement frequency, which may correspond to a rate at which the retractable tool  325   a  moves along the tool axis  326  (e.g., a rate at which the distal end  327   a  moves past a reference point, such as a point where the tool axis  326  intersects a plane in which the distal edge  307  lies). Similarly, the retractable tool actuator  330   a  can be configured to move the retractable tool  325   a  based on the movement duration and/or movement intermittency. In some implementations, the retractable tool actuator  330   a  is configured to deliver electricity into the retractable tool  325   a,  which may enable the retractable tool  325   a  to perform electrocautery. 
     The retractable tool actuator  330   a  may be attached to the inner cutter  315  or the outer cannula  305 . For example, the retractable tool actuator  330   a  can be configured to be rotated together with the inner cutter  315  or the outer cannula  305  while attached to the respective component. 
     Referring now to  FIG. 3C , an endoscopic instrument  300   c  is illustrated according to embodiments of the present disclosure. The endoscopic instrument  300   c  can be similar to the endoscopic instrument  300   a,  with the exception of the operation of the retractable tool actuator  330   c  as described below. The endoscopic instrument  300   c  can include a retractable tool  325   c  including a distal end  327   c  and a cutting edge  328   c,  and a retractable tool actuator  330   c.    
     In some implementations, the retractable tool actuator  330   c  includes a control wire  335   c.  The control wire can extend from a proximal end of the endoscopic instrument  300  (e.g., adjacent to a proximal connector such as the proximal connector  205  described with reference) to the retractable tool  325   c  disposed in the tool channel  306 . 
     The control wire  335   c  can include or be connected to a biasing element (e.g., a spring) disposed near the distal end of the endoscopic instrument  300   c.  The biasing element can be configured to bias the retractable tool  325   c  to the first position (e.g., the position shown in  FIG. 3C ), such that a force applied to the retractable tool  325   c  via the control wire may be greater than a bias force of the biasing element to move the retractable tool  325   c  out of the tool channel  306 . The control wire may include or be coupled to a pulley system or other mechanism configured to convert a force applied in a direction away from the distal end of the endoscopic instrument  300   c  into a force applied in a direction towards the distal end of the endoscopic instrument  300   c,  which may enable an operator of the endoscopic instrument  300   c  to apply a force to the control wire  335   c  (e.g., pull a proximal portion of the control wire  335   c  away from the distal end of the endoscopic instrument  300   c ) to cause the retractable tool  325   c  to move out of the tool channel  306 ; when the control wire  335   c  is not receiving the force, the biasing element may return the retractable tool  325   c  to the first position. The retractable tool  325   c  may be configured to move to a second position (e.g., a position similar to the second position shown in  FIG. 3B  for endoscopic instrument  300   a ) in response to receiving a force from the control wire  335   c.    
     The endoscopic instrument  300   c  can include one or more track elements  340   c.  The track element  340   c  can include a slot configured to receive the retractable tool  325   c,  which may stabilize the retractable tool  325   c  as the retractable tool  325   c  moves in or out of the tool channel  306 . 
     Referring now to  FIGS. 3D-3F , an endoscopic instrument  300   d  is illustrated according to embodiments of the present disclosure. The endoscopic instrument  300   d  can be similar to the endoscopic instruments  300   a,    300   c,  with the exception of the operation of the retractable tool  325   d  and retractable tool actuator  330   d  as described below. The endoscopic instrument  300   d  can include a retractable tool  325   d  including a distal end  327   d  and a cutting edge  328   d,  and a retractable tool actuator  330   d.    
     In some implementations, the retractable tool  325   d  includes a permanent magnet. For example, the retractable tool  325   d  may be made from a ferromagnetic material. As shown in  FIGS. 3E-3F , the retractable tool  325   d  may have a first magnetic pole (e.g., north pole) at the distal end  327   d,  and a second magnetic pole (e.g., south pole) at a proximal end  329   d  opposite the distal end. It will be appreciated that the polarity of the retractable tool  325   d  may be reversed. 
     The retractable tool actuator  330   d  can include a shaft  335   d  along which the retractable tool  325   d  can translate. For example, the retractable tool  325   d  can translate from a first position (e.g., as shown in  FIG. 3E ) to a second position (e.g., as shown in  FIG. 3F ). In some implementations, the retractable tool actuator  330   d  includes a stop  331   d  configured to limit translation of the retractable tool  325   d  in a direction towards the proximal end of the endoscopic instrument  300   d.    
     In some implementations, the endoscopic instrument  300   d  includes one or more electric power lines  340   d.  The electric power lines  340   d  are configured to carry electrical power from a proximal end of the endoscopic instrument  300   d  to the distal end shown in  FIGS. 3D-3F . Each electric power line  340   d  may include one or more electrical wires configured to deliver electrical power. The endoscopic instrument  300   d  also includes one or more electromagnets  345   d,  which can receive electricity from the electric power lines  340   d  and generate a magnetic field having a first magnetic pole and a second magnetic pole. The magnitude of the magnetic field may be controlled based on a magnitude of electric current delivered to the electromagnet  345   d  via the electric power lines  340   d.  In the configuration illustrated in  FIG. 3E , the north pole of the electromagnet  345   d  is adjacent to the distal end of the endoscopic instrument  300   d,  while the south pole of the electromagnet  345   d  is away from the distal end of the endoscopic instrument  300   d.    
     Using the magnetic field generated by the electromagnet  345   d,  the endoscopic instrument  300   d  can be configured to hold the retractable tool  325   d  in one or more stable positions. For example, at the one or more stable positions, a force balance on the retractable tool  325   d  include magnetic forces from the electromagnet  345   d  is zero. It will be appreciated that the electromagnet  345   d  and retractable tool  325   d  can be configured so that the magnetic force generated by the electromagnet  345   d  is sufficiently large compared to other forces which may be applied to the retractable tool  325   d  (e.g., gravity, pressure from fluid near the site of the subject) that such other forces may be negligible in controlling operation of the retractable tool  325   d.  As shown in  FIG. 3E , the first position may be a stable position, where south pole of the retractable tool  325   d  is closest to the distal, north poles of the electromagnets  345   d,  and the north pole of the retractable tool  325   d  is closest to the proximal, south poles of the electromagnets  345   d.    
     As shown in  FIG. 3F , the polarities of the electromagnets  345   d  have been reversed as compared to the configuration of  FIG. 3E . As such, a resultant force may be applied to the retractable tool  325   d  (e.g., due to magnetic poles of like polarity being adjacent to one another), causing the retractable tool  325   d  to be driven out of the tool channel  306  to the second position shown in  FIG. 3F . The second position may also be a stable position; in some implementations, a distal end of the shaft  335   d  may include one or more stops (not shown) configured to limit translation of the retractable tool  325   d  in a direction away from the proximal end of the endoscopic instrument  300   d.    
     In various implementations, the magnitude of the electric current delivered to different electromagnets  345   d  may be different, which may allow differing control schemes for movement of the retractable tool  325   d.  In various implementations, the endoscopic instrument  300   d  may include a plurality of electromagnets  345   d  each configured to individually receive electrical power form the electric power lines  340   d,  which can enable the electromagnets  345   d  to be turned on or off individually, such as for allowing sequential activation of the electromagnets  345   d  as the retractable tool  325   d  moves along the cutting axis  326 . 
     Referring now to  FIG. 4 , a flow diagram of a method  400  of operating an endoscopic instrument including a retractable blade is shown according to embodiments of the present disclosure. The method may be performed using various endoscopic instruments described herein (e.g., endoscopic instruments  200 ,  300   a,    300   c,    300   d ). The method may be performed using a surgical console or other user interface configured to control operation of the endoscopic instrument. The method may be performed by a surgeon, technician, or other medical professional. 
     At  405 , an endoscopic instrument is positioned in proximity to a site of a subject. The site of the subject may include a sample desired to be resected, such as a polyp within a colon of the subject, or other tissue to be resected. Positioning of the endoscopic instrument may be monitored using a camera of the endoscopic instrument. The endoscopic instrument may include an outer cannula and inner cannula disposed within the outer cannula. A tool channel may be defined within a radial wall of the outer cannula or positioned adjacent to the radial wall of the outer cannula 
     At  410 , a retractable tool actuator of the endoscopic instrument is operated. The retractable tool actuator may be attached to a retractable tool (e.g., blade) to cause the retractable tool to move along a tool axis. The cutting tool may extend in a direction parallel to a longitudinal axis of the endoscopic instrument. The retractable tool actuator may include a linear actuator. In some implementations, operating the retractable tool actuator includes receiving a control signal at the retractable tool actuator to cause the retractable tool actuator to move the retractable tool. The retractable tool actuator may control operation of the retractable tool based on the control signal. Operating the retractable tool may include moving the retractable tool in and out of a tool channel of the outer cannula along a surface of the sample desired to be resected. 
     At  415 , the sample may be retrieved. Retrieving the sample may include positioning an aspiration channel of the endoscopic instrument (e.g., an aspiration channel fluidly coupled to the inner cannula) adjacent to the sample to apply a vacuum force on the sample and pull the sample from the distal end of the endoscopic instrument to a proximal end of the endoscopic instrument.