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 . fig1 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 fig2 - 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 fig2 , and an expanded position , shown in fig8 . 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 . fig2 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 fig3 - 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 . fig3 and 4 show dilator 210 in the expanded position . once dilator 210 of dilator extractor 200 is in the expanded position as depicted in fig8 , grasper 300 , in a preferred embodiment , is inserted through channel or lumen 208 , into tissue space 214 , and into cavity 60 . fig5 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 . fig6 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 fig8 , 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 fig9 , 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 fig1 . 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 fig1 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 fig8 , 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 . fig1 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 fig1 , 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 fig8 - 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 fig8 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 : 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 . fig7 a 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 interfaces 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 .
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 .