Patent Publication Number: US-2019184136-A1

Title: Method for aspiration of bile

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application claims the benefit of and priority to U.S. Provisional Application Ser. No. 62/608,240, filed on Dec. 20, 2017 the entire contents of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     Diseases and disorders of the gallbladder, pancreas, and bile ducts (i.e., pancreaticobiliary system) are associated with significant morbidity, mortality, and impaired quality of life. Obstructions, tumors, injuries, leakages, inflammation, infection, and lesions can occur in these structures, which can eventually lead to conditions such as biliary colic, cholecystitis, choledocholithiasis, cholelithiasis, pancreatitis, pancreatic duct stone formations, and chronic abdominal pain. Diseases of the pancreaticobiliary system may also be associated with nutritional disorders, such as malnutrition, obesity, and high cholesterol. 
     To treat a blockage within the bile duct, a clinician may perform a biliary drainage procedure to restore adequate drainage through the affected duct. A biliary drainage procedure may include endoscopically accessing the bile duct with a catheter that is advanced over a sharpened stylet. Once the bile duct is punctured, the clinician may confirm the location of the catheter by withdrawing the stylet from the catheter and aspirating bile through the catheter. 
     If the clinician determines that the catheter has been incorrectly placed (e.g., not within the bile duct), the clinician may then have to reposition the catheter, reinsert the stylet through the catheter, re-puncture the bile duct with the stylet, and repeat the aspiration procedure. This technique is labor intensive and may lead to increased discomfort and serious medical complications for the patient. 
     SUMMARY 
     The described features generally relate to improved methods, systems, and devices for accessing a body lumen. A system may include an access catheter and a stylet configured to fit within the access catheter. The stylet may be hollow and include a piercing tip that protrudes from the end of the access catheter. The stylet and access catheter may be advanced together to pierce a wall of the body lumen. The piercing tip may be offset from a circumferential outer surface of the stylet. The hollow stylet may facilitate flushing contrast into and aspirating fluid from a body lumen, thereby reducing or eliminating the procedure of withdrawing the stylet from the access catheter each time a flushing or aspiration procedure is performed. 
     Methods and apparatuses are described for accessing a body lumen. A method for accessing a body lumen is described. The method may include advancing an access system adjacent to the body lumen, where the access system comprises an access catheter comprising a lumen extending from a proximal end to a distal end of the access catheter and a plurality of apertures disposed along a distal portion of the access catheter. The access system may also comprise a stylet configured to fit within the lumen of the access catheter, the stylet comprising a lumen extending from a proximal end to a distal end of the stylet and a piercing tip at the distal end of the stylet configured to protrude from the distal end of the access catheter. The method may also include piercing a wall of the body lumen with the piercing tip of the stylet by advancing the stylet and the access catheter together. 
     In some embodiments, the piercing tip is offset from a circumferential outer surface of the stylet. In some embodiments, the method may include aspirating a fluid from the body lumen through the lumen of the stylet. The method may also include flushing a contrast fluid through the lumen of the stylet. Additionally, the stylet may further comprise a plurality of apertures disposed along a distal portion of the stylet, wherein the contrast fluid is flushed through the plurality of apertures of the stylet. 
     In some embodiments, the access system further comprises a delivery handle assembly, an inner hub housing coupled to a proximal portion of the delivery handle assembly, a sheath coupled to a distal portion of the delivery handle assembly and having a lumen in fluid communication with an inner lumen of the delivery handle assembly, and an access catheter subassembly removably disposed within the inner lumen of the delivery handle assembly and the lumen of the sheath. In some embodiments, the access catheter subassembly may comprise a catheter hub configured for insertion into the inner hub housing, wherein the catheter hub is rotatable with respect to the inner hub housing and the access catheter coupled with the catheter hub. 
     In some embodiments, the method may include rotating the catheter hub with respect to the inner hub housing. In some cases, the distal portion of the access catheter may comprise a pre-defined arcuate shape. The method may further comprise straightening the distal portion of the access catheter by advancing the stylet through the distal portion of the access catheter. 
     A system for providing access to a body lumen may include an access catheter comprising a lumen extending from a proximal end to a distal end of the access catheter and a plurality of apertures disposed along a distal portion of the access catheter. The access catheter may also include a stylet configured to fit within the lumen of the access catheter, the stylet comprising a lumen extending from a proximal end to a distal end of the stylet and a piercing tip at the distal end of the stylet. 
     In some embodiments, the piercing tip is offset from a circumferential outer surface of the stylet. In some embodiments, the stylet may include a first bevel forming a first angle with respect to a longitudinal axis of the stylet, a second bevel forming a second angle with respect to the longitudinal axis of the stylet and abutting the first bevel, wherein the first angle is less than the second angle, and a back-cut bevel forming a back-cut angle with respect to a circumferential outer surface of the stylet, wherein the second bevel and the back-cut bevel abut at the piercing tip. 
     In some embodiments, the stylet may include a single bevel abutting a non-circumferential outer surface of the stylet at the piercing tip, wherein a distal portion of the stylet is curved such that a center line of the stylet intersects the piercing tip. In some examples, the stylet may include three bevels forming three equal angles with respect to a longitudinal axis of the stylet and each abutting with each other at the piercing tip. In some cases, a center line of the stylet intersects the piercing tip. The stylet may also include a plurality of apertures disposed along a distal portion of the stylet, wherein the plurality of apertures extend from a circumferential outer surface of the stylet to an inner surface of the lumen of the stylet. 
     In some embodiments, the system for providing access to a body lumen may include a delivery handle assembly, an inner hub housing coupled to a proximal portion of the delivery handle assembly, a sheath coupled to a distal portion of the delivery handle assembly and having a lumen in fluid communication with an inner lumen of the delivery handle assembly, and an access catheter subassembly removably disposed within the inner lumen of the delivery handle assembly and the lumen of the sheath. The access catheter subassembly may comprise a catheter hub configured for insertion into the inner hub housing, wherein the catheter hub is rotatable with respect to the inner hub housing and the access catheter coupled with the catheter hub. 
     In some embodiments, the system for providing access to a body lumen may include a stylet hub coupled with the proximal end of the stylet and configured to removably couple with the catheter hub, wherein the stylet hub comprises a syringe port in fluid communication with the lumen of the stylet. In some examples, a cross-section of the distal end of the stylet and a cross-section of the proximal end of the stylet are circular. In some cases, the distal portion of the access catheter comprises a pre-defined arcuate shape, and wherein the distal portion of the access catheter is configured to straighten from the pre-defined arcuate shape as the stylet is advanced through the distal portion of the access catheter. In some embodiments, a circumferential outer surface of the stylet comprises a lubricous coating. 
     Certain examples of the present disclosure may include some, all, or none of the above advantages or features. One or more other technical advantages or features may be readily apparent to those skilled in the art from the figures, descriptions, and claims included herein. Moreover, while specific advantages or features have been enumerated above, various embodiments may include all, some, or none of the enumerated advantages or features. 
     Further scope of the applicability of the described methods and systems will become apparent from the following detailed description, claims, and drawings. The detailed description and specific examples are given by way of illustration only, since various changes and modifications within the spirit and scope of the description will become apparent to those skilled in the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the appended figures, similar components or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label. 
         FIG. 1  illustrates an exploded view of a system for providing access to a body lumen in accordance with aspects of the present disclosure. 
         FIG. 2  illustrates a perspective view of an access system with a stylet in accordance with aspects of the present disclosure. 
         FIG. 3A  illustrates a perspective view of a stylet with a beveled tip in accordance with aspects of the present disclosure. 
         FIG. 3B  illustrates a side view of the stylet of  FIG. 3A  in accordance with aspects of the present disclosure. 
         FIG. 3C  illustrates a top view of the stylet of  FIG. 3A  in accordance with aspects of the present disclosure. 
         FIG. 4A  illustrates a perspective view of a stylet with a bent tip in accordance with aspects of the present disclosure. 
         FIG. 4B  illustrates a side view of the stylet of  FIG. 4A  in accordance with aspects of the present disclosure. 
         FIG. 4C  illustrates a top view of the stylet of  FIG. 4A  in accordance with aspects of the present disclosure. 
         FIG. 5A  illustrates a perspective view of a stylet with a welded tip in accordance with aspects of the present disclosure. 
         FIG. 5B  illustrates a side view of the stylet of  FIG. 5A  in accordance with aspects of the present disclosure. 
         FIG. 5C  illustrates a top view of the stylet of  FIG. 5A  in accordance with aspects of the present disclosure. 
         FIG. 6A  illustrates a perspective view of an access system in a linear configuration in accordance with aspects of the present disclosure. 
         FIG. 6B  illustrates a perspective view of the access system in a nonlinear configuration in accordance with aspects of the present disclosure. 
         FIG. 7  illustrates a system for accessing a body lumen of the pancreaticobiliary system in accordance with aspects of the present disclosure. 
         FIG. 8  illustrates a system for accessing a body lumen of the pancreaticobiliary system in accordance with aspects of the present disclosure. 
         FIGS. 9-10  illustrate flow diagrams of methods of accessing a body lumen in accordance with aspects of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure is generally directed to apparatuses, systems, and methods for accessing a body lumen and aspirating fluid from the body lumen for subsequent treatment. In accordance with various examples, a system for accessing a body lumen may include an access catheter and a stylet, where the stylet is configured to fit within a lumen of the access catheter and to work in concert with the access catheter to pierce the luminal wall. In some examples, the system also includes a delivery handle member with one or more features configured to manipulate the axial and rotational movement of the access catheter and stylet, with respect to each other and the accessed body lumen. 
     The stylet may be configured to pierce the luminal wall for access into the body lumen. For example, the stylet may include a piercing tip that protrudes from the distal end of the access catheter. The stylet and the access catheter may advance together to pierce the luminal wall of the body lumen. In some examples, the piercing tip is offset from a circumferential surface of the stylet, which may reduce catching of the stylet on the inner wall of the access catheter (or an external sheath) as the stylet is advanced through the access catheter or access system. The circumferential offset may be the result of one or more bevel cuts of the distal tip (e.g., a back cut). In some examples, the circumferential offset is achieved by bending the distal tip toward a center line of the stylet. In yet other examples, the distal tip may be centered on the center line of the stylet. 
     As described with reference to various examples, the stylet may include one or more features designed to flush contrast or aspirate fluid from a body lumen without the removal of the stylet from the access catheter. For example, all or a portion of the stylet may be hollow (e.g., may include a lumen extending from a proximal end to a distal end of the stylet). In some examples, the stylet may include apertures disposed along a portion of the wall of the stylet to further facilitate the aspiration and flushing of fluid through the stylet. The features of the stylet that facilitate aspirating or flushing fluid through the stylet, instead of removing a solid stylet from a catheter to flush or aspirate, may reduce the complexity and risk associated with performing certain luminal access procedures, such as those of the pancreaticobiliary system. For example, in the case of a biliary access procedure, the piercing tip of the stylet may puncture the bile duct, the clinician may aspirate fluid from the bile duct through the stylet and flush contrast through the stylet into the bile duct to confirm proper access location in the bile duct. That is, the location may be confirmed without the removal of the stylet from the lumen of the access catheter. This technique may eliminate the need to reinsert the stylet if the access catheter is positioned adjacent to the wall of the target body lumen. In some cases, penetrating the tissue and confirming the location without removal of the stylet may save the clinician time in performing the procedure and may prevent increased discomfort to the patient. 
     In various examples, the distal section of the access catheter includes a plurality of apertures to increase the flexibility of the distal section. For example, the shape, size, and pattern of the apertures may be tailored to achieve certain access catheter characteristics such as the shape of the distal section in the nonlinear configuration, a certain stiffness of the distal section, a particular flexibility profile, or resistance to fracture. The apertures may be sized and located along the access catheter to facilitate the advancement of the stylet or guide wire without catching on the apertures. For example, the distal tip of the stylet may be offset from a circumferential surface of the stylet to reduce catching on the apertures of the access catheter as the stylet is advanced through the access catheter. Additionally, the stylet may be inserted into the lumen of the access catheter to prevent leakage of fluid and/or contrast through the apertures when the clinician aspirates fluid through the stylet and flushes contrast through the stylet. In some examples, the same or different shaped apertures may be included on a section of the access catheter proximal to the pre-curved distal section in order to provide flexibility along this section to facilitate advancement of the access catheter and stylet deeper into the body lumen. 
     Examples of the present disclosure are now described in detail with reference to the drawings. As used herein, the term “clinician” refers to a doctor, surgeon, nurse, or any other care provider and may include support personnel. The term “proximal” will refer to the portion of the device or component thereof that is closer to the clinician and the term ‘distal” will refer to the portion of the device or component thereof that is farther from the clinician. 
       FIG. 1  illustrates an exploded view of a system  100  for providing access to a body lumen in accordance with aspects of the present disclosure. The system  100  generally includes an access catheter  105 , a stylet  135 , a guidewire  155 , and a delivery handle assembly  170 . The system  100  can be provided as individual components, selectively combined components, or all together as a kit of components. The access catheter  105  may be inserted into the delivery handle assembly  170  (through the proximal end  188 ) until the access catheter hub  125  abuts against the proximal end  188 . Once assembled, the access catheter  105  extends through the delivery handle assembly  170  and through the elongate sheath  180  to the target body lumen. 
     The stylet  135  is generally an elongate, tubular member with proximal end  140 , and distal end  142 , and distal portion  145 , and is dimensioned to fit within and slidably advance through the lumen  110  of the access catheter  105 . The stylet  135  may include a sharpened tip (e.g., a piercing tip) at the distal end  142 . The stylet  135  may also include a stylet hub  150  coupled with the proximal end  140  of the stylet  135  to facilitate longitudinal manipulation of the stylet  135  with respect to the access catheter  105 . In some cases, the stylet hub  150  may be uncoupled from the proximal end  140  of the stylet  135  to facilitate removal of the stylet  135  from the access catheter  105 . 
     The guidewire  155  is generally a flexible elongate member configured to slidably advance through the lumen  110  of the access catheter  105 . The guidewire  155  may be uniform in size and stiffness along its entire length, or alternatively, may include sections of differing stiffness. 
     During a luminal access procedure, the access catheter  105  may access the target lumen by piercing a wall of the lumen, for example. In some examples, the stylet  135  may be used in conjunction with the access catheter  105  to facilitate piercing the luminal wall. For example, the stylet  135  may fit within the access catheter  105  and the piercing tip of the stylet  135  may protrude from the access catheter  105  to pierce tissue. In some cases, the stylet  135  and access catheter  105  may be advanced together to pierce a wall of the body lumen with the piercing tip of the stylet  135 . The sharpened distal tip of the stylet  135  may include a plurality of bevels to form a piercing tip offset from a circumferential outer surface of the stylet  135 . As such, the body of the stylet  135  may advance through the lumen of the access catheter  105  without catching on the inner surface of the access catheter  105  or an external sheath. In addition, all or a portion of the stylet  135  may be hollow so that fluid may be flushed and aspirated through the stylet  135 . A distal portion  145  of the stylet  135  may include apertures disposed along the wall of the stylet  135  to further facilitate in the flushing and aspiration of fluid. 
     Once the access catheter  105  has accessed the lumen, the clinician may aspirate fluid from the lumen (e.g., bile duct) through the stylet  135  and flush contrast through the stylet  135  into the lumen. After the proper access location in the bile duct is confirmed, the clinician may remove stylet  135  from the access catheter  105 . The guidewire  155  may be advanced through the access catheter  105  and into the lumen. After correct placement of the guidewire  155  inside the body lumen, the access catheter  105  may be removed. The guidewire  155  may remain inside the body lumen to allow correct placement of other devices (e.g., a stent). 
     In some examples, a distal section  130  of the access catheter  105  is configured to curl or curve into a pre-defined arcuate shape (e.g., through heat setting techniques). For example, a distal section  130  of the access catheter  105  may include one or more apertures  190  that are sized, arranged, or otherwise configured to facilitate flexing or bending of the distal section  130  to the nonlinear shape. The stylet  135  and access catheter  105  may be configured such that as the stylet  135  is advanced through the curved distal section  130  of the access catheter  105 , the distal section  130  of the access catheter  105  straightens out. This may be achieved by tailoring the relative stiffness of the distal section  130  of the access catheter  105  with respect to the stylet  135 . 
     For example, a distal section  130  of the access catheter  105  may be configured to passively transition (i.e., naturally move in the absence of constraining forces) from a linear shape into a nonlinear shape within a body lumen, and vice versa. For example, in accordance with various examples, the distal section  130  may be constrained in a linear configuration by an internal member (e.g., a stylet  135 ) or an external member (e.g., a elongate sheath  180 ), and as the member is withdrawn (e.g., translated axially with respect to the access catheter  105  in the proximal direction), the distal section  130  may then passively transition into a nonlinear configuration. 
     In accordance with various examples, one or more apertures  190  are disposed along the distal section  130  and are sized, arranged, or otherwise configured to facilitate flexing or bending of the distal section  130  to the nonlinear shape. In some cases, a variety of shapes and patterns of the apertures  190  may be used to impart certain flexibility characteristics to the access catheter  105 . In some examples, the apertures  190  may extend proximal to distal section  130 , thereby providing flexibility to portions of the access catheter  105  that are not configured to passively transition into a nonlinear shape. 
     The delivery handle assembly  170  is generally configured to facilitate manipulation of the access catheter  105 , the stylet  135 , and the guidewire  155  with respect to each other, the accessed body lumen, or an attached endoscope. The delivery handle assembly  170  may include a proximal handle member  172  with a proximal end  188 , a middle handle member  174 , and a distal handle member  176 . The proximal, middle, and distal handle members  172 ,  174 ,  176  each include an inner lumen and are coupled together to form a continuous lumen extending throughout the length of the delivery handle assembly  170 . The proximal handle member  172  is slidably disposed over at least a portion of the middle handle member  174 , and, similarly, the middle handle member  174  is slidably disposed over at least a portion of distal handle member  176 . The distal handle member  176  may also include a threaded connector element  178  configured to securely attach to a working channel of an endoscope (not shown). 
     One or more of the proximal, middle, and distal handle members  172 ,  174 , and  176  of the delivery handle assembly  170  may be configured to manipulate one or more components of a bile aspiration system. For example, a proximal hub may be configured to advance and retract the stylet  135  with respect to the elongate sheath  180 . A middle hub may be configured to advance and retract the sheath itself. As such, the middle hub may facilitate advancement of the elongate sheath  180  and manipulation of the elongate sheath  180  with respect to a body lumen. 
     The delivery handle assembly  170  may also include an elongate sheath  180  extending from the distal end of the distal handle member  176 . The elongate sheath  180  is generally made from a flexible polymeric material and provides a continuous conduit through which the access catheter  105  or other elements (e.g., a stylet  135 ) may travel between the delivery handle assembly  170  and the target tissue within the body (e.g., the bile duct). Accordingly, the length and diameter of the elongate sheath  180  may depend upon the particular application. 
     The delivery handle assembly  170  may also include one or more adjustment features that limit the sliding movement of the proximal, middle, and distal handle members  172 ,  174 ,  176  relative to each other. For instance, the delivery handle assembly  170  may include a locking ring  182  with a threaded thumbscrew  184  disposed around the middle handle member  174 . The locking ring  182  may be slid along the middle handle member  174  and tightened in a desired position with the threaded thumbscrew  184 . When tightened, the locking ring  182  limits the movement of the proximal handle member  172  in the distal direction relative to the middle handle member  174 , thereby allowing the clinician to establish a set penetration depth of the access catheter  105  or stylet  135  beyond the distal end of the elongate sheath  180 . Similarly, a thumbscrew  186  is configured to lock the position of the distal handle member  176  with respect to the middle handle member  174 , thereby allowing the clinician to set an extension depth of the elongate sheath  180  beyond the distal end of an attached endoscope. 
     The system  100  may be used to access and provide treatment to one or more body lumens within the gastrointestinal system or pancreaticobiliary system, for example. It may be appreciated that the system  100  may also be used to provide access or treatment to other organs or luminal systems within the body such as the arterial system, the bronchial system, the urinary system, or any other luminal system were maneuverability and accuracy is desirable. 
     In some examples described herein, the delivery handle assembly  170  is coupled with an endoscope and the access catheter  105  is guided via endoscopic ultrasound (EUS) to provide access to one or more body lumens or organs associated with the pancreaticobiliary system for the purpose of providing treatment. For example, the system  100  may be configured to provide access to at least the common biliary duct to facilitate subsequent procedures to treat narrowed areas or blockages within the bile duct, including palliative drainage procedures. In accordance with various examples, the system  100  may be used to perform an Endoscopic Ultrasound Guided Biliary Drainage (EUS-BD) procedure. In a particular embodiment, a palliative drainage procedure may be performed in antegrade fashion in conjunction with the system  100 . In another embodiment, the palliative drainage procedure may be performed in retrograde fashion, referred to as an Endoscopic Retrograde Cholangiopancreatography (ERCP) “Rendezvous” procedure. 
       FIG. 2  illustrates an example of a stylet  200  in accordance with aspects of the present disclosure. The stylet  200  may be an example of aspects of stylet  135  described with reference to  FIG. 1 . The stylet  200  may be configured to pierce a wall of a body lumen and aspirate fluid from the body lumen or flush contrast into the body lumen. The stylet  200  may generally include a distal end  205  with a lumen  210  extending from a proximal end to the distal end  205  of the stylet  200 . The stylet  200  may further include a distal portion  215  with a piercing tip  220 . 
     The stylet  200  may generally be a tubular structure that is sized to fit within the lumen of an access catheter, as described with reference to  FIG. 1 . In some cases, the cross-section of the distal end  205  of the stylet  200  and the cross-section of the proximal end of the stylet  200  may be circular. The stylet  200  may access the human body through the working channel of the access catheter, for example, as described with reference to  FIG. 1 . 
     As will be appreciated, the distal end  205  of the stylet  200  may be formed from any number of bevels to form the piercing tip  220 . Furthermore, as will be discussed below, the piercing tip  220  of the stylet  200  may be offset from a circumferential outer surface of the stylet  200 . That is, the piercing tip  220  may be biased towards the center line of the stylet  200 . As such, the stylet  200  may be configured to avoid catching on the inner lumen of the access catheter as the stylet is advanced through the body lumen of the access catheter. 
     In some examples, the distal end  205  of the stylet  200  may be sharpened to penetrate the tissue without coring. When accessing a body lumen such as the bile duct, for example, the piercing tip  220  of the stylet  200  may be exposed (e.g., protruding from the distal end of the access catheter). In some cases, the stylet  200  and the access catheter may be advanced together through the wall of the tissue, for example, as described with reference to  FIG. 6 . 
     As will be discussed below, the stylet  200  may further include a lumen  210  that extends from the proximal end to the distal end  205  of the stylet  200 . As such, the stylet  200  may be configured to flush contrast through the lumen  210  without the removal of the stylet  200  from the access catheter. Similarly, the stylet  200  may be configured to aspirate a fluid from the body lumen through the lumen  210  of the stylet  200 . 
     The stylet  200  may be made from any number of materials and combination of materials. In some cases, the circumferential outer surface of the stylet  200  may be coated with a low friction material. For example, the low friction material may be lubricous coating such as parylene. The stylet  200  may comprise a memory shape material to allow the catheter to travel a tortuous path to the tissue site. For example, the memory shape material may be nitinol. 
       FIG. 3A  illustrates a perspective view of an stylet  300  in accordance with aspects of the present disclosure. The stylet  300  may be designed to pierce the tissue and aspirate fluid from the body lumen. The stylet  300  may be an example of a stylet  200  described with reference to  FIG. 2 . In accordance with various examples, the stylet  300  may be used to flush contrast and aspirate fluid without the removal of the stylet  300  from the lumen of the access catheter, as described with reference to  FIGS. 1-2 . As described above, the stylet  300  may be formed from a number of bevels, such as a first bevel  325  and a second bevel  330 . The stylet  300  may further include a distal portion  315  with a piercing tip  320 . 
     In some cases, the stylet  300  may include a piercing tip  320  at the distal end  305  that is offset from the circumferential outer surface of the stylet  300 . The piercing tip  320  may be formed by the first bevel  325 , the second bevel  330 , and a back-cut bevel  335 . The stylet  300  may further include a lumen  310  that may extend from the proximal end to the distal end  305  the stylet  300 . 
       FIG. 3B  illustrates a side view of the stylet  300  of  FIG. 3A  in accordance with aspects of the present disclosure. The stylet  300  may be manufactured by grinding the material of the stylet  300  to form the piercing tip  320 . As described in more detail below, to form the piercing tip  320  of the stylet  300 , the distal end  305  may undergo a series of cuts. 
     In some examples, the distal end  305  of the stylet  300  may include a number of bevels. For example, the first bevel  325  may be formed by a first angle with respect to the longitudinal axis of the stylet  300 . As an example, the first angle may be 12 degrees. The second bevel  330  may be formed by a second angle with respect to the longitudinal axis of the stylet  300 . For example, the second angle may be 20 degrees. In some cases, the piercing tip  320  may include a back-cut bevel  335 . For example, the back-cut bevel  335  may form a back-cut angle with respect to the circumferential outer surface of the stylet  300 . The back-cut angle may be 30 degrees. The second bevel  330  and the back-cut bevel  335  may abut at the piercing tip  320 . In some cases, the back-cut bevel  335  may prevent the stylet  300  from catching along the access catheter as the stylet  300  advances through the lumen of the access catheter. 
       FIG. 3C  illustrates a top view of the stylet  300  in accordance with aspects of the present disclosure. In some cases, the first bevel  325  may include a portion that is processed to reduce the sharpness of the edge created by the first bevel  325  (e.g., a bead blast process). Reducing the sharpness of the edge of the first bevel  325  may help ensure that tissue is not cut and drawn into the lumen  310  of the stylet  300 . 
       FIG. 4A  illustrates a perspective view of an stylet  400  in accordance with aspects of the present disclosure. The stylet  400  may be designed to pierce the tissue and aspirate fluid from the body lumen. The stylet  400  may be an example of a stylet  200  described with reference to  FIG. 2 . In accordance with various examples, the stylet  400  may be used to flush contrast and aspirate fluid without the removal of the stylet  400  from the lumen of the access catheter, as described with reference to  FIGS. 1-2 . As described above, the stylet  400  may be formed from a single bevel  425 . 
     In some cases, the stylet  400  may include a piercing tip  420  at the distal end  405  that is offset from the circumferential outer surface of the stylet  400 . The distal end  405  may be formed by the single bevel  425 . In some cases, the distal portion  415  may curve at portion  430  of the stylet  400 . 
       FIG. 4B  illustrates a side view of the stylet  400  of  FIG. 4A  in accordance with aspects of the present disclosure. The stylet  400  may be manufactured by grinding the material of the stylet  400  to form the piercing tip  420 . As described in more detail below, to form the piercing tip  420  of the stylet  400 , the distal portion  415  may be formed by heat shaping (e.g., bending) the material of the stylet  400 . In some examples, the distal portion  415  of the stylet  400  may be an example of a Huber tip. 
     In some examples, the distal end  405  may include a single bevel  425 . For example, the single bevel  425  may abut a non-circumferential outer surface of the stylet  400  at the piercing tip  420 . In some cases, the distal portion  415  of the stylet  400  may be curved such that a center line of the stylet  400  intersects the piercing tip  420 . The stylet  400  may be formed by heat shaping (e.g., bending) the stylet  400  at the distal portion  415  and then grinding the distal end  405  of the stylet  400 . As such, the piercing tip  420  may be formed and the lumen of the stylet  400  may be exposed. Alternatively, the stylet  400  may be formed by grinding the distal portion  415  of the stylet  400  to form the piercing tip  420  and then heat shaping (e.g., bending) the distal end  405  of the stylet  400 . 
       FIG. 4C  illustrates a top view of the stylet  400  in accordance with aspects of the present disclosure. In some cases, the lumen  410  of the stylet  400  may extend from the proximal end to the distal end  405  the stylet  400 . Therefore, stylet  400  may be used to flush contrast and aspirate fluid through the lumen  410  without the removal of the stylet  400  from the lumen of the access catheter. 
       FIG. 5A  illustrates a perspective view of a stylet  500  in accordance with aspects of the present disclosure. The stylet  500  may be designed to pierce the tissue with the piercing tip  520  and aspirate fluid through one or more apertures  535 . The stylet  500  may be an example of a stylet  200  described with reference to  FIG. 2 . In accordance with various examples, the stylet  500  may be used to flush contrast and aspirate fluid without the removal of the stylet  500  from the lumen of the access catheter, as described with reference to FIGS.  1 - 2 . As described above, the stylet  500  may be formed from a number of bevels, such as a first bevel  525 , a second bevel  530 , and a third bevel (not shown). 
     In some cases, the stylet  500  may include a piercing tip  520  at the distal end  505 . For example, the piercing tip  520  may intersect a center line of the stylet  500 . The stylet  500  may further include one or more apertures  535  disposed along a distal portion  515  of the stylet  500 . The apertures  535  may provide fluid access to the lumen  510  since the material that forms the piercing tip  520  blocks the lumen  510  at the distal end  505  of the stylet  500 . After the tissue is punctured, the stylet  500  may be advanced forward to expose the apertures  535  and aspirate fluid through the lumen  510  of the stylet  500 . That is, the contrast fluid may be flushed through apertures  535  and the fluid from the body lumen may be aspirated through apertures  535 . 
       FIG. 5B  illustrates a side view of the stylet  500  of  FIG. 5A  in accordance with aspects of the present disclosure. The stylet  500  may be manufactured by grinding the material of the stylet  500  to form the piercing tip  520  at the distal end  505 . In some examples, the material that forms the piercing tip  520  may be a different component that is attached to the stylet  500  at the distal end  505 . 
     The piercing tip  520  may be formed by a number of bevels. For example, the three bevels (first bevel  525 , second bevel  530 , and third bevel) may form three angles with respect to the longitudinal axis of the stylet  500 . The first bevel  525 , second bevel (not shown), and third bevel (not shown) may each be at an angle of 15 degrees with respect to the longitudinal axis of the stylet  500 . In some cases, the three bevels abut with each other at the piercing tip  520 . 
     The stylet  500  may further include one or more apertures  535  disposed along the distal portion  515  of the stylet  500 . The apertures  535  be slits or holes and may extend in any pattern along the distal portion  515  of the stylet  500  and/or around the circumference of the stylet  500 . The apertures  535  may be a laser cut to allow fluid to pass into the lumen  510  of the stylet  500 . The apertures  535  may extend from the circumferential outer surface of the stylet  500  to an inner surface of the lumen  510  of the stylet  500 . 
     In some cases, the stylet  500  may include one or more apertures  540 . Apertures  540  may be equally spaced or unequally spaced around the circumference of the stylet  500  and may be used as welding points to weld or otherwise attach the material that forms the piercing tip  520  to the distal end  505  of the stylet  500 . 
       FIG. 5C  illustrates a top view of the stylet  500  in accordance with aspects of the present disclosure. In some cases, the distal end  505  may include a larger diameter than the proximal end of the stylet  500  (not shown). For example, the piercing tip  520  may be configured to pierce the tissue and prevent the distal end  505  of the stylet  500  from bouncing back inside the access catheter. The smaller diameter along the body of the stylet  500  may be configured to allow space for fluid to pass between the circumferential outer surface of the stylet  500  and the inner surface of the access catheter. 
       FIG. 6A  illustrates a perspective view of an access system  600 - a  in a linear configuration in accordance with aspects of the present disclosure. The stylet  135 - a  (shown in phantom lines) may be an example of a stylet described with reference to  FIGS. 1-5 . In accordance with various examples, the access system  600 - a  may be used to flush contrast and aspirate fluid without the removal of the stylet  135 - a  from the lumen of the access catheter  105 - a , as described with reference to  FIGS. 1-5 . 
     The system  600 - a  includes a stylet  135 - a  slidably disposed within the lumen of an access catheter  105 - a . In some cases, the stylet  135 - a  and access catheter  105 - a  may be advanced together to pierce a wall of the body lumen with the piercing tip of the stylet  135 - a . As illustrated in  FIGS. 6A and 6B , the distal section  130 - a  of the access catheter  105 - a  may be configured to passively transition from a linear configuration ( FIG. 6A ) to a nonlinear configuration ( FIG. 6B ) as the stylet  135 - a  is withdrawn in a proximal direction  605  from the distal section  130 - a  of the access catheter  105 - a . As described with reference to  FIG. 1 , this passive transition may be achieved by shape setting the distal section  130 - a  of the access catheter  105 - a  into a pre-defined nonlinear shape such that in the absence of external constraining forces (i.e., upon removal of the stylet  135 - a ), the distal section  130 - a  will transition into the pre-defined nonlinear shape. It may be appreciated that the stiffness of the distal section  130 - a  relative to the stiffness of the stylet  135 - a  may be adjusted such that the distal section  130 - a  conforms to the shape of the stylet  135 - a  (e.g., linear) while the stylet  135 - a  is within the distal section  130 - a . As shown, the distal section  130 - a  may include a plurality of apertures  190 - a  that impart additional flexibility to the distal section  130 - a.    
     In some examples, a clinician may retract the stylet  135 - a  in a proximal direction  605 , thereby causing the distal section  130 - a  of the access catheter  105 - a  to curl up into a pre-defined arcuate shape (e.g., as shown in  FIG. 6B ). In some cases, the distal section  130 - a  of the stylet  135 - a  may need to be straightened back out. As such, the stylet  135 - a  may then be re-advanced distally through the distal section  130 - a . As described above, because the sharpened distal end of the stylet  135 - a  may be offset from an outer circumferential surface of the stylet  135 - a , the stylet  135 - a  may be advanced distally without catching any of the apertures  190 - a , and the procedure of accessing a body lumen may resume. 
     In some cases, the stylet  135 - a  may be used to flush contrast and aspirate fluid without the removal of the stylet  135 - a  from access catheter  105 - a . This configuration and technique may be advantageous over using the access catheter  105 - a  alone to aspirate and flush fluid, because in such a case, fluid (e.g., bile) may leak from a body lumen and into the rest of the body via the apertures  190 - a.    
       FIG. 6B  illustrates a perspective view of an access system  600 - b  in a nonlinear configuration in accordance with aspects of the present disclosure. The stylet  135 - a  (shown in phantom lines) may be an example of a stylet described with reference to  FIGS. 2-5 . In accordance with various examples, the access system  600 - a  may be used to flush contrast and aspirate fluid without the removal of the stylet  135 - a  from the lumen of the access catheter  105 - a , as described with reference to  FIGS. 1-2 . 
     As described herein, access catheter  105 - a  may include a plurality of apertures  190 - a  disposed along a length of the distal section  130 - a . In general, the apertures  190 - a  impart flexibility to the distal section  130 - a , thereby allowing the distal section  130 - a  to transition into a nonlinear shape as described with reference to various examples of the present disclosure. In certain examples, the apertures  190 - a  extend through the entire thickness of the wall of the access catheter  105 - a . Alternatively, some or all of the apertures  190 - a  may only partially penetrate through the wall of the access catheter  105 - a.    
     In accordance with the present disclosure, the size and shape of the apertures  190 - a , the spacing of the apertures  190 - a , and the overall length of the pattern of apertures  190 - a  may be optimized to yield certain characteristics that may be advantageous for luminal access and guide wire placement. For example, the apertures  190 - a  may be uniform in size, shape and spacing, or may be varied as desired to optimize flexibility, radius of curvature, angle of sweep, strength, fatigue resistance, etc. 
     Examples of the present disclosure are now described in the context of a particular Endoscopic Ultrasound Guided Biliary Drainage (EUS-BD) procedure referred to as an Endoscopic Retrograde Cholangiopancreatography (ERCP) “Rendezvous” procedure. With reference to  FIG. 7 , a system  700  for providing access to a body lumen within the pancreaticobiliary system is illustrated in accordance with various examples. The system  700  may be examples of or include functionality of the systems or components described with reference to any of  FIGS. 1-6 . The illustrated portions of the pancreaticobiliary system include the common bile duct  705 , which drains bile from both the cystic duct  735  (which drains from the gallbladder  730 ) and the common hepatic duct  740  (which drains from the liver  745 ) into the duodenum  715 , where the bile mixes and reacts with digesting food. As shown, the common bile duct  705  joins with the pancreatic duct  720  at the ampulla of Vater  710  (shown obstructed) before draining through the major duodenal papilla into the duodenum  715 . 
     Under a “Rendezvous” technique, a clinician may advance an endoscope  725  (e.g., an EUS endoscope) into the lumen of a patient&#39;s duodenum  715  to a position in which the bile ducts may be visualized (e.g., via endosonography). The clinician may then access the common bile duct  705  by advancing an access catheter  105 - a  from a working channel of the endoscope  725 , through the wall of the duodenum  715  (i.e., trans-duodenally), and then through the wall of the common bile duct  705 . As described with reference to  FIG. 1 , the access catheter  105 - a  may pierce the wall of the duodenum  715  and the wall of the common bile duct  705  by exposing the distal end of a stylet  135  (not shown for clarity) from the distal end of the access catheter  105 - a.    
     Once at least the distal section of the access catheter  105 - a  is within the common bile duct  705  (i.e., accessed the bile duct  705 ), the clinician may then maintain the stylet inside the access catheter  105 - a , thereby allowing the clinician to perform a method of aspiration without withdrawing the stylet, as described with reference to  FIG. 1 . 
     To verify that the access catheter  105 - a  is actually within the common bile duct  705 , the clinician may use a syringe or vacuum to aspirate fluid from the body lumen and then verify that the aspirated fluid is bile (or any other confirmatory fluid depending on the target lumen or organ). As described with reference to  FIGS. 1-6 , the clinician may aspirate fluid through the lumen of the stylet. Once proper placement within the common bile duct  705  has been confirmed, the clinician may flush contrast fluid (i.e., fluid visible under fluoroscopy or any other imaging techniques) through the stylet and into the common bile duct  705  to increase the visibility of the biliary lumens and verify proper access catheter insertion of the bile duct  705 . 
     The clinician may then insert a guidewire  155 - a  into the access catheter  105 - a  through the proximal end and advance it distally towards the distal end. The clinician may then manipulate the distal end of the access catheter  105 - a  by rotating the access catheter  105 - a  or by straightening out or curling up the distal section of the access catheter  105 - a . In the case of the described “Rendezvous” procedure, the clinician may rotate the distal section of the access catheter  105 - a  until the distal end of the access catheter  105 - a  is facing generally along the antegrade direction of flow of the common bile duct  705  (i.e., in the direction of bile flow from the gallbladder  730  to the duodenum  715 ). Furthermore, the clinician may adjust the angle of distal portion (i.e., through straightening or curling) of the distal section of the access catheter  105 - a  by advancing a variable stiffness guidewire  155 - a.    
     After the clinician has manipulated the distal section of the access catheter  105 - a  to the desired orientation through rotation or straightening, the guidewire  155 - a  may then be advanced distally from the distal end of the access catheter  105 - a  and through the bile duct  705  and across the ampulla of Vater  710  into the duodenum  715 . In some circumstances, the clinician may advance the access catheter  105 - a  further into the bile duct  705  over the guidewire  155 - a  so that the distal end of the access catheter  105 - a  is closer to the ampulla of Vater  710  or luminal obstruction to be treated to provide additional support for crossing the luminal obstruction. When the guidewire  155 - a  has passed through the ampulla of Vater  710  and well into the duodenum  715 , a “Rendezvous” procedure may be performed, wherein the EUS endoscope  725  and the system  700  are withdrawn from the patient, leaving the guidewire  155 - a  in place. A side-viewing endoscope (e.g., duodenoscope) may then be passed into the duodenum  715  adjacent the EUS-placed guidewire  155 - a . The guidewire  155 - a  within the duodenum  715  is grasped with a snare or forceps and withdrawn through the duodenoscope. Access to the common bile duct  705  is then performed in reverse fashion over the guidewire  155 - a , and a standard ERCP procedure can then be performed (e.g., open blocked ducts, break up or remove gallstones, insert stents, or endoscopic sphincterotomy). It should be noted that EUS-guided biliary access to the common bile duct  705  is not limited to trans-duodenal access, as illustrated in  FIG. 7 . For example, access to the common bile duct  705  may be achieved trans-gastrically, such that the access catheter  105 - a  is advanced through the gastric wall and entry into the biliary system could involve the intrahepatic, extrahepatic, or common bile duct  705 . In some examples, the system  700  may be used to directly treat (e.g., antegrade stent delivery) the common bile duct  705  directly through the access hole in the bile duct  705  without requiring a “Rendezvous” procedure as described above. 
     With reference to  FIG. 8 , the system  800  may be used to directly access the pancreatic duct  720  through the gastric wall. Such a procedure may be advantageous if the treatment site (e.g., obstruction) is located antegrade from where the common bile duct  705  and pancreatic duct  720  join. In addition, the system  800  may be used to directly access the gallbladder  730 , the cystic duct  735 , the common hepatic duct  740 , or any other duct or organ within the pancreaticobiliary system. Moreover, the system  800  may be used to access and treat any other lumen within the body such as those associated with the arterial system, the bronchial system, or the urinary system. 
       FIG. 9  illustrates a flowchart of a method  900  of accessing a body lumen in accordance with aspects of the present disclosure. At block  905 , the method may include advancing an access system adjacent to the body lumen. The access system may be an example of the access system described with reference to  FIGS. 1-6 . For example, as described above, the access system may include an access catheter comprising a lumen extending from a proximal end to a distal end of the access catheter and a plurality of apertures disposed along a distal portion of the access catheter. The access catheter may also comprise a stylet configured to fit within the lumen of the access catheter. 
     At block  910 , the method may include piercing a wall of the body lumen with the piercing tip of the stylet by advancing the stylet and the access catheter together. The piercing tip may be an example of any of the piercing tips described with reference to  FIGS. 2-5 . For example, as described above, the stylet may comprise a lumen extending from a proximal end to a distal end of the stylet and a piercing tip at the distal end of the stylet configured to protrude from the distal end of the access catheter. For example, as described above, the piercing tip may be offset from a circumferential outer surface of the stylet. 
       FIG. 10  illustrates a flowchart of a method  1000  of accessing a body lumen in accordance with aspects of the present disclosure. At block  1005 , the method may include advancing an access system adjacent to the body lumen. The access system may be an example of the access system described with reference to  FIGS. 1-6 . For example, as described above, the access system may include an access catheter comprising a lumen extending from a proximal end to a distal end of the access catheter and a plurality of apertures disposed along a distal portion of the access catheter. The access catheter may also comprise a stylet configured to fit within the lumen of the access catheter. 
     At block  1010 , the method may include piercing a wall of the body lumen with the piercing tip of the stylet by advancing the stylet and the access catheter together. The piercing tip may be an example of any of the piercing tips described with reference to  FIGS. 2-5 . For example, as described above, the stylet may comprise a lumen extending from a proximal end to a distal end of the stylet and a piercing tip at the distal end of the stylet configured to protrude from the distal end of the access catheter. For example, as described above, the piercing tip may be offset from a circumferential outer surface of the stylet. 
     At block  1015 , the method may include aspirating a fluid from the body lumen through the lumen of the stylet. At block  1020 , the method may include flushing a contrast fluid through the lumen of the stylet. 
     It should be noted that these methods describe possible implementation, and that the operations and the steps may be rearranged or otherwise modified such that other implementations are possible. In some examples, aspects from two or more of the methods may be combined. For example, aspects of each of the methods may include steps or aspects of the other methods, or other steps or techniques described herein. 
     The description herein is provided to enable a person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not to be limited to the examples and designs described herein but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein. 
     While several examples of the present disclosure have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means or structures for performing the functions or obtaining the results or one or more of the advantages described herein, and each of such variations or modifications is deemed to be within the scope of the present disclosure. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, or configurations will depend upon the specific application or applications for which the teachings of the present disclosure is/are used. 
     Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific examples of the disclosure described herein. It is, therefore, to be understood that the foregoing examples are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, the disclosure may be practiced otherwise than as specifically described and claimed. The present disclosure is directed to each individual feature, system, article, material, kit, or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, or methods, if such features, systems, articles, materials, kits, or methods are not mutually inconsistent, is included within the scope of the present disclosure. 
     All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, or ordinary meanings of the defined terms. 
     The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.” Also, as used herein, including in the claims, “or” as used in a list of items (for example, a list of items prefaced by a phrase such as “at least one of” or “one or more”) indicates an inclusive list such that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). 
     Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more examples.