Abstract:
An over-tube was developed for receiving and guiding endoscopic instruments into a patient&#39;s anus, through the colon, and into the peritoneum. The over-tube has a flexible sheath adapted for insertion into the anus through the colon and out the peritoneum of a patient. A stiffened region is used to protect the colonic wall from injury during insertion of medical instruments through the patient&#39;s lower gastrointestinal tract. The proximal end of the over-tube is surrounded by two narrow inflatable balloons on either side of the colotomy to keep the device in place with its lumen open into the peritoneum and further prevent leakage of insufflation. The device may comprise two channels, one for duel channel endoscopes and larger medical instruments or single lumen endoscopes, and an additional channel for surgical instruments. A distal valve prevents insufflation leakage, making the device especially useful in NOTES surgeries.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of prior filed International Application, Serial Number PCT/US2009/031674 filed Jan. 22, 2009, which claims priority to U.S. provisional patent application No. 61/022,655 filed Jan. 22, 2008 which is hereby incorporated by reference into this disclosure. 
     
    
     FIELD OF INVENTION 
       [0002]    This invention relates to surgical intubation. More specifically, the invention is an over-tube for endoscopic and minimally invasive surgery. 
       BACKGROUND OF THE INVENTION 
       [0003]    Laparoscopic surgical techniques have been developed in order to avoid large skin incisions associated with traditional surgery. Such minimally invasive surgical techniques have been evolving for more than 100 years, since Georg Kelling performed the first experimental laparoscopy in 1901. (Litynski, G. Endoscopic surgery, the history, the pioneers. World J. Surg. 1999 Aug;23(8):745-53). Currently, hybrid procedures combining flexible endoscopy and laparoscopy, such as intraoperative enteroscopy and laparoscopic-assisted endoscopic retrograde cholangiopancreatography, are performed in increasing numbers. (Ceppa, F., et al. Laparoscopic transgastric endoscopic retrograde endoscopy after Roux-en-Y gastric bypass. Surg. Obes. Relat. Dis. 3: 21-24 2007; Peters, M., et al. Laparoscopic transgastric endoscopic retrograde cholangiopancreatography for benign common bile duct structure after Roux-en-Y gastric bypass. Surg. Endosc. 16:1106 2002). 
         [0004]    Recently, natural orifice transluminal endoscopic surgery (NOTES) has been performed by entering the peritoneal cavity via the stomach, colon, vagina, or bladder. (Pearl, J., Ponsky, J., Natural orifice transluminal endoscopic surgery: past present and future. J Min. Acc. Surg. 3:2 43-46 2008; Wilk, P., U.S. Pat. No 5,297,536). NOTES has been extensively studied in animal models, with tubal ligation, gallbladder surgery, oophorectomy, hysterectomy, gastrojejunostomy, and splenectomy having been described. (Jagannath, S., et al. Peroral transgastric endoscopic ligation of fallopian tubes with long-term survival in a porcine model. Gastrointest. Endosc. 61: 449-453 2005; Experimental studies of transgastric gallbladder surgery: cholecystectomy and cholecystogastric anastomosis. Gastrointest. Endosc. 61: 601-606 2005; Wagh, M. et al., Survival studies after endoscopic transgastric oophorectomy and tubectomy in a porcine model. Gastrointest. Endosc. 63: 473-478 2008; Merrifield, B., et al. Peroral transgastric organ resection: a feasibility study in pigs. Gastrointest. Endosc. 63: 693-697 2006; Kantsevoy, S., et al. Transgastric endoscopic splenectomy: is it possible? Surg. Endosc. 20: 522-525 2006). These surgical procedures are promising advances, due to the potential to eliminate traditional surgical complications, like postoperative abdominal wall pain, wound infections, hernias, adhesions, and impaired immune function. (Wagh, M., Thompson, C. Surgery insight: natural orifice transluminal endoscopic surgery—an analysis of work to date. Gastr. &amp; Hept. 4:7 386-392 2007). Further, NOTES procedures may be performed under conscious sedation and not general anesthesia. (Pearl, J., Ponsky, J., Natural orifice transluminal endoscopic surgery: past present and future. J Min. Acc. Surg. 3:2 43-46 2008). The transluminal approach could be particularly important for morbidly obese patients and others at high risk for standard surgery. 
         [0005]    One surgical approach for NOTES involves intercolonic entrance, as the gastric wall and small intestine are relatively sterile. (Hochberger, Lamade, Transgastric surgery in the abdomen: the dawn of a new era, Gastrointestinal Endoscopy; 62(2): 293-296, 2005). In colonic endoscopy procedures, the endoscope must be straight for proper advancement of the endoscope through the colon. Advancing an endoscope through the colon is difficult due to a loop in the sigmoid colon and another at the transverse colon, and often results in a loop formation along the shaft of the scope. As known to those skilled in the art, failure to substantially straighten the loop in the sigmoid colon prior to continuing to advance the scope can cause enlargement of the loop, resulting in more difficulty in advancing the scope and patient pain and injury. 
         [0006]    As is well known, over-tubes are not easy to use and can cause complications such as perforation. Moreover, surgical instruments, such as needle scalpels, present hazards to internal organs. 
       SUMMARY OF THE INVENTION 
       [0007]    Despite the prevalence of specially configured endoscopes and splints to reduce sigmoid looping in order to improve the effectiveness and reduce the pain of colonic procedures, such as colonoscopy or NOTES, many operators still face significant difficulty and, on occasion, are unable to reach the small intestine due to looping of the sigmoid. As a result, therefore, what is needed is a device and a method of using that device that improves the use of an endoscope during a surgery by reducing the problems associated with insertion and advancement of the endoscope and instruments through the colon. 
         [0008]    Colonic gastrointestinal access of endoscopic instruments has unique problems not addressed with typical endoscopic procedures and instruments. A flexible over-tube of sufficient length to extend from the anus to proximal colon is disclosed herein. The device may be used intraluminally or advanced through the colonic wall and into the peritoneum. The over-tube sheaths and protects the colon throughout the procedure and may guide both a double channel gastroscope or a colonoscope as well as various other instruments through the colon and out the colonic wall into the peritoneum. The device avoids reintubation of the colon, promotes safe and easy access with increased efficiency and accuracy of insertion of the endoscope and other instruments and minimizes the risks of perforation and mucosal injuries and allows secure control of the colostomy. 
         [0009]    The over-tube has at least one flexible tube further comprising a proximal end, a distal end, and a longitudinal axis with at least two endoscopic channels. The endoscopic channels are located in the flexible tube, defining a first working channel and a second working channel. The working channels may be both located in one flexible tube, or dispersed in multiple flexible tubes so that each tube comprising at least one working channel. In certain embodiments, a plurality of flexible tubes is fused together. Specifically, a first fused tube is fused to a second fused tube along the longitudinal axis of the tubes. In other embodiments, additional tubes are also fused to the first and second tubes along the respective longitudinal axis of each tube. 
         [0010]    The over-tube is of sufficient size that the over-tube extends from the anus, up the proximal colon, and may extend through the colonic wall into the peritoneum. Over-tube lengths vary, but preferably are in 25, 50, 75, and 100 cm lengths. The over-tube has a length ranging from 25 to 100 cm in specific embodiments. The first fused tube has an outer diameter of between 8 to 12.6 mm in some embodiments of the invention. The first fused tube may further include an inner diameter of between 2.8-3.8 mm. The over-tube has an additional 10-12 mm channel. This channel is useful for inserting surgical instruments which move in tandem with the endoscope. 
         [0011]    The over-tube may be constructed of polyurethane, polyvinyl chloride, polytetrafluoroethylene, polyester, para-phenylenediamine and terephthaloyl chloride polymer, carbon fiber, meta-phenylenediamine and terephthaloyl chloride polymer, nylon, rubber, latex, silicone, polyisoprene, polystyrene and polybutadiene polymer, urethane, polyethylene, polyisoprene, ethylene propylene diene monomer, neoprene, polyurethane, polyvinyl chloride, and styrene butadiene. 
         [0012]    The tip of the over-tube is circumscribed by two narrowed inflatable balloons that are utilized on either side of the colostomy to keep the device in place with its lumen open into the peritoneum. A series of ring-shaped balloons are disposed on the distal end of the tube. Specific embodiments use two balloons at a distance such that the balloons fit on either side the colonic wall of a patient. In such embodiments, the balloons are placed on either side of the colonic wall of a patient and inflated, thereby pinning the distal end of the tube to the colonic wall. The over-tube may also include a ring-shaped balloon is disposed on the proximal end of the tube. In such embodiments, the balloon is placed proximal to the rectum and inflated, thereby pinning the proximal end of the tube to the patient&#39;s rectum. 
         [0013]    In specific embodiments, the distal end of the flexible tube or tubes is tapered, rounded, or adapted to accept a rounded mountable tip. The exterior surface of the flexible tube or tubes is smooth in certain embodiments. These alterations have the advantage of providing additional patient comfort during advancement and removal of the over-tube. 
         [0014]    The device has a valve at the distal opening to prevent leakage of peritoneal insufflation. The valve is at least one seal disposed in the lumen of the at least one flexible tube. In specific embodiments, the seals are affixed to the proximal end of the flexible tube. Further, the instrument seals may be made of one or more flexible compounds such as polyester, para-phenylenediamine and terephthaloyl chloride polymer, carbon fiber, expanded PTFE, meta-phenylenediamine and terephthaloyl chloride polymer, nylon, fiber glass, cotton, polypropylene and ceramic, rubber, latex, silicone, polyurethane, polyisoprene, polystyrene and polybutadiene polymer, urethane, polyethylene, polyisoprene, polyvinylchloride, ethylene propylene diene monomer, neoprene, and styrene butadiene. The seals may also be is coated a lubricant. Exemplary lubricants include hydrophilic polymer coatings, Teflon, thermoplastic, cyanoacrylate, parylene, plasma surface treatments, cornstarch powder, silicone oil, silicone grease, astroglide lubricants, mineral oil, glycerin, alcohol, saline, Teflon lubricants, Krytox lubricants, molybdenum disulfide lubricants, and graphite. However, other lubricants known in the art may be used. 
         [0015]    The over-tube may also include a stiffened region disposed along the longitudinal axis of the flexible tube or tubes, and may be 10 cm long. The length of the stiffened region may be varied, depending on the usage of the over-tube and patient anatomy. The stiffened region is constructed of any flexible material known in the art, such as polyester, para-phenylenediamine and terephthaloyl chloride polymer, carbon fiber, expanded PTFE, meta-phenylenediamine and terephthaloyl chloride polymer, nylon, rubber, latex, silicone, polyurethane, polyisoprene, polystyrene and polybutadiene polymer, urethane, polyethylene, polyisoprene, polyvinylchloride, ethylene propylene diene monomer, neoprene, polyurethane, polyvinyl chloride, and styrene butadiene. 
         [0016]    In a specific embodiment, the device allows for receiving and guiding endoscopic instruments into a patient&#39;s anus, through the colon, and into the peritoneum. The over-tube has a flexible protective sheath adapted for insertion into the anus through the colon and out in the peritoneum of a patient. It also has a proximal valve that prevents insufflation leakage. The device has a stiffened region that protects the colonic wall of a patient from iatrogenic injury as a duel channel gastroscope or colonoscope or medical instruments are inserted through the sheath and into the patient&#39;s lower gastrointestinal tract. The distal end of the over-tube is surrounded by two narrow inflatable balloons that are utilized on either side of the colotomy to keep the device in place with its lumen open into the peritoneum and further prevent leakage of insufflation. The device has two channels. One channel is provided for duel channel gastroscopes and larger medical instruments or single lumen endoscopes, and has an outer diameter ranging between 8.6 mm and 12.6 mm, and channel size of between 2.8 mm and 3.8 mm. The second channel has an outer diameter that ranges between 10 mm and 12 mm. The device is especially useful in NOTES surgeries. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    For a fuller understanding of the invention, reference should be made to the following detailed description, taken in connection with the accompanying drawings, in which: 
           [0018]      FIG. 1  is a side view of the overtube with two fused working channels. 
           [0019]      FIG. 2  is a cross section of the overtube at location A-A of  FIG. 1 . The two fused channels are depicted. 
           [0020]      FIG. 3  is a side view of the overtube of the present invention with two working channels. The overtube is depicted inserted in a patient&#39;s colon with the distal end advanced to the sigmoid colon. 
           [0021]      FIG. 4  is a longitudinal section of the overtube depicting the tapered distal end of the present invention. The tapered end is depicted optionally covered in a heat-shrink wrapping to round the distal end. 
           [0022]      FIG. 5  is a longitudinal section of the overtube depicting the endoscope/instrument seals within the proximal end of the present invention using a diaphragm seal. 
           [0023]      FIG. 6  is a longitudinal section of the overtube of the present invention. Depicted is an embodiment using a stiffened region with support webbing manufactured into the overtube walls. 
           [0024]      FIG. 7  is a longitudinal section of the overtube of the present invention. Depicted is an embodiment using a stiffened region using a wrapping the outside of the over-tube. 
           [0025]      FIG. 8  is an illustration of the overtube inserted in a patient&#39;s colon with the distal end advanced through the sigmoid colon, straightening the colon to allow easier passage of endoscopes and instruments through the overtube working channels. 
           [0026]      FIG. 9  is an illustration of the overtube inserted in a patient&#39;s colon with the distal end advanced to the surgical incision/entry site. Upon incision, the balloons on the distal end of the overtube are moved on either side of the colon wall and inflated to fix the over-tube to the colon and prevent retraction or advancement during surgery. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0027]    Disclosed is an over-tube, which is useful in performing various medical procedures, such as NOTES surgery utilizing the colon as an entry point. The device may decrease the total physician and support staff time spent on a procedure, resulting in a benefit to the patient&#39;s health and overall prognosis as a result of a decrease in potential procedure complications and reduced time under anesthesia. The device may also result in a net revenue increase by decreasing the overall procedure time, reducing potential patient complications, and reducing overall recovery time and associated costs. 
         [0028]    As used herein, the term “endoscope” or “scope” is used to refer to an endoscope, laparoscope, sigmoidoscope, proctoscope, colonoscope, or other types of medical endoscopes. As known to those skilled in the art, a typical endoscope generally comprises a connecting tube, a handle and an insertion tube (the part inserted into the patient). In referring to the opposite ends of the scope or the over-tube of the present invention, the “proximal end” refers to that part of the scope or over-tube which is closest to the operator or physician endoscopist (hereinafter collectively referred to as “operator”) performing the procedure, and the “distal end” refers to that part of the scope or over-tube farthest from the operator or physician endoscopist. Although medically the rectum is generally not considered to be part of the colon, which includes the sigmoid colon, descending colon, transverse colon and ascending colon, for purposes of this disclosure general references herein to the term “colon” include the rectum. 
         [0029]    The term “over-tube” is used to refer to a generally elongated hollow tubular member that is adaptable for receiving a medical instrument, such as an endoscope, therein to facilitate movement of the scope through the colon. 
         [0030]    Endoscopic over-tube  10  is a generally tubular flexible protective sheath comprising a proximal end  11  and a distal end  12 . The length of over-tube  10  is in the range of 25-100 centimeters. The over-tube consists of two fused channels, endoscope channel  13  and instrument channel  14 , as seen in  FIG. 1 . Endoscope channel  13  has an outer diameter ranging between 8.0 millimeters and 12.6 millimeters, and channel size of between 2.8 millimeters and 3.8 millimeters. Instrument channel  14  has an outer diameter that ranges between 10 mm and 12 mm. Endoscope channel  13  and instrument channel  14  extend through over-tube  10  and facilitate passing an endoscope through over-tube  10 . Distal balloon set  15  comprises a plurality of inflatable balloons disposed on the distal end of the over-tube and adapted to fit on either side of the colostomy. Proximal balloon  18  is disposed on the proximal end of over-tube  10  and is also inflatable. 
         [0031]    At least portion of over-tube  10  is laterally flexible, allowing over-tube  10  to flex substantially without kinking during advancement of over-tube  10  through a colon. As illustrated in  FIG. 1 , over-tube  10  is comprised of a plurality of fused working channels, endoscope channel  13  and instrument channel  14 , extending along the entire length of the over-tube  10  from the proximal end  11  to the distal end  12 . The fused channel configuration of over-tube  10  allows lateral flexation of the over-tube in one direction, transversely in relation to the fused channel. 
         [0032]    Over-tube  10  is suitable for insertion into the rectum and into the colon of a patient and defines a series of fused generally circular or cylindrical bores  16  throughout its length. Bore  16  has a diameter generally in the range of about 5 to about 9 centimeters. Over-tube wall  17  is generally in the range of 3.0 to 10.0 millimeters, seen in  FIG. 2 . 
         [0033]    Over-tube  10  is constructed of a soft flexible material such as polyurethane or polyvinyl chloride. Distal end  12  of over-tube  10  is soft and flexible, allowing for insertion of over-tube  10  along the lumen of the colon and around the sigmoid colon and transverse colon without irritating the colonic peritoneum, seen in  FIG. 3 . Additionally, distal tip  20  of over-tube  10  may include a tapered portion  21  on both endoscope channel  13  and instrument channel  14 . Over-tube  10  may also be constructed of a material which is thermally stable for use in a colon. In this case the thermally stable material used for the over-tube  10  is polytetrafluoroethylene (PTFE). However, over-tube  10  must be constructed of sufficiently pliable material such that over-tube  10  is not overly stiff. Insertion of over-tube  10  into a colon, and navigation of the over-tube through a colon requires flexible or pliable materials to permit a surgeon to utilize the over-tube without undue difficulty and without causing undue discomfort to a patient. However the over-tube must maintain a minimum threshold of stiffness once inserted into the colon to prevent sigmoid loops from reforming as an endoscope or surgical instrument is passed through endoscope channel  13  or instrument channel  14 . 
         [0034]    The thickness of over-tube wall  17  is gradually decreased along tapered portion  21  such that the wall is thinnest at distal end  12  of the over-tube. The reduced wall thickness of over-tube wall  17  makes the distal tip extremely soft and flexible, facilitating advancement of over-tube  10  through the colon. Over-tube  10  utilizes an additional section of heat-shrink tubing  25  fixed to the exterior surface of over-tube  10  at distal end  12  of the over-tube, seen in  FIG. 4 . Distal end  12  of the heat-shrink tubing is rolled inwardly, and the heat-shrink tubing is positioned around the distal end  3  of the over-tube  10 , partially overlapping distal end  12 . The heat-shrink tubing is partially inserted into the lumen of the over-tube, such that the heat-shrink tubing extends around the distal end  12  of the over-tube and partially covers the lumen of endoscope channel  13  or instrument channel  14 , thereby producing a rounded tip at the distal end  12 . Rounded distal end  12   a  ensures that there are no sharp edges at the distal end of over-tube  10 , which prevents traumatic advancement of the over-tube through a colon. Alternatively, distal end  12  may be adapted to accept a rounded mountable tip, such as a compression fitting. The heat-shrink tubing has a smaller diameter than over-tube  10 , such that the heat-shrink tubing is stretched into position around distal end  12 . In some embodiments, the distal edge of the heat-shrink tubing is rolled to form a rounded proximal end  12 , seen in  FIG. 8 , and heat is applied to shrink the heat-shrink tubing down onto the over-tube and fix the heat-shrink tubing to the exterior surface of over-tube  10 . 
         [0035]    Flexible instrument seal  30  and endoscope seal  31  are provided near proximal end  11  of over-tube  10  for sealing between the over-tube  1  and an endoscope or surgical instrument extending through endoscope channel  13  or instrument channel  14 , as seen in  FIG. 5 . Instrument seal  30  and endoscope seal  31  may be constructed of a tubular sheath of film, in this case silicone, material, which is fixed to an exterior surface of the over-tube at proximal end  11  using heat-shrink tubing. As illustrated in  FIG. 5 , the tubular sheath extends inwardly at the proximal end  11  of the over-tube for sealing between over-tube  10  and an endoscope or surgical instrument, and then proximally to proximal end  11 . 
         [0036]    The flexible nature of instrument seal  30  and endoscope seal  31  enables the seals to adapt to the size of the endoscope extending through endoscope channel  13 . In this manner, a secure, effective seal between the over-tube  10  and an endoscope is achieved regardless of the size diameter range of an endoscope. In addition, the seals possess a low profile, which facilitates easier passage of the endoscope through the over-tube, minimizing discomfort to the patient. 
         [0037]    In some embodiments, stiffened region  21  is provided in over-tube  10 , located a first distance D 1  from the proximal end of over-tube  10 , seen in  FIG. 6 . The first distance generally equals or approximates the sigmoid loops, approximately 10 centimeters from the proximal end for an average adult patient. From the position defined by D 1 , the stiffened region  21  extends distally a second distance D 2  along the over-tube. Second distance D 2  generally equals approximately 10 centimeters for an average patient. However, when adapted for pediatric use, the distance may be varied to complement to physical dimensions of the pediatric patient&#39;s colon. 
         [0038]    Stiffened region  21  is constructed by wrapping the outside of over-tube  10  with flexible material, such as polyurethane or polyvinyl chloride, or providing heat-shrink wrapping  24 , as seen in  FIG. 7 . The layer provides an increased stiffness and thickness along the portion of the over-tube and generally has a thickness ranging between 1-2 millimeters. The material for stiffened region  21  is affixed to over-tube  10  by conventional fastening techniques such as vulcanization, use of adhesives, hot pressing, etc. Alternatively, stiffened region  21  may be constructed by wrapping the inside of over-tube  10  with the flexible material and affixed to the wall of the over-tube lumen. In another embodiment, the over-tube  10  may be extruded, formed or molded such that the portion of over-tube  10  has a wall thickness greater than the wall thickness of the remainder of over-tube  10 , thereby creating stiffened region  21 . This type of manufacturing process would eliminate the need for thickening over-tube  10  by affixing flexible material to the over-tube. In other alternate embodiments, stiffened region  21  may be constructed by incorporating longitudinal ribbing  22  within the wall of the portion of over-tube  10  designated by D 2 . 
         [0039]    In another alternative embodiment, stiffened region  21  may be generated by providing a stiffer material than the remainder of the over-tube in the region designated by D 2 . In this construction, stiffened region  21  is attached to the more flexible portions of over-tube  10  by conventional fastening techniques such as vulcanization, use of adhesives, hot pressing, or other techniques known in the art. This construction allows over-tube  10  to have a constant outer and inner diameter throughout its length. Exterior surface  19  of over-tube  10  may be smooth, as seen in  FIG. 2 , thereby reducing the discomfort and/or pain experienced by the patient during the endoscopy procedure. In some embodiments, support webbing  23  is embedded in over-tube  10 , seen in  FIG. 6 , permitting over-tube  10  to maintain kink-resistant properties. Support webbing  23  may be any suitable form known in the art, such as a mesh, or a braided material. In another alternative the composite over-tube may have a layered construction. 
         [0040]    Lubricants may be used to ease insertion of the over-tube into the colon of a patient and/or may be used around the interior on the over-tube lumen to allow ease of passage of the over-tube  10  relative to an endoscope and/or relative to a colon. Exemplary lubricants include silicone or polytetrafluoroethylene (PTFE). Alternatively, the lubricant may be provided as an integral component of the over-tube  10 , such as by fixing a silicone coating to the over-tube. 
         [0041]    Over-tube  10  may be inserted into the colon prior to, or concurrently with, an endoscope. Where the over-tube is concurrently inserted, the endoscope is advanced into the one of the plurality of working channels, such as endoscope channel  13 , until the endoscope abuts the distal end of over-tube  10 . A typical colon  50  is illustrated in  FIG. 3 , in which rectum  52  leads from anus  51  to sigmoid colon  54 . Descending colon  53  leads from sigmoid colon  54  to transverse colon  55 . The patient is prepared for surgery, which may include applying a local anesthetic to numb the rectum and to minimize patient discomfort. Distal end  12  of the over-tube  10  is inserted through anus  51  into rectum  52 , and the over-tube is advanced into sigmoid colon  54 . Because distal end  12  is flexible and rounded it is advanced through the curvature of the colon with minimal discomfort. As the over-tube advances through sigmoid colon  54 , a loop may form in the sigmoid colon, which results in stretching of the mesentery to which sigmoid colon  54  is attached. When distal end  12  of over-tube  10  reaches the proximal end of descending colon  53 , distal end  12  may be anchored in descending colon  53 , and sigmoid colon  54  is straightened by manipulating the over-tube, for example by rotating the over-tube 90 degrees. When the sigmoid colon has been straightened, the anchor is released. Alternatively, the over-tube is rotated in descending colon  53  without anchoring. 
         [0042]    With over-tube  10  extended through the straightened sigmoid colon  54 , seen in  FIG. 8 , the endoscope may then be advanced further through the descending colon  53  and into transverse colon  55 . The over-tube acts as a splint to maintain the sigmoid colon in the straightened configuration and ensures that further advancement of the endoscope through the descending colon and into the transverse colon is possible by preventing loops from reforming in the sigmoid colon. In this manner, over-tube  10  acts as a guide for the endoscope or surgical instrument and minimizes the pain or discomfort experienced by the patient during this procedure. 
         [0043]    Over-tube  10  also acts as a sheath between the endoscope or surgical instrument and the colon and prevents shearing off of any parts of the colon wall, or puncturing the colon wall, or any other damage to the interior wall of the colon during advancement or retraction of instruments and endoscopes through the colon. This allows the surgeon to efficiently introduce new instruments to the endoscopic surgical site rapidly and with reduced concern for colon damage. Further, the over-tube includes instrument seal  30  and endoscope seal  31  which seal the lumen of the over-tube and ensure air does not leak through the over-tube, thereby allowing the surgeon to induce and maintain pneumoperitoneum. In embodiments using stiffened region  21 , the region is disposed to substantially reside in sigmoid colon  54  during the operation and helps insulates the colon from irritation caused by insertion and retraction of medical instrumentation through the over-tube during surgery. 
         [0044]    Upon incision into the colon, over-tube  10  is advanced into the colostomy and positioned such that colon wall  54  is disposed between each distal balloon on distal balloon set  15 . Distal balloon set  15  is then inflated, as depicted in  FIG. 9 , thereby fixing the over-tube to the colon and preventing retraction or advancement of the over-tube during surgery. Proximal balloon  18  is also inflated to fix the proximal end of over-tube  10  during surgery. Medical instrumentation such as endoscopes, evacuation tubes, lavage tubes, etc., is then advanced through cylindrical bores  16  of the over-tube. During surgery, the endoscope advantageously may be used in conjunction with other surgical instruments. With the endoscope disposed in endoscope channel  13 , additional instruments may be quickly and easily passed to access any point in the colon using instrument channel  14 , which provides a large working channel through the colon through which any instrument may be advanced. Rapid and less painful exchange of instruments and/or endo scopes is thus facilitated by over-tube  10  because there is no contact between the instruments/endoscopes and the inner wall of the colon during insertion or withdrawal of the instruments/endoscopes. In addition, instrument channel  14  has a much larger diameter than the diameter of a typical endoscope working channel. Thus, larger instruments may be used during a surgical procedure with the over-tube  10 . Larger samples may also be removed using the over-tube  10 . 
         [0045]    After the surgery is completed, the medical instrumentation is removed from over-tube  10 . Distal balloon set  15  and proximal balloon  18  are deflated and over-tube  10  is removed from the colon of the patient. 
         [0046]    In the preceding specification, all documents, acts, or information disclosed does not constitute an admission that the document, act, or information of any combination thereof was publicly available, known to the public, part of the general knowledge in the art, or was known to be relevant to solve any problem at the time of priority. 
         [0047]    The disclosures of all publications cited above are expressly incorporated herein by reference, each in its entirety, to the same extent as if each were incorporated by reference individually. 
         [0048]    While there has been described and illustrated specific embodiments of an endoscopic over-tube, it will be apparent to those skilled in the art that variations and modifications are possible without deviating from the broad spirit and principle of the present invention. It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.