Abstract:
Percutaneous access systems, including trocars, for accessing desired locations within a subject&#39;s body through the subject&#39;s skin or other tissues that are configured to minimize incision sizes are disclosed. Such a percutaneous access system includes a cannula and an obturator. The cannula includes a passageway with a tapered section and an expandable section at its distal end. The expandable section may include leaves that are configured to extend radially outward as an elongated instrument that has an outer diameter that exceeds a minimum relaxed inner diameter of the tapered section of the passageway is forced through the tapered section. Methods for using such a percutaneous access system, including medical procedures, are also disclosed.

Description:
TECHNICAL FIELD 
       [0001]    This disclosure relates to percutaneous access systems and, more specifically, to percutaneous access systems, including trocars, with cannulas that are configured to minimize the dimensions of an opening through skin. Additionally, this disclosure relates to methods for using percutaneous access systems. 
       RELATED ART 
       [0002]    Trocars have been employed in the medical field for many years. A trocar typically includes a cannula (a hollow tube), an obturator with a sharpened tip that extends through a channel of the cannula and a seal between the obturator and the cannula. The sharp top of the obturator, when extended from a distal end of the cannula, is configured to form an incision, or opening, through a subject&#39;s skin or other tissues and, thus, to be introduced into a site of interest (e.g., a location through which a laparoscopic procedure is to be performed, etc., such as a cavity, a blood vessel, etc.) within the subject&#39;s body. Once the sharp tip of the obturator and the distal end of the cannula have been positioned at the location of interest, the obturator may be removed from the channel of the cannula and the laparoscopic procedure may then be performed through the cannula. 
         [0003]    The distal end of the cannula of a conventional trocar typically has a fixed outer diameter, which is usually consistent with the outer diameter of a remainder of the cannula. Thus, the size of the incision made by the obturator must accommodate the outer diameter of the cannula. In embodiments where the channel of the cannula must accommodate medical instruments with relatively large outer diameters, a cannula with a larger outer diameter is required and, thus, a relatively large incision must be made through the subject&#39;s skin or other tissues. 
         [0004]    Large incisions are typically undesirable for a number of reasons. For example, larger incisions are typically more unsightly than smaller incisions, take longer to heal than smaller incisions, result in an undesirable amount of scar tissue relative to the amount of scar tissue generated as a subject heals from a smaller incision, and pose a greater risk of infection from the procedure and as the subject heals from the procedure. 
       SUMMARY 
       [0005]    This disclosure, in various aspects, relates to enhancements to existing procedures that involve the use of trocars. In addition, this disclosure relates to “percutaneous access systems,” including trocars, for accessing desired locations within a subject&#39;s body through the subject&#39;s skin with minimal incision sizes. 
         [0006]    In one aspect, a percutaneous access system comprises a trocar with a tapered cannula that includes an expandable section at its distal end. In some embodiments, the cannula may include an elastomeric sheath over a proximal portion of the expandable section. The expandable section may include an external taper from a relatively large outer diameter at a proximal location to a smaller outer diameter at a more distal location, as well as an internal taper (along an internal passageway that extends through the cannula) from a relatively large inner diameter at a proximal location to a smaller inner diameter at a more distal location. Slits (e.g., laser cuts, etc.) along the length of the expandable section at various locations around the circumference of the expandable section may separate the expandable section into a plurality of expandable elements (each of which is also referred to herein as a “leaf”), and may enable expansion of the expandable section. 
         [0007]    In addition to the tapered, expandable cannula, a trocar according to this disclosure includes an obturator. The obturator is configured to be inserted from a proximal side of the cannula into and through the cannula, such that a distal tip of the obturator will extend through and protrude from a distal end of the cannula. A distal tip of the obturator may be configured to pierce the skin and/or other tissues of a subject&#39;s body to provide access to a desired location within the subject&#39;s body. More specifically, the distal tip of the obturator may comprise a sharpened point or a sharpened edge, which may be configured to pierce skin or other tissues of the subject and, thus, to form an incision, or opening, and, optionally, a pathway through the skin and/or one or more other tissues of the subject&#39;s body. In some embodiments, an outer diameter of the obturator may be the same as or slightly smaller than a smallest inner diameter of the cannula, enabling the obturator to be completely introduced into and assembled with the cannula, and to protrude from a distal end of the cannula, without causing the distal end of the cannula to expand. Thus, the obturator may form an incision and the unexpanded, tapered distal end of the cannula may follow the distal tip of the obturator into the incision. Alternatively, the obturator may have an outer diameter that exceeds the smallest inner diameter of the cannula, in which case the obturator may be proximally withdrawn through the cannula to enable the distal end of the cannula to contract as it is advanced distally into the incision. 
         [0008]    The obturator may be removed from the cannula to make way for another elongated instrument, such as a laparoscopic surgical instrument, a guidewire, a sheath, a tube and/or a catheter. An outer diameter of the elongated instrument may be less than the relatively large inner diameter of the cannula but, in some embodiments, greater than the smaller inner diameter of the cannula. As an elongated instrument with an outer diameter that exceeds the smaller inner diameter of the cannula is introduced distally through the internal passageway through the cannula, the elongated instrument will force leaves of the expandable section outward, putting the expandable section into an expanded state, in which both the inner diameter and the outer diameter of the distal portion of the expandable section of the cannula are effectively increased. In some embodiments, the portion of the internal passageway of the cannula that extends through the expandable section may be configured to open gradually as the distal end of the elongated instrument moves therethrough, with the expandable section only opening completely when the distal end of the elongated instrument is coincident with the distal end of the cannula. As the outer diameter of the expandable section increases, an opening through any tissues (e.g., skin, etc.) in which the expandable section is located may be dilated, or enlarged. 
         [0009]    When a portion of the elongated instrument that has forced the leaves of the expandable section of the cannula outward is removed from the expandable section (e.g., withdrawn from the internal passageway in a proximal direction, etc.), the leaves may be free to collapse, enabling the expandable section of the cannula to return to its initial collapsed state. The presence of an elastic sleeve, if any, around the proximal portion of the expandable section may ensure that the leaves return to their initial orientations and, thus, that the expandable section returns to its collapsed state. As the expandable section of the cannula collapses, the opening(s) in tissues through within which the expandable section resides may also constrict, or return to its (their) initial, smaller size(s). 
         [0010]    In another aspect, a percutaneous access system, such as a trocar, may include a cannula with an expandable section, an obturator (e.g., a rigid obturator; a flexible, or bendable, obturator; etc.) insertable into and/or movable through the cannula, an optional elongated instrument (e.g., a wire, a sheath, a tube, a catheter, a laparoscopic surgical instrument, etc.) and a housing for maintaining a relationship between the cannula and the obturator or other elongated instrument. The housing may include a distal hub secured to a proximal end of the cannula, a proximal hub configured to engage a proximal portion of the obturator and/or a location along a length of another elongated instrument (e.g., a wire, a sheath, a tube, a catheter, a laparoscopic surgical instrument, etc.), and a main body to which the distal hub and the proximal hub are secured. The distal hub may be fixedly secured in place relative to a distal side of the main body. In some embodiments, the proximal hub may be rotatably secured in place relative to a proximal side of the main body. More specifically, a retaining ring may be configured to be fixedly secured in place relative to the proximal side of the main body of the housing, while holding the proximal hub in place, and enabling the proximal hub and, thus, the elongated instrument to rotate relative to the main body, the distal hub and the cannula. In some embodiments, the proximal hub may be configured to be grasped between an individual&#39;s thumb and finger (e.g., index finger, etc.) to enable manual manipulation of the elongated instrument. One or both of the retaining ring and the main body may be configured to enable or cause the proximal hub and the elongated instrument to rotate and/or otherwise move relative to the main body in a controlled fashion (e.g., along a helical thread, along a spiral groove, etc.). In some embodiments, the retaining ring and/or the main body may be configured in a manner that enables the proximal hub to lock in one or more positions (e.g., in a proximal position (i.e., with the elongated instrument fully withdrawn (proximally) into the cannula), in one or more intermediate positions, in a distal position (i.e., with the elongated instrument fully extended (distally) from the cannula), etc.). In embodiments where the proximal hub can be locked into a distal position as the distal end of the elongated instrument protrudes from the distal end of the cannula. 
         [0011]    The proximal hub of a percutaneous access system according to this disclosure may include a passage extending through its length. The passage through the proximal hub may be continuous with and, thus, communicate with the internal passageway through the cannula. The passage through the proximal hub may be configured to receive an elongated instrument that may also extend into and/or through the internal passageway through the cannula. In some embodiments, the proximal hub (e.g., the passage therethrough, etc.) may be configured to engage the elongated instrument and, thus, cause the elongated instrument to rotate about its longitudinal axis as the proximal hub is rotated about the longitudinal axes of the housing and/or the cannula. 
         [0012]    An access technique according to this disclosure may include introducing an obturator of a trocar into and through a cannula of the trocar in such a way that a distal end of the obturator, which is configured to cut and/or puncture a subject&#39;s skin, protrudes from (and, thus, beyond) a distal end of the cannula. With a longitudinal position of the obturator fixed relative to a longitudinal position of the cannula, the obturator may be positioned against the subject&#39;s skin at a location that is intended to form an incision, or opening, and provide access to a site of interest, and then forced into and at least partially through the subject&#39;s skin. The obturator and a distal and of the cannula may then be advanced to a desired location within the subject&#39;s body (e.g., a vascular location, a non-vascular location, etc.), creating a path that will provide access to the desired location. Once the desired location has been accessed, the obturator may be withdrawn into the cannula and from the percutaneous access system. Another elongated instrument, such as a laparoscopic surgical instrument, a wire, a sheath, a tube and/or a catheter, may be introduced into and through the internal passageway through the cannula. In embodiments where an outer diameter of the elongated instrument exceeds the smaller inner diameter of the expandable section of the cannula, movement of the elongated instrument distally through the expandable second may cause the expandable section to expand, which may dilate, or stretch, one or more openings in tissues through which the expandable section extends rather than requiring the formation of a larger opening or the use of a more complex conventional dilation system. 
         [0013]    Other aspects, as well as features and advantages of various aspects, of the disclosed subject matter will become apparent to those of ordinary skill in the art through consideration of the ensuing description, the accompanying drawings and the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    In the drawings: 
           [0015]      FIG. 1  is a side view of an embodiment of percutaneous access system according to this disclosure, which percutaneous access system comprises a trocar; 
           [0016]      FIG. 2  is an exploded view showing various elements of the embodiment of percutaneous access system of  FIG. 1 , in which the elongated instrument comprises an obturator that is configured to be assembled with a housing and a cannula of the percutaneous access system; 
           [0017]      FIGS. 3 and 4  provide isometric view of the embodiment of percutaneous access system shown in  FIG. 1 ; 
           [0018]      FIGS. 3A and 4A  provide enlarged view of the sections identified as “A” and “B” of  FIGS. 3 and 4 , respectively; 
           [0019]      FIG. 5  illustrates an embodiment of an internal passageway through an expandable section of a cannula, which includes at least one taper; 
           [0020]      FIGS. 6 and 7  are perspective views of an expandable section of the cannula and an elastic sleeve that surrounds a proximal portion of the expandable section, respectively showing the expandable section in collapsed and expanded states; and 
           [0021]      FIGS. 8A-8C  illustrate an embodiment of percutaneous access system in which the housing and cannula are used in conjunction with an elongated instrument, such as a laparoscopic surgical instrument, a wire, a sheath, a tube or a catheter. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    With reference to  FIGS. 1-4, 3A and 4A , an embodiment of a percutaneous access system  10  according to this disclosure is depicted. The depicted percutaneous access system  10  comprises a trocar, which includes a cannula  20 , a handle  40  and an obturator  50 . The handle  40 , which is secured to the cannula  20 , may include a main body  60 , a distal hub  70  and a proximal hub  80 . The obturator  50  is configured for assembly with the handle  40  and the cannula  20 . 
         [0023]    The cannula  20  may be configured similarly to the micro-taper needle of U.S. Pat. No. 7,803,142, the entire disclosure of which is incorporated herein by this reference. More specifically, the cannula  20  may include a proximal end  22  and a distal end  24 . An expandable section  25  may extend proximally from the distal end  24  of the cannula  20  to an intermediate location along its length. The expandable section  25  may include a plurality of slits  26  ( FIGS. 3, 5 and 6 ) that extend through the thickness of a wall of the cannula  20 , which extend along the length of the expandable section  25  and are spaced apart at different locations around the circumference of the expandable section  25 . The slits  26  may separate the expandable section  25  into a plurality of expandable elements, which are also referred to herein as “leaves”  27 . 
         [0024]    In some embodiments, such as that depicted by  FIGS. 1 and 2 , the expandable section  25  may comprise a tapered portion of the cannula  20 . More specifically, a proximal portion of the cannula  20  may have a constant outer diameter (i.e., it may be straight, or untapered), while the expandable section  25  or a portion thereof is tapered. As illustrated, an outer diameter of the cannula  20  may taper from a relatively large dimension at a proximal side of the taper (e.g. at a proximal side of the expandable section  25 , etc.) to a smaller dimension at a distal side of the taper (e.g., at the distal end  24  of the cannula  20 , etc.). 
         [0025]    As illustrated by  FIG. 5 , an inner diameter of an expandable section  35  of an internal passageway  30 , which resides within a tapered portion (e.g., the expandable section  25 , etc.) of the cannula  20 , may also include one or more tapers. In such an embodiment, as an elongated instrument  100  ( FIGS. 7-8C ) (e.g., a laparoscopic surgical instrument, a wire, a catheter, a tube, a sheath, etc.) with an outer diameter that exceeds the inner diameter of any portion of the expandable section  35  moves distally through the internal passageway  30 , the elongated instrument  100  will force the leaves  27  outward, expanding the expandable section  25 . Expansion of the expandable section  25  includes an effective expansion of the inner diameter of the expandable section  35  of the internal passageway  30  within the expandable section  25  of the cannula  20  and an increase in the outer diameter of the expandable section  25 . 
         [0026]    In some embodiments, tapering of the expandable section  35  of the internal passageway  30  that resides within the expandable section  25  of a cannula  20  may be varied. For example, the expandable section  35  of the internal passageway  30  may include at least one tapered portion and at least one straight portion. As another example the expandable section  35  of the internal passageway  30  may include portions with different tapers. Without limitation,  FIG. 5  illustrates an embodiment in which a proximal taper  36  of the expandable section  35  of an internal passageway  30  is configured to cause the expandable section  25  ( FIGS. 1-4, 3A and 4A ) of the cannula  20  ( FIGS. 1 and 2 ) to expand in such a way that an outer diameter of the distal end  24  ( FIGS. 1 and 2 ) of the cannula  20  increases to a first dimension, while a distal taper  37  (which may comprise an inner diameter that decreases from a proximal side of the distal taper  37  to a distal side of the distal taper  37 ) of the expandable section  35  of the internal passageway  30  may enable the expanded outer diameter of the distal end  24  of the cannula  20  to remain the same while an elongated instrument  100  ( FIGS. 8A-8C ) continues to advance distally through the internal passageway  30 . Of course, other variations in the manner in which the expandable section  35  of the internal passageway  30  through the expandable section  25  of a cannula  20  tapers, as well as variations in the outer diameter of an elongated instrument  100  ( FIGS. 7-8C ) that may be moved through the expandable section  35  of the internal passageway  30 , may enable the expandable section  25  of the cannula  20  to expand and/or collapse in any desired fashion as the elongated instrument  100  moves through the internal passageway  30 , or at least through the expandable section  35  of the internal passageway  30 . 
         [0027]    With returned reference to  FIGS. 1-4, 3A and 4A , a percutaneous access system  10  may include an elastic sleeve  28  that surrounds at least a proximal portion of the expandable section  25  of the cannula  20 . In some embodiments, the elastic sleeve  28  may extend from a location at or adjacent to the proximal end  22  of the cannula  20  to a location somewhat proximal to the distal end  24  of the cannula  20 . Without limitation, a distal end  29  of the elastic sleeve  28  may be located about 1 cm or about a quarter inch (¼ inch) proximal to the distal end  24  of the cannula  20 . 
         [0028]    The elastic sleeve  28  may be formed from a material that will enable it to conform to the shape and dimensions of the portions (e.g., a proximal portion of the expandable section  25 , etc.) of the cannula  20  over which it is positioned. The material of the elastic sleeve  28 , as well as its dimensions (e.g., its thickness, etc.), may enable the elastic sleeve  28  to expand while the expandable section  25  expands, and to contract upon removal of an expansion force (e.g., partial or complete removal of an elongated instrument  50 , etc.) from the expandable section  25 . As the elastic sleeve  28  contracts, it may force the leaves  27  of the expandable section  25  radially inward toward or to their original positions, thereby collapsing the expandable section  25  and, when the expansion force is totally removed therefrom, enabling the expandable section  25  to return to its collapsed state. The material from which the elastic sleeve  28  is formed, along with its dimensions, may also enable it to maintain its integrity when expanded and contracted, without significantly impeding insertion of the cannula  20  into and through a subject&#39;s skin. Suitable materials for use as the elastic sleeve  28  include, but are not limited, to dip molded elastomers and heat shrink elastomers, including elastomeric fluoropolymers. The thickness of the elastic sleeve  28  may be about 0.00025 inch to about 0.0025 inch (e.g., about 0.001 inch, etc.).  FIGS. 6 and 7  respectively show an expandable section  25  of the cannula  20  in collapsed and expanded states. 
         [0029]    As an alternative to the sleeve  28 , or in addition thereto, the expandable section  25  of the cannula  20  may be formed from a material that will resiliently return to its original shape (i.e., that will enable the leaves  27  to collapse) once an expansion force (e.g., an elongated instrument, etc.) is partially or completely removed from the expandable section  25 . 
         [0030]    As illustrated by  FIGS. 2, 3, 3A, 4 and 4A , the obturator  50  of a trocar embodiment of a percutaneous access system  10  according to this disclosure includes a proximal end  52  and a distal end  54 . The distal end  54  may be configured to fit within the internal passageway  30  through the cannula  20  and to be moved, or translated, along a length of the internal passageway  30 , including through the expandable section  35  of the internal passageway  30 . In the depicted embodiment, an outer diameter of a portion of the obturator  50  that resides within and/or is configured to be positioned within at least a portion of the internal passageway  30  through the cannula  20 —i.e., a distal portion of the obturator  50 —is uniform. In the embodiment of percutaneous access system  10  illustrated by  FIGS. 1-4, 3A and 4A , the obturator  50  has an outer diameter that is the same as or slightly less than a smallest inner diameter of the internal passageway  30  through the cannula  20 . Thus, as the obturator  50  is introduced into and through the internal passageway  30 , and as the obturator  50  resides within the internal passageway  30 , the obturator  50  will not cause the expandable section  25  of the cannula  20  to expand, thus enabling the expandable section  25  of the cannula  20  to remain in the collapsed state shown in  FIGS. 5 and 6 . 
         [0031]    A proximal end  52  of the obturator  50  may be configured to engage or to be engaged by a corresponding feature of the handle  40  of the percutaneous access system  10 . Without limitation, the proximal end  52  of the obturator  50  may be configured to engage or to be engaged by the proximal hub  80  of the handle  40  of the percutaneous access system  10 . 
         [0032]    As illustrated by  FIG. 7 , an elongated instrument  100  (e.g., a wire, a sheath, a tube, a catheter, etc.) with an outer diameter that exceeds the minimum inner diameter of the expandable section  35  of the internal passageway  30  through the cannula  20  will cause the expandable section  25  of the cannula  20  to expand. As the outer diameter of such an elongated instrument  100  is greater than the minimum inner diameter of the expandable section  35  of the internal passageway  30 , introducing a distal end  104  of the elongated instrument  100  into the expandable section  35  will force to the leaves  27  of the expandable section  25  of the cannula  20  radially outward, enlarging the inner diameter of the expandable section  35  of the internal passageway  30  and expanding the outer diameter of the expandable section  25  of the cannula  20 , particularly at its distal end  24 . 
         [0033]    Referring again to  FIGS. 1-4 , a further description of the manner in which the cannula  20  and the obturator  50  are assembled with one another, and a description of the manner in which the cannula  20  and the obturator  50  function relative to one another are provided. It should be noted that the teachings provided hereinafter are also applicable to the use of an elongated instrument  100  ( FIGS. 7-8C ) with the cannula  20 , in place of the obturator  50 . 
         [0034]    The handle  40  of the percutaneous access system  10  may include a distal hub  70  at the proximal end  22  of the cannula  20  that may facilitate assembly of the obturator  50  or another elongated instrument  100  ( FIGS. 7-8C ) with the cannula  20 . Specifically, the distal hub  70  may include a channel  76  that, at a distal side  74  of the distal hub  70 , receives the proximal end  22  of the cannula  20 . At a proximal side  72  of the distal hub  70 , the channel  76  may be configured to enable alignment of the distal end  54  of the obturator  50  (or of another elongated instrument  100  ( FIGS. 7-8C )) with the internal passageway  30  through the cannula  20 . 
         [0035]    The proximal side  72  of the distal hub  70  may also be configured to couple the cannula  20  to the main body  60  of the percutaneous access system  10 . In a specific, but non-limiting embodiment, the proximal side  72  of the distal hub  70  may be configured to be received within an aperture  65  at a distal side  64  of the main body  60  of the handle  40 , and may be fixedly coupled to the main body  60  (e.g., mechanically, with a suitable glue or cement, etc.). 
         [0036]    The proximal side  62  of the main body  60  of the handle  40  may be configured to receive or otherwise engage a proximal hub  80  of the handle  40 . More specifically, the distal portion  84  of the proximal hub  80  may be configured for receipt by an enlarged proximal portion of a passage  66  through the main body  60  of the percutaneous access system  10 . With the main body  60  and the proximal hub  80  configured in this manner, when the proximal hub  80  is assembled with the main body  60 , a channel  86  that extends through a length of the proximal hub  80  is aligned with and communicates with the passage  66  through the main body  60  and, thus, with the channel  76  that extends through the distal hub  70  and the internal passageway  30  that extends through the length of the cannula  20 . 
         [0037]    In the depicted embodiment, a retaining ring  69  may be configured to hold a distal-most end of the distal portion  84  of the proximal hub  80  in place within the passage  66  through the main body  60 . 
         [0038]    In some embodiments, features  85  (e.g., one or more spiral protrusions, or threads, etc.) on an outer circumference of the distal portion  84  may cooperate with (e.g., be received by, etc.) cooperating features  67  (e.g., one or more spiral grooves, etc.) on an inner circumference of the passage  66  through the main body. With such an arrangement, the movement of the distal portion  84  of the proximal hub  80  and, thus, the movement of the obturator  50  (or another elongated instrument  100  ( FIGS. 7-8C ) into and out of the distal end  24  of the cannula  20 , may be controlled (e.g., by rotation of the proximal hub  80  relative to the main body  60 , etc.). 
         [0039]    In some embodiments, the distal portion  84  of the proximal hub  80 , the retaining ring  69  and/or the passage  66  through the main body  60  may include one or more features  88 ,  68  that enable the proximal hub  80  to lock (rotationally and axially) in one or more positions (e.g., in a proximal position (i.e., with the obturator  50  or another elongated instrument  100  ( FIGS. 7-8C ) withdrawn (proximally) into the cannula  20 ), in one or more intermediate positions, in a distal position (i.e., with the obturator  50  or another elongated instrument  100  fully extended (distally) from the cannula  20 ), etc.). 
         [0040]    On its proximal side  82 , the proximal hub  80  may include one or more coupling features  83  configured to enable the percutaneous access system  10  to be secured to another apparatus. Without limitation, the coupling features  83  may comprise luer lock elements or other features that will enable the proximal hub  80  to be coupled to and uncoupled from a coupling element  53  with coupling features (not shown) at or near the proximal end  52  of the obturator  50  ( FIG. 2 ), which correspond to the coupling features  83  at the proximal side  82  of the proximal hub  80  and which may fix the obturator  50  in place relative to a remainder of the percutaneous access system  10 . Alternatively, or in addition, the coupling features  83  may enable another apparatus, such as an elongated instrument  100  ( FIGS. 7-8C ), to be secured in place relative to the proximal hub  80 . 
         [0041]    While  FIGS. 1-4, 3A and 4A  illustrate an embodiment of percutaneous access system  10  that includes a conventional, straight obturator  50  of a trocar, a percutaneous access system  10  according to this disclosure may also be adapted for use with a bendable obturator and/or a steerable obturator. 
         [0042]    Turning now to  FIGS. 8A-8C , once a percutaneous access system  10  has been used to access a desired location within a subject&#39;s body (e.g., a blood vessel, a cavity, etc.) and the distal end  24  of the cannula  20  is positioned at a desired location within the subject&#39;s body, the obturator  50  ( FIGS. 2, 3, 3A, 4 and 4A ) may be proximally drawn into the distal end  24  of the cannula  20  and removed (e.g., proximally withdrawn) from the internal passageway  30  through the cannula  20 , from the channel  76  ( FIG. 2 ) through the distal hub  70  of the handle  40 , from the passage  66  ( FIG. 2 ) through the main body  60  of the handle  40  and from the channel  86  ( FIG. 2 ) through the proximal hub  80  of the handle  40 , while the distal end  24  of the cannula  20  remains in place within the body of the subject. Removal of the obturator  50  from the cannula  20  and its handle  40  may make way for an elongated instrument  100 , such as a wire, a sheath, a tube and/or a catheter, which may be used to further enable an elongated medical device (e.g., a catheter, etc.) to perform a medical procedure within the subject&#39;s body or to perform a medical procedure within the subject&#39;s body. 
         [0043]    As illustrated by  FIGS. 8A-8C , a percutaneous access system  10 ′ may include a cannula  20 , its handle  40  and an elongated instrument  100 . With the distal end  24  of the cannula  20  of the percutaneous access system  10 ′ at a desired location within the subject&#39;s body, a distal end  104  of the elongated instrument  100  may be introduced into the handle  40  through a proximal opening of the channel  86  ( FIG. 1 ) that extends through the proximal hub  80 . As the elongated instrument  100  is pushed distally into the handle  40 , the distal end  104  of the elongated instrument  100  may move into and through the passage  66  ( FIG. 1 ) through the main body  60  of the handle  40 , into and through the channel  76  ( FIG. 1 ) through the distal hub  70  of the handle  40  and then into and through the cannula  20 . The distal end  104  of the elongated instrument  100  may then emerge from the distal end  24  of the cannula  20 , at the desired location within the subject&#39;s body. Alternatively, a healthcare provider may distally push the elongated instrument  100  further, until the distal end  104  of the elongated instrument  100  is positioned at or near a targeted location within the subject&#39;s body (e.g., a location where a medical procedure is to take place, etc.). 
         [0044]    Once the distal end  104  of the elongated instrument  100  is at the desired location or the targeted location, a proximal end (not shown) or an intermediate location of the elongated instrument  100  may be secured in place relative to the proximal hub  80  of the handle  40  of the percutaneous access system  10 ′. In some embodiments, the proximal hub  80  of the handle  40  of the percutaneous access system  10 ′ may be manipulated in a manner that causes an engagement feature associated with the proximal hub  80  to engage the elongated instrument  100  at a location along a length of the elongated instrument  100 . In a specific embodiment, the proximal hub  80  may be twisted about its access to cause an engagement feature thereof (e.g., an o-ring, a compressible tube, etc.) to abut and engage an exterior surface of the elongated instrument  100 . 
         [0045]    Alternatively, longer elongated instruments  100 , including elongated instruments  100  that are to be introduced farther into a subject&#39;s body than is possible with the longitudinal movement provided by rotation of the proximal hub  80  relative to the main body  60  of the percutaneous access system  10 ′, may merely be inserted through the channel  86  ( FIG. 2 ) of the proximal hub  80 , through the passage  66  ( FIG. 2 ) through the main body  60 , through the channel  76  of the distal hub  70  and through the internal passageway  30  ( FIG. 2 ) that extends through the length of the cannula  20 , which may enable manual longitudinal movement (e.g., with a healthcare provider&#39;s hand, etc.) of the elongated instrument  50 ′. 
         [0046]      FIG. 8A  shows the distal end  104  of the elongated instrument  100  protruding a relatively short distance beyond the distal end  24  of the cannula  20 .  FIG. 8B  shows the distal end  104  of the elongated instrument  100  positioned a greater distance beyond the distal end of the cannula  20 .  FIG. 8C  provides a close-up view of a bent portion  101  of the elongated instrument  100  shown in  FIG. 8B . 
         [0047]    From the foregoing, various uses of the percutaneous access system  10 ,  10 ′, as disclosed above, should be apparent to those of ordinary skill in the art. In one embodiment of use, with returned reference to  FIGS. 1-4, 3A and 3B , the distal end  54  of the obturator  50  may be inserted into the proximal end of the channel  86  through the proximal hub  80 , through the channel  86 , into and through the passage  66  through the main body  60 , into and through the channel  76  that extends through the distal hub  70  and into and partially through the internal passageway  30  of the cannula  20 . With the obturator  50  positioned in this manner (see  FIGS. 2-4, 3A and 3B ), the coupling element  53  at its proximal end  52  may engage the coupling features  83  on the proximal side  82  of the proximal hub  80  to fix the obturator  50  in place relative to a remainder of the percutaneous access system  10 . With this arrangement, rotation of the proximal hub  80  relative to the main body  60  may enable the distal end  54  of the obturator  50  to be moved distally into and through the expandable section  25  of the cannula  20 , and through the distal end  24  of the cannula  20 , as shown in  FIGS. 2-4, 3A and 4A . With the obturator  50  emerging or protruding from the distal end  24  of the cannula  20 , its distal end  54  may be used to puncture the skin, another organ or other tissue of a subject. The distal end  24  of the cannula  20  may also be inserted into and through the subject&#39;s skin, another organ or other tissue. As the distal end  24  of the cannula  20  remains in place within the subject&#39;s body, in embodiments where the distal end  54  of the obturator  50  has been used to puncture a subject&#39;s skin, another organ or other tissue, the obturator  50  may be proximally retracted (e.g., by rotating the proximal hub  80  in the appropriate direction relative to the main body  60 , etc.) and removed from the cannula  20  and the body  40 . 
         [0048]    With the distal end  24  of the cannula  20  remaining in position within the subject&#39;s body, another elongated instrument  100  ( FIGS. 8A-8C ) may be used with the cannula  20  and its handle  40  for any of a variety of medical procedures, including, but not limited to, procedures that require percutaneous access, such as vascular access procedures, laparoscopic procedures or the aspiration of fluid&#39;s from the subject&#39;s body (e.g., in biliary drainage, nephrostomy, abscess drainage and drainage of other fluids from other locations and/or sources). 
         [0049]    Although the foregoing description sets forth many specifics, these should not be construed as limiting the scope of any of the claims, but merely as providing illustrations of some embodiments and variations of elements or features of the disclosed subject matter. Other embodiments of the disclosed subject matter may be devised which do not depart from the spirit or scope of any of the claims. Features from different embodiments may be employed in combination. Accordingly, the scope of each claim is limited only by its plain language and the legal equivalents thereto.