Abstract:
An improved surgical dilator extractor is introduced into the abdominal cavity through a trocar cannula and expanded, forming a tissue receiving space, at the distal end. The tissue receiving space is enlarged by passing a grasper through a lumen of the dilator extractor to interact with a guide surface on the interior of dilator extractor to expand a dilator portion having a single leaf beyond the natural resiliency of the leaf. The tissue being extracted is then manipulated into the space with the grasper. The tissue is then removed from the cavity by the surgeon applying a force onto the dilator extractor that insures the elongation of the tissue and temporarily dilates the entry wound to the extent necessary for the tissue to be removed. Alternative embodiments of the surgical dilator extractor and related instrument tool sets and methods for the use thereof also are disclosed.

Description:
RELATED APPLICATIONS 
   This application claims the benefit of U.S. Provisional Application No. 60/416,665, filed Oct. 7, 2002; U.S. Provisional Application Nos. 60/424,752; 60/424,754; and 60/424,755, each filed Nov. 8, 2002; U.S. provisional Application Nos. 60/425,506; 60/425,522; and 60/425,523, each filed Nov. 12, 2002; and U.S. Provisional Application No. 60/439,759, filed Jan. 13, 2003, all of which are incorporated by reference herein. 

   BACKGROUND OF THE INVENTION 
   The present invention relates generally to mechanical devices and methods used in laparoscopic surgical procedures to remove organs and excised tissue from internal body cavities. 
   It will be appreciated by those skilled in the art that the use of bags or pouches to remove organs and large tissue specimen during laparoscopic surgical procedures is well known. As described, for example, in U.S. Pat. No. 5,147,371 a pouch is introduced into the abdominal cavity for retrieving gallstones and tissue. The bag is opened and closed using a wire loop as a drawstring. In U.S. Pat. No. 5,192,284 an expandable bag is inserted into the abdominal cavity through a trocar cannula. The bag described in the &#39;284 patent is made of a memory material that is rigid enough to support itself. The bag expands and remains open when it is inserted into the abdominal cavity through the cannula. U.S. Pat. No. 5,480,404 describes a pouch for extracting tissue that is opened and closed by a ratchet mechanism. U.S. Pat. No. 5,341,815 employs shape memory effect metal to open the bag upon insertion through a trocar. U.S. Pat. Nos. 5,681,324 and 5,971,995 describe similar bags and pouches. 
   The pouches described in these patents are useful in containing any bile or gallstones that might otherwise spill into the abdominal cavity during extraction of a torn gallbladder. These types of devices, however, suffer from at least three problems. Since such devices are closed on the distal end, air inside the enclosure tends to balloon the pouches or bags during the extraction process thereby increasing the size or not allowing a full collapse of a bag as it is removed from the wound. Additionally, when the tissue is larger than the wound size, it is forced to the bottom of the bag as the radial force of the wound acts on the tissue during extraction. This also increases the size to which the wound must be dilated for removal of the tissue. Tapering the bags toward the distal end helps somewhat to lessen this effect, but the result is not optimal and does not fully address the problem of air trapped in the bag. Finally, the work required to remove a gall bladder is equal to the extraction force times the distance over which the force is required to act plus any heat generated by friction. For example the work required to remove a bagged gallbladder with a 30 mm diameter stone is the same as the work required to extract the same gall bladder that is contained in a rigid shallow cone with a maximum diameter of 30 mm (neglecting friction differences). The peak force for removal is much higher, however, for the bagged gallbladder since the force is required to act over a much smaller distance. Since it is desirable to minimize the forces required to extract a gallbladder owing to material and human limitations, the gallbladder should be, by way of example only, contained in a rigid shallow cone rather than a flexible bag. 
   Since the goal of laparoscopic surgery is to become less invasive by using smaller entry wounds, the prior art is of limited value for removing large specimens through, for example, 5 mm wounds. When the user pulls on the bag in an attempt to remove it through a small trocar entry wound, the specimen is forced to the bottom of the bag by the radial forces exerted by the abdominal tissue or by the forces exerted on the bag from the cannula, thus creating a large lump that is often incapable of passing through the wound without tearing the bag. The use of this type of extraction bag in these cases often requires de-bulking of the specimen so that the bagged specimen pieces are of such a size that the bag can be extracted through the trocar entry wound, typically 10–12 mm. This is a time consuming process that is not always successful since, for example, large stones may be inside a gallbladder and the process usually necessitates the pathologic examination of the tissue specimen. As an alternative to de-bulking, the wound size may be increased with a scalpel to allow the extraction. This approach, however, lessons the advantage of the laparoscopic surgery. Additionally, these types of extraction bags add undue complexity to the procedure since they require the use of two ports, one for the bag and a second for a grasper to retrieve the tissue and put it into the bag. 
   U.S. Pat. Nos. 5,190,561 and 5,370,647 to Graber disclose several embodiments of laparoscopic extraction devices that allow a grasper to be inserted into the center of an extractor device so that tissue can be more easily manipulated into the inside of the extractor. In each of the embodiments the extractor is introduced into the abdominal cavity through a specially designed trocar cannula equipped with setscrews to lock the extractor to the trocar cannula. Upon exiting the distal end of the cannula, the distal end of the extractor expands, much like an umbrella. A grasper is then introduced into the abdominal cavity through a lumen in the extractor. The specimen is grasped and pulled into the expanded open distal end of the extractor, a cone-shaped device. The grasper is then locked to the cannula using the setscrews. The proximal end of the extractor is equipped with a handle, which is used to pull the extractor and the tissue through the cannula. As the handle is pulled upward “ . . . the enveloping means collapses around the tissue and returns to its pre-deployment.” The enveloping means of Graber &#39;647 is relied on to compress the tissue to a size that allows it to be drawn into a hollow tubular shroud 610 (see FIG. 13 of Graber &#39;647). Thus, the device is not optimally designed to deal with a tissue specimen that will not compress to a point so that it can be drawn into the shroud. 
   The extractor of Graber &#39;647 also has several other disadvantages. The Graber &#39;647 device is ill-suited for use with standard trocars because it utilizes setscrews, which are not generally available on trocars in current use, to lock it to the trocar. The Graber &#39;647 device also utilizes an expensive locking mechanism to lock the grasper to the extractor. In addition, most abdominal laparoscopic procedures are performed with the abdominal cavity insufflated with carbon dioxide. The lumen in the extractor of Graber &#39;647 has no provision for sealing and thus when the extractor is placed through the seal of the trocar, the abdomen will loose its carbon dioxide pressure through the lumen of the extractor. 
   The Graber &#39;647 device is removed from the body cavity by an exertion force on the handle of the device. This unduly places rotational and shear forces on the extractor-grasper lever lock and the extractor-trocar setscrews because of the vigorous rotational manipulation required to remove it from the abdominal wall. 
   One of the extractor covers disclosed in the Graber &#39;647 patent is made from “a sturdy waterproof, stain resistant fabric such as treated sailcloth or duck cloth.” These materials are thick, bulky, and generally not suited for extractors for use with less invasive trocar cannula such as 5 mm and smaller devices. In particular, such covers require multiple folds in order for the extractor to pass through a small-bore cannula. FIG. 24 of the Graber &#39;647 patent discloses a thin “baggie,” however, it requires thick leaves 608 and a plunger rod 606 to compress the tissue. The combination and thickness of these features is unduly complicating and makes the Graber device ill-suited for small cannulas. 
   The embodiment disclosed in FIG. 12 of the Graber &#39;647 patent teaches the use of a flexible, waterproof web material with an opening mouth so that tissue can enter the rib portion 510. While this embodiment partially solves the spillage problem it unduly complicates manipulating the tissue inside the extractor and is overly complex in that the extractor cover and the spillage compartment are made of two separate pieces which must be joined by sewing, heat treating, or welding. 
   Graber also discloses a multi-leaf rigid cover that is pinned to a hollow elongated shank. The leaves are rolled into a generally cylindrical shape inside the shank in an un-deployed state and expanded into a generally conical shape in a deployed state. An extraction dilation device having a single leaf is desirable owing to its simplicity. Graber does not teach a method or mechanism for attaching a single leaf to the shank since fixedly pinning a single-leaf sheet to the shank results in buckling of the cone when attempting to roll it into a generally cylindrical shape for insertion within a tube. 
   Laparoscopic removal of the gallbladder has, heretofore, entailed the use of four entry cannula, typically two of which are 10 to 12 mm in diameter and two of which are 5 mm in diameter. The two 5 mm ports are used to accept instruments such as scissors, graspers, electro-surgery probes, and suction/irrigation devices. The 10 to 12 mm ports are employed to allow the use of instruments such as a 10 mm endoscope attached to a camera for viewing the surgical field or a clip applier for ligating vessels and ducts, and to permit the removal of a gallbladder following its excision. 
   In an effort to make the procedure less invasive, 5 mm clip appliers have been developed, such as described by Shipp et al. in U.S. Pat. No. 5,858,018, the disclosure of which is incorporated by reference herein. The 5 mm clip applier allows the conversion of one of the two 10 to 12 mm ports to a third 5 mm port. The remaining 10 to 12 mm port prior to this invention has been required to accept 10 mm endoscopes and to permit the removal of the gallbladder, usually through the umbilicus port site. New bright 5 mm endoscopes coupled with more sensitive cameras have been developed that are quite acceptable substitutes for the prior art camera systems. These developments leave gallbladder removal through a 5 mm or smaller port as the last obstacle to the full conversion of the process to four much less invasive 5 mm ports. The conversion from two 10 to 12 mm trocars and two 5 mm trocars to four 5 mm trocars lowers the total entry wound area by 50 percent, which greatly reduces bleeding and post surgery incisional herniation at the wound sites. 
   What is needed then is a simple, inexpensive device and an easy to use method for rapid removal of tissue, such as a gallbladder, from a wound site that has an opening size that is smaller than the size of the specimen and does not require substantial secondary operations such as grinding the specimen into smaller pieces or significantly enlarging the wound size. Also needed is a simple, rigid single-leaf dilator extractor that is attached to a hollow shank such that the leaf may easily be rolled into a shape exhibiting a minimal diameter for insertion into a small trocar cannula, for example, 5 mm. Preferably, the deployed dilator extractor is sufficiently rigid so as to provide a smooth, shallow angled cone shape so that the force required to remove the tissue is minimized. Preferably, the dilator extractor is self-deployable to a sufficient base diameter upon exiting the cannula, even after prolonged storage in a rolled-up or un-deployed state. 
   SUMMARY OF THE INVENTION 
   The present invention in one embodiment is directed to an expandable dilator extractor that expands upon entry into the abdominal cavity for acceptance of a tissue specimen using a grasper to pull the specimen into the interior of the dilator extractor. The construction of the dilator is such that when a surgeon places an upward force, away from the surface of the abdomen on the deployed dilator, it minimizes the cross section of the tissue by closing a cone about the specimen, and thus minimizes the wound dilation requirement. The resulting elongated conical shape forces the trocar puncture wound to expand to allow the larger specimen to be extracted with a minimum of tearing or otherwise permanently enlarging the wound. The cone angle is minimized to provide the maximum mechanical advantage and thus minimizes the force necessary for the surgeon to exert on the device for extraction. 
   A preferred embodiment of the extractor includes a body having a leading end, a trailing end, a lumen between the leading and trailing ends, and a mid-longitudinal axis passing through the lumen of the body. The extractor also includes a dilator at the leading end of the body that is movable between an unexpanded position and an expanded position. The dilator has a single leaf adapted to be rolled at least in part around the mid-longitudinal axis of the extractor. The dilator has a guide surface configured to engage an instrument inserted through the lumen. The guide surface is adapted to move at least a portion of the dilator away from the mid-longitudinal axis of the extractor upon engagement with the instrument. 
   Another preferred embodiment of the extractor includes a body having a leading end, a trailing end, a lumen between said leading and trailing ends, and a mid-longitudinal axis passing through the lumen of the body. The extractor also includes a dilator at the leading end of the body that is movable between an unexpanded position and an expanded position. 
   The extractor also includes a collar that has an opening and is movable relative to the body along the mid-longitudinal axis of the extractor. The body is adapted to pass through the opening in the collar. A retainer is attached to the collar. The retainer is adapted to retain the dilator in the unexpanded position until the body passes through the opening in the collar to move the dilator towards the expanded position. 
   Another embodiment of the present invention is also directed to a surgical tissue collection bag for removing tissue from an animal or human body cavity. The bag includes a top, a bottom, and at least one side between the top and the bottom. The top has an opening with a perimeter. The bag also includes a resilient expansion member that is movable between an unexpanded position and an expanded position. The expansion member is positioned around at least a portion of the opening. The expansion member is biased toward the expanded position. 
   Yet another embodiment of the present invention also is directed to a method for removal of excised tissue with minimal force. The method includes providing an extractor having a dilator movable between an unexpanded position and an expanded position. The dilator is made of a material that is biased at least in part toward the expanded position. The extractor is inserted through a cannula and at least in part into the body cavity. The dilator is released to move at least in part toward the expanded position. A portion of the extractor is engaged with an instrument to further move the dilator toward the expanded position. Tissue is removed from the body cavity. 
   In another embodiment the present invention includes a method of removing tissue by placing the tissue in a leak-proof bag and inserting the bagged specimen into a deployed dilator extractor prior to extraction. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a diagrammatic view of a grasper, a dilator extractor, and a cannula in accordance with one embodiment of the present invention. 
       FIG. 2  is a partial side sectional view of the dilator extractor of  FIG. 1  inserted in the cannula of  FIG. 1 . 
       FIG. 3  is a partial side elevation view of the leading end of the dilator extractor of  FIG. 1  in an expanded position. 
       FIG. 4  is a bottom plan view along line 4—4 of  FIG. 3 . 
       FIG. 5  is a sheet metal layout of the dilator extractor of  FIG. 1  prior to being rolled and formed into a conical shape. 
       FIG. 6  is a perspective view of a dilator extractor in accordance with another preferred embodiment of the present invention. 
       FIG. 7A  is a perspective view of a tissue collection bag with extension arms in accordance with another preferred embodiment of the present invention. 
       FIG. 7B  is a top view of one of the extension arms of  FIG. 7A . 
       FIG. 8  is a side elevation view of a grasper, dilator extractor, and cannula inserted in the abdominal wall of a patient, the grasper being inserted in the dilator extractor, the dilator extractor being inserted in the cannula, the dilator extractor and cannula being shown in cross section with the dilator extractor in the expanded position. 
       FIG. 9  is a side elevation view of a syringe, grasper, dilator extractor, and cannula inserted in the abdominal wall of a patient, the grasper being inserted in the dilator extractor, the dilator extractor being inserted in the cannula, the dilator extractor and cannula being shown in cross section with a tissue specimen being aspirated in accordance with the instrumentation and method of the present invention. 
       FIG. 10  is a partial side elevation view of the grasper, dilator extractor, and cannula of  FIG. 9  being withdrawn from the abdominal cavity with the tissue specimen in accordance with the instrumentation and method of the present invention. 
       FIG. 11  is a side elevation view of a grasper and cannula with another embodiment of a dilator extractor of the present invention having tissue-engaging protrusions being withdrawn from the abdominal cavity with the tissue specimen. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Reference will now be made in detail to the present preferred embodiments (exemplary embodiments) of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
     FIG. 1  shows a tool set having a cannula  100 , a dilator extractor  200 , and a grasper  300 . Grasper  300  is insertable in dilator extractor  200 , which in turn is insertable in cannula  100  to form a multi-coaxial assembly for use in laparoscopic surgery. An example of a tool set suitable for use in laparoscopic surgery is described in co-pending U.S. application Ser. No. 10/047,122, filed Jan. 15, 2002, which is incorporated herein by reference. 
   Referring to  FIGS. 2–5  and  8 , dilator extractor  200  is inserted into a pressurized abdominal cavity  60  through the abdominal wall of a patient. Dilator extractor  200  enters through valve  102  at trailing end  106  of cannula  100 . 
   Dilator extractor  200  includes a body  202  having a leading end  204 , a trailing end  206 , a mid-longitudinal axis L, and a lumen  208 . Body  202  includes a dilator  210  at leading end  204  that is movable between an unexpanded position, shown in  FIG. 2 , and an expanded position, shown in  FIG. 8 . Trailing end  206  preferably includes a depth-limiting protrusion in the form of shoulder  207 . Shoulder  207  is adapted to limit the deployment expansion of the cone of dilator  210 . 
   When the trailing end portion of dilator  210  clears leading end  104  of cannula  100 , dilator  210  expands to the expanded position preferably owing in part to the natural tendency of dilator cone  216  to unroll, thus forming a truncated conical-shaped tissue receiving space  214 , enclosed by dilator cone  216 . 
     FIG. 2  shows dilator extractor  200  before dilator  210  clears leading end  104  of cannula  100 . Dilator  210  may be preserved in the unexpanded position because of the inner diameter of cannula  100 . Dilator cone  216  is preferably wrapped upon itself to allow the passage of dilator extractor  200  in the unexpanded position through cannula  100 . 
   In a preferred embodiment, retainer  218  maintains dilator extractor  200  in the unexpanded state. One suitable retainer is straw-shaped and encircles dilator  210 . Retainer  218  extends toward trailing end  206  of dilator extractor  200  terminating into a graspable surface grip  220  proximate trailing end  206 . The composition of retainer  218  is such that it is strong enough to restrain the spring forces of dilator  210 , yet an upward force on graspable surface grip  220  will cause retainer  218  to peel open allowing dilator  210  to expand. By way of example, a suitable strength welded seam in a polyurethane film can accomplish such a peeling feature. 
   In one preferred embodiment a conical section  216  of dilator  210 , as best shown in  FIGS. 3–5 , is preferably made of a laminated, rigid, material that will allow it to be rolled and contained in cannula  100  prior to expansion of dilator  210  of dilator extractor  200 . Exemplary materials include plastic and metal, such as series  300  stainless steel. Conical section  216  is preferable a single leaf. A single leaf is advantageous for increasing the strength of conical section  216  as well as reducing the number of moving parts during the expansion of dilator  210 . 
   Conical section  216  includes an inner surface  228  and an outer surface  230 . Outer surface  230  of dilator cone  216  preferably has a low coefficient of friction, such as a PTFE (polytetrafluoroethylene) coating. Inner surface  228  preferably has high coefficient of friction, such as a sand blasted or otherwise roughened surface. It will be appreciated by those skilled in the art that other materials are suitable for providing a coefficient of friction that is higher on inner surface  228  than outer surface  230  and are within the scope of the present invention. Preferably, the coefficient of friction of inner surface  228  is in the range of 0.5 to 1.0. The low friction outer surface  230  of conical section  216  minimizes the force required for extraction while the high friction inner surface  228  provides a gripping force on the tissue surface area and thereby minimizes the force transferred to the grasper/tissue interface during the dilation extraction process. The dilation forces acting on the dilator require that the tensile strength of conical section  216  is adequate to withstand the friction force exerted by the tissue on inner surface  228 . While a differential coefficient of friction is preferred, the present invention is not so limited. For example, inner surface  228  may be smooth. 
     FIGS. 3 and 4  show dilator  210  in the expanded position. Once dilator  210  of dilator extractor  200  is in the expanded position as depicted in  FIG. 8 , grasper  300 , in a preferred embodiment, is inserted through channel or lumen  208 , into tissue space  214 , and into cavity  60 . 
     FIG. 5  shows sheet metal layout of the present invention having conical section  216  of a preferably thin, rigid material to which shank  250  is spot welded at locations  254  along a first edge  256  of conical section  216 . Shank  250  has a proximal end  258  and a distal end  260 . Shank  250  preferably includes a cut-out portion  262  near proximal end of dilator  210 . Cut-out portion  262  preferably has a guide surface  252  configured to contact and interact with grasper  300  to provide force to bend shank  250  so that grasper  300  is deployed through the center of conical section  216 . Cut-out portion  262  assists in permitting shank  250  to bend when dilator  210  moves from the un-deployed position to the deployed position while centering conical section  216  along mid-longitudinal axis L of dilator  200 . It is understood that guide surface  252  may be shaped in a variety of ways while still remaining within the scope of the present invention. For example, guide surface  252  may be a notch, indentation, projection, or other type of surface irregularity or deviation configured to interact with an instrument inserted through body  202 . It is further understood that instead of a shank, the guide surface may be formed integral with the interior of dilator  210 . 
   Distal end  260  of shank  250  is configured as a key-way to interact with a key used to roll dilator  210  into a generally cylindrical shape so that first and second edges  256 ,  264  overlap. Distal end  260  may be angled from the interior of dilator  210  for easier access with the key. 
     FIG. 6  shows a dilator extractor  200 ′ in accordance with another preferred embodiment of the present invention. Dilator extractor  200 ′ has a leading end  204 ′ and a trailing end  206 ′. Leading end  204 ′ includes a dilator  210 ′ with a retainer  218 ′ wrapped therearound. Trailing end  206 ′ includes a shoulder  207 ′, a knob  222 ′, and a portion  213 ′. Located between leading and trailing ends  204 ′,  206 ′ is a ring or collar  209 ′. Retainer  218 ′ is preferably attached to ring  209 ′ at bottom surface  215 ′ of ring  209 ′. 
   Dilator extractor  200 ′ is configured so that retainer  218 ′ is removed during the insertion of dilator extractor  200 ′ into cannula  100 . For example, while inserting dilator extractor  200 ′ into cannula  100 , bottom surface  215 ′ of ring  209 ′ comes into contact with trailing end  106  of cannula  100 . Continued insertion of dilator extractor  200 ′ into cannula  100  causes trailing end  206 ′ of dilator extractor  200 ′ to move toward ring  209 ′. Because retainer  218 ′ remains attached at bottom surface  215 ′, retainer  218 ′ is removed from dilator  210 ′ as dilator  210 ′ is further inserted into the cannula. Once dilator  210 ′ clears leading end  104  of cannula  100 , dilator  210 ′ moves into a deployed position. Trailing end  206 ′ of dilator extractor  200 ′ continues moving towards ring  209 ′ until it contacts shoulder  207 ′. Shoulder  207 ′ also acts to limit the depth of insertion of dilator extractor  200 ′ into cannula  100 . Shaft  213 ′ has an attached cone that is pushed through retainer  218 ′ so as to fully deploy the cone when shoulder  207 ′ of knob  222 ′ meets ring  209 ′. Cannula  100  is stationary. The cone is welded to outside of shaft  213 ′. It is understood that any of the embodiments disclosed herein may include a configuration having a shoulder at the trailing end of the dilator extractor and a collar with a retainer attached thereto so that as the body is pushed through the retainer, the shoulder of the trailing end of the dilator extractor contacts the collar and the cone deploys. 
   As shown in  FIG. 8 , trailing end  206  preferably includes first and second seals. The first seal preferably forms a duckbill “V” shaped valve made of a resilient material that forms a seal when no instrument is inserted into lumen  208 . The second seal is preferably formed of a resilient material containing a through hole in its center. The through hole is preferably smaller than the maximum cross sectional dimension of the instrument that the through hole is adapted to receive and forms a seal when the instrument is inserted into lumen  208 . For example, both seals may preferably be configured to permit the passage of grasper  300  therethrough while inhibiting a loss of pressure from within the patient. It is appreciated that more than or less than two seals may be used without departing from the scope of the present invention. 
   As shown in  FIG. 9 , excised tissue  70  is grasped by jaws  310 ,  312  of grasper  300  and pulled inside conical tissue space  214 . Once tissue  70  is inside conical tissue space  214 , the entire assembly (grasper  300 , dilator extractor  200 , trocar cannula  100 , and tissue  70 ) is ready for extraction. 
   In instances where the tissue specimen is larger than the inside diameter of cannula  100 , such as would usually be the case for a gallbladder specimen with a  5  mm cannula for example, dilator  210  will close somewhat under the influence of the upward force of the surgeon until the tissue resilient forces offset the radial forces asserted by the abdominal wall. At this point conical tissue space  214  of dilator extractor  200  will no longer contract and grasper  300 , dilator extractor  200 , and cannula  100  will be locked together in a more or less rigid fashion. This condition is depicted in  FIG. 10 . Dilator extractor  200  is constructed in such a manner that application of additional force causes the wedge shape of dilator  210  to begin to increase or dilate the trocar wound in the abdominal wall as the surgeon applies more and more upward force. The larger the specimen, the larger the force necessary to dilate the abdominal wall wound to a size large enough to allow the entire assembly to be removed. The tensile strength of dilator  210  must be adequate to withstand the extraction force. The shape of the trocar puncture wound is important to insure against tearing of the entry wound. A slit entry wound rather than star-shaped entry wound is preferred. 
   Grasper  300 , as shown in  FIGS. 1 and 8 , has a shaft  302  having a leading end, a trailing end, and a lumen through the center of shaft  302  that can be occupied by a needle of a syringe device. Shaft  302  includes jaws  310 ,  312  at the leading end for grasping tissue therebetween. As will be appreciated by those of skill in the art, grasper  300  may be adapted to have more than two jaws. For example, a third jaw maybe used to provide a third grasping surface for grasping the tissue. It will be further appreciated that other jaw configurations are possible and within the scope of the present invention. Jaws  310 ,  312  may have a smooth grasping surface, or may have ridges. 
   Shaft  302  preferably has a length in the range of 15 cm to 35 cm and an outside maximum cross sectional dimension of less than 5 mm. The lumen of shaft  302  preferably has an inside maximum cross sectional dimension in the range of 1 mm to 4 mm. 
   As shown in  FIG. 8 , the trailing end of grasper  300  includes a pair of handles  320  for moving jaws  310 ,  312  relative to one another. The trailing end also preferably includes first and second seals. The first seal preferably forms a duckbill “V” shaped valve made of a resilient material that forms a seal when no instrument is inserted into the lumen. The second seal is preferably formed of a resilient material containing a through hole in its center. The through hole is preferably smaller than the maximum cross sectional dimension of the instrument that the through hole is adapted to receive and forms a seal when the instrument is inserted into the lumen. For example, both seals may preferably be configured to permit the passage of a needle therethrough while inhibiting a loss of pressure from within the patient. It is appreciated that more than or less than two seals may be used without departing from the scope of the present invention. 
   The trailing end preferably includes a depth-limiting protrusion for limiting the depth of insertion of grasper  300  into the cavity. The depth-limiting protrusion may be formed as a shoulder, or may form a part of handles  320 . 
     FIG. 11  shows an alternate embodiment inner surface  228  of conical section  216  which is equipped with tissue retaining protrusions such as teeth  234 . Preferably, teeth  234  are generally pointed toward trailing end  206  when dilator  210  is in the expanded position so that as dilator  210  closes around the tissue as shown in  FIG. 11 , teeth  234  bite into the tissue, thus supplying the dominance of the counter acting force to the extraction force rather than the friction of the tissue against inner surface  228  of conical section  216 . It will be appreciated by those skilled in the art that teeth  234  may also be included on the surface of shank  250  if so desired. 
   It will be appreciated by those skilled in the art that other forms of tissue retaining protrusions are suitable for gripping the tissue, for example, tabs, ridges, and knurling. Additionally, the tissue retaining protrusions are preferably uniformly spaced around the longitudinal axis of dilator extractor  200  to provide an even distribution of retaining force against the tissue. Alternatively, tissue retaining protrusions may be positioned on only one side if so desired. Tissue retaining protrusions may also be spaced substantially about the entire area of inner surface  228  of conical section  216 . Preferably, the tissue retaining protrusions are adapted to grab the tissue without penetrating it in order to reduce the risk of content spillage from the tissue. 
   Having described the apparatus, methods for its use will now be described. It should be understood that the order disclosed is only preferred and that the steps may be performed in other orders while still being within the scope of the present invention. Additionally, some steps may be repeated as necessary or omitted. 
   A preferred method for preparing the dilator extractor for surgical use includes producing body  202  and dilator  210 . Body  202  and dilator  210  may be of the same material with a different thickness. Shank  250  is then attached to body  202 . Once dilator  210  and body  202  are assembled together, a key is used to engage distal end  260  of shank  250  to wind dilator around the mid-longitudinal axis of dilator extractor  200 . Once dilator  210  is sufficiently wound, for example, in a substantially cylindrical shape, retainer  218  is put onto or wrapped around dilator  210  to retain dilator  210  in an unexpanded position. The key is removed from distal end 
   A preferred method of removing tissue from the abdominal cavity is shown in  FIGS. 8–10 . Cannula  100  is inserted through the abdominal wall and into cavity  60 , which is preferably pressurized. A cannula having a maximum diameter preferably in the range of 3 mm to 5 mm is used in order to make the procedure less invasive. Dilator extractor  200  is inserted into cannula  100  through seal  102  to a position where leading end  211  of dilator  210  extends beyond leading end  104  of cannula  100 . Dilator  210  is expanded to form tissue extraction space  214 . Grasper  300  is inserted into dilator extractor  200  through a pair of seals and through lumen  208 . Shank  250  is bent by the insertion of grasper  300  as shown in  FIG. 8  such that grasper  300  extends generally through the center of conical section  216  of dilator  210 . A portion of grasper  300  interacts with shank  250  to cause shank  250  to move away from the mid-longitudinal axis of dilator extractor  200 . The interaction of grasper  300  with shank  250  may occur while grasper  300  is being inserted through dilator extractor  200  in a direction substantially parallel to the mid-longitudinal axis of dilator extractor  200 . The tissue is grasped by grasper  300  and manipulated into tissue space  214 . If desired, grasper  300  may be locked to dilator extractor  200  to provide more stability. Next, an upward force is exerted on dilator extractor  200 , dilating the trocar wound such that the tissue is removed from the cavity under the influence of the upward force. The upward force also causes conical section  216  to roll-up, creating a generally evenly distributed constricting force upon the captured tissue. The constricting force greatly reduces the risk of the tissue tearing or rupturing at the grasper/tissue interface. 
   Alternately, for tissue containing a fluid such as bile in a gallbladder, additional steps may be included such as suctioning out the fluid prior to the extraction step. For example, a needle of a syringe device is inserted into grasper  300  through the seals and through the lumen to a position where the leading end of the needle extends beyond leading end  204  of body  202  of dilator extractor  200 . Fluid is then suctioned from the tissue through the needle by the syringe. It will be appreciated that vacuum sources other than the syringe may be used to aspirate the tissue, for example, an aspirator. It will be further appreciated that aspiration may occur during other phases of the operation prior to the extraction of the tissue from the wound site. For example, a needle may be inserted through lumen  208  of dilator extractor  200  and fluid suctioned from the tissue before grasper  300  is inserted or used. 
   To further reduce the extraction force needed to withdraw the assembly with the tissue, the tissue may be treated to at least partially dissolve the tissue or its contents, for example, gallstones of a gallbladder. A syringe may be used to inject a composition capable of dissolving tissue. One example of such a composition is methyl tert-butyl ether. The tissue is treated preferably after fluid is suctioned. It will be appreciated that the tissue may be treated irrespective of any fluid suction. 
   Simulated dilator extractors were built and tested in the abdominal cavity of a swine. Aluminum cones of varying base diameters representing varying tissue sizes simulated the dilator section. Abdominal access for the cones was gained through a 100 mm incision along the midline of the animal. A 5 mm trocar with a single sided cutting tip obturator (rather than the more common three side pyramidal tip) was used to entry the cavity through a circular 5 mm wound located approximately 30 mm to the left of the midline. Each of four simulators consisting of 5 mm cylinders, 100 mm long transitioning into truncated cones with 5 mm diameter tops tapering to bases of 15, 20, 25, 30 mm diameters respectively, were separately tested by inserting them through the access incision. The 5 mm trocar was then inserted into the abdominal cavity, the obturator removed, and the 5 mm simulator tops were then inserted from the distal of the cannula so that they were exposed above the cannula valve. A force gage was then attached to the exposed section. The vertical pull force required to dilate the 5 mm puncture wound so that the cone was total extracted from the animal was then measured with a calibrated force gage. A new 5 mm trocar site was used for each of the four cones. The extraction force is shown in the table below: 
   
     
       
             
             
             
           
         
             
                 
                 
             
             
                 
               Cone Base Diameter, mm 
               Upward Extraction Force, lbs 
             
             
                 
                 
             
           
           
             
                 
               15 
               12 
             
             
                 
               20 
               21 
             
             
                 
               25 
               37 
             
             
                 
               30 
               50 
             
             
                 
                 
             
           
        
       
     
   
   Each measurement was repeated using the same puncture wound to test the extent to which the wound had been torn or permanently stretched. The data indicated that dilation of 2 to 3 times is possible. In ranges up to 20–25 mm, the forces are of reasonable magnitude to make the device practical. Minimizing wound size is important to minimizing postoperative hernias and other complications. 
     FIG. 7A  shows a tissue collection bag in accordance with another preferred embodiment of the present invention generally referred to by the number  400 . Bag  400  includes a top  402 , a bottom  404 , a first side  406 , a second side  408  and an interior  410 . First and second sides  406 ,  408  are preferably heat welded together along interface  412 ,  414 . Bag  400  is preferably made of a flexible material such as polyurethane. Top  402  includes a hem  416 . Hem  416  is preferably heat-sealed and configured to receive an expansion member  418  at each juncture of first and second sides  406 ,  408 . 
   Expansion member  418  includes a bend preferably in the form of a torsion coil with an arm  420  at each end of coil  422 . Coil  422  preferably has between one to four turns, though the invention is not so limited. In a deployed position, arms  420  have an included angle therebetween of approximately 120 degrees. As will be appreciated by others of ordinary skill in the art, arms  420  may be biased to open at other angles greater or less than 120 degrees, such as 45 degrees or 90 degrees. Expansion member  418  may also have more than two arms, for example, a third arm depending downwardly towards bottom  404  of bag  400 . The bend and any arms associated therewith may be made of a shape memory material. 
   Preferably an eyelet  424  is formed on the top of expansion member  418 . Eyelet  424  is configured for grasping by an instrument such as grasper  300 . Eyelet  424  preferably has an opening  426  to permit a thread or wire to be inserted therethrough to aid in closing bag  400 . The thread may extend within hem  416  and through eyelet  424 , through only eyelet  424 , or through hem  416  alone. Other features for closing bag  400  may be used, for example, a press-seal such as found on sandwich bags. 
   In use, bag  400  is inserted through a cannula in an undeployed position with a retainer wrapped therearound in a generally cylindrical configuration in a similar fashion to dilator extractor  200 . Once inserted into the cavity of the patient, bag  400  is deployed and expansion arms  420  are released to open top  402  of bag  400 . A grasper is used to manipulate tissue into bag  400 . Once the tissue is inside bag  400 , the eyelets are held by a grasper and the bag extracted from the cavity. Before extracting bag  400  from the cavity, a thread or wire may be inserted through opening  426  of each eyelet and pulled to provide a better seal of top  402 . 
   Bag  400  may be inserted and deployed without any attached link such as a handle or wire remaining outside the cavity. Such a configuration is advantageous when used in combination with a dilator extractor as the dilator extractor may be used to withdraw a relatively large tissue specimen through a small incision with little risk of leakage. Bag  400  may be shaped to have a generally conical cross section when deployed for ease of extraction via dilator extractor  200 . 
   Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. For example only, the guide surface may also be configured to align the dilator cone with the mid-longitudinal axis of the dilator extractor when an instrument is inserted into the dilator extractor. It is intended that the specification and examples be considered as exemplary only.