Patent Publication Number: US-2005137499-A1

Title: Ductal lavage catheter

Description:
FIELD OF THE INVENTION  
      The present invention relates to a medical instrument having at least a portion that is introduced into the body of a mammal in order to perform diagnostic or therapeutic medical procedures. Specifically, aspects of the present invention relate to a catheter for introducing into a breast duct through a ductal orifice.  
     BACKGROUND OF THE INVENTION  
      The breast is a specialized, glandular structure including a system of complicated breast ducts that radiate from the nipple and that are bound together by fairly dense connective tissue. Each of these breast ducts includes an associated ductal orifice on the surface of a nipple through which ductal fluid may be expressed. Each duct includes a series of successive interlobular branches that drain through the main, lactiferous branch, which terminates and exits the breast at the nipple via the associated ductal orifice. Immediately proximate the ductal orifice, each lactiferous duct includes a lactiferous sinus in which ductal fluid may accumulate. A ductal sphincter resides within the lactiferous sinus and prevents ductal fluid from unintentionally exiting the breast duct through its associated ductal orifice.  
      Breast cancer is believed to begin in the lining of these breast ducts. For several decades significant members of the medical community dedicated to studying breast cancer have believed and shown that the cytological analysis of cells retrieved from nipple discharge fluid from within breast ducts may provide valuable information leading to identifying patients at risk for breast cancer. Indeed, Papanicolaou contributed to the genesis of such a possibility of a “Pap” smear for breast cancer by analyzing the cells contained in nipple discharge. More recently, cancer specific markers have been detected in ductal fluid obtained by nipple aspiration. However, the retrieval techniques and instruments used by these members of the medical community did not routinely obtain meaningful ductal fluid samples.  
      In their attempts to retrieve the breast duct fluid sample including ductal epithelial cells, practitioners introduced wash fluids into a breast duct using indwelling hair-like single lumen catheters. After the fluid was introduced into the duct, the fluid introduction catheters were removed. Then, externally applied nipple aspiration techniques or external pressure applied to the breast were used to collect samples of the ductal fluid. However, these techniques required that significant, sometimes painful, pressure be created on the nipple surface or along the sides of the breast to overcome the fluid retaining properties of the ductal sphincter. Also, these techniques did not routinely provide meaningful ductal fluid samples with a sufficient number of ductal epithelial cells for a meaningful cellular analysis. These techniques typically caused the recovery of samples with twenty or fewer ductal epithelial cells. Additionally, these techniques did not provide samples with cell clusters of 10 or more cells. As a result, the obtained fluid samples could not consistently provide an accurate indication of whether or not the duct from which they were retrieved included precancerous or cancerous cells. Consistent, meaningful ductal epithelial cell samples have been provided by the medical instrument disclosed in U.S. Pat. No. 6,413,228 to Hung et al. that is hereby incorporated by reference in its entirety.  
      The human breasts are composed of fatty tissue, fibrous tissue, breast ducts and milk glands. Human breasts are believed to contain from 6 to 8, or more breast ducts. The ductal lavage procedure discussed above, and sampling results may be greatly effective in screening patients for an early warning of breast cancer risk. However, in performing the ductal lavage procedure, a physician may have difficulty inserting the catheter into a breast duct. The breast duct is a complex anatomical pathway to the breast milk glands. The physician must access the breast duct so as not to cause damage to the inner walls of the duct and/or avoid puncturing the duct. However, it is believed the deeper a catheter is inserted into breast duct, the greater the risk of puncturing the breast duct walls. Therefore, a need exists for a ductal access catheter that allows the physician to adjust its flexibility and rigidity so as to adapt the catheter to the ductal geometry and direct the catheter deep into branches of the ductal network.  
      During the ductal access procedure, a catheter is inserted into a duct opening in the nipple that may cause some discomfort to the patient. Thus, improved insertions systems and methods for ductal access are needed.  
     SUMMARY OF THE INVENTION  
      Aspects of the present invention pertain to systems and methods for intraductal access and navigation, including a catheter having different distal tip configurations and an introducer having different lengths. In accordance with one aspect of present invention, a device is disclosed for being introduced and positioned within a breast duct for introducing or removing material within the breast duct, the apparatus comprising a manifold hub comprising a plurality of port openings in fluid communication with an interior of the manifold hub, at least two of the openings being in fluid communication with a pair of elongated channels that extend through a portion of the manifold hub and a catheter extending from the manifold hub, the catheter comprising an elongated internal lumen extending substantially parallel to a longitudinal axis of the catheter, said lumen being in fluid communication with the manifold hub and adapted to slidiably receive a ductal introducer. The introducer may extend at least approximately 0.250, 0.492, or 0.984 inches beyond the distal tip of the catheter. The distal tip of the catheter may have an atraumatic configuration.  
      In yet another aspect of the present invention, a device is disclosed for being introduced and positioned within a breast duct for introducing or removing material within the breast duct, said apparatus comprising a manifold hub comprising a plurality of port openings in fluid communication with an interior of said manifold hub, at least two of said openings being in fluid communication with a pair of elongated channels that extend through a portion of said manifold hub and a catheter extending from the manifold hub and a sheath which extends internally through both the hub and the catheter, comprising an elongated internal lumen extending substantially parallel to a longitudinal axis of said sheath, said lumen being in fluid communication with said manifold hub and adapted to slidiably receive a ductal introducer therein and said sheath extends beyond the distal tip of said catheter. The distal tip of the sheath may extend at least approximately 1.5 mm, 6.0, or 18.5 millimeters beyond the distal tip of the catheter. The distal tip of the catheter may have an atraumatic configuration.  
      In still another aspect of the present invention, a method for obtaining cellular material from a human breast milk duct using a ductal access comprising a manifold hub comprising a plurality of port openings in fluid communication with an interior of the manifold hub, at least two of the openings being in fluid communication with a pair of elongated channels that extend through a portion of the manifold hub and a catheter extending from the manifold hub, the catheter comprising an elongated internal lumen extending substantially parallel to a longitudinal axis of the catheter, said lumen being in fluid communication with the manifold hub and adapted to slideably receive a ductal introducer; including the steps of inserting the introducer into the internal passageway of a breast duct; and advancing the catheter into the breast duct.  
      In still another aspect of the present invention, a method for obtaining cellular material from a human breast milk duct using the device comprising a manifold hub comprising a plurality of port openings in fluid communication with an interior of said manifold hub, at least two of said openings being in fluid communication with a pair of elongated channels that extend through a portion of said manifold hub and a catheter extending from the manifold hub and a sheath which extends internally through both the hub and the catheter, comprising an elongated internal lumen extending substantially parallel to a longitudinal axis of said sheath, said lumen being in fluid communication with said manifold hub and adapted to slideably receive a ductal introducer therein and said sheath extends beyond the distal tip of said catheter; including the steps of inserting the introducer into the internal passageway of a breast duct advancing the sheath into the breast duct and advancing the catheter into the breast duct.  
      The above and other aspects, features and advantages of the present invention will be readily apparent and fully understood from the following detailed description illustrative embodiments in conjunction with the accompanying drawings, which are included by way of example, and not by way of limitation with regard to the claimed invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a schematic representation of a first ductal access device in accordance with one or more aspects of the present invention;  
       FIG. 2  is a perspective view of a catheter in accordance with one or more aspects of the present invention;  
       FIG. 3  is a partial schematic side view of a catheter in accordance with one or more aspects of the present invention;  
       FIG. 4  is a schematic side view of a catheter with a removable tip in accordance with one or more aspects of the present invention;  
       FIG. 5  is a schematic representation of a second ductal access device in accordance with one or more aspects of the present invention  
       FIG. 6  is a sectional view of a catheter shown in  FIG. 5  taken along an central axis to illustrate an interior construction and components in accordance with one or more aspects of the present invention;  
       FIG. 7  is a perspective view of a catheter in accordance with one or more aspects of the present invention;  
       FIG. 8  is a sectional view of a catheter shown in  FIG. 7  taken along an central axis to illustrate an interior construction and components in accordance with one or more aspects of the present invention;  
       FIG. 8A  is a sectional view similar to  FIG. 8  showing an alterative embodiment of a catheter in accordance with one or more aspects of the present invention;  
       FIGS. 9A-9C  are diagrams illustrating a method of accessing a breast duct which a catheter of  FIG. 2 ;  
       FIGS. 10A-10C  are diagrams illustrating a method of accessing a breast duct which a catheter of  FIG. 7 ;  
       FIG. 11  is a table illustrating exemplary parametric values and materials for guide wire and introducers that may be implemented with aspects of the present invention;  
       FIG. 12  is a table illustrating exemplary parametric values and materials for cannula that may be implemented with aspects of the present invention; and  
       FIG. 13  is a partial schematic side view of a catheter in accordance with one or more aspects of the present invention.  
       FIG. 14  is a schematic representation of an alternative ductal access device in accordance with one or more aspects of the present invention.  
       FIG. 15  is a schematic representation of an alternative ductal access device in accordance with one or more aspects of the present invention.  
       FIG. 16  is a schematic representation of an alternative ductal access device in accordance with one or more aspects of the present invention. 
    
    
     DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS  
       FIGS. 1-3  illustrate preferred embodiments of an inventive access device  10  for accessing a body orifice, such as a breast duct. The access device  10  comprises a catheter  12  having a distal end  14  with a centrally disposed single lumen  16  which extends the length of the catheter  12 , and an elongated distal tip portion  17  which extends beyond the distal end  14  a predetermined distance. The center axis  21  of distal tip portion  17  extends substantially parallel to the center axis  19  of single lumen  16  and is disposed within the wall of the catheter. In such an exemplary construction, the distal tip portion  17  is disposed “off-axis” or “off-center” from center axis  19  of lumen  16 . The off-axis construction of distal tip portion  17  advantageously maintains the open inner diameter of the catheter for maximum fluid flow in and out of the breast duct. Further, the off axis configuration allows substantially improved flow because it does not to interfere with the introduction or removal of fluid and collected samples so not to compromise the ability to retrieve a meaningful sample while still being in direction of the catheter and lumen. The elongated configuration of the distal tip portion  17  acts as an effective guide while not interfering with fluid infusion or compromising ductal fluid sample collection. Distal tip portion  17  also provides ease of insertion of catheter  12  in the ductal orifice. In one construction, distal tip portion  17  is flexible in nature so as to allow the catheter to traverse the potentially tortuous and/or angled geometry of the human breast duct. Further, distal tip portion  17  distends the ductal orifice to reduce the associated pain upon insertion of the catheter therein.  
      Catheter  12  has dimensions which permit introduction of the distal end  14  through a ductal orifice and positioning a distal end thereof distal to the ductal sphincter of a human breast. In one construction, the catheter  12  has a maximum outer diameter of approximately 0.039 inches so as to cannulate the ductal orifices of the breast. Nevertheless, other dimensions are possible for the outer diameter (e.g., approximately 0.025 to 0.039 inches). Single lumen  16  with an internal ID of approximately 0.025 inches accesses the breast duct and through which fluid is infused, and from which ductal fluid samples including ductal epithelial cells are collected or drawn up out of the duct. Distal tip portion  17  has dimensions which permit introduction through a ductal orifice so as to lead the catheter  12  into the breast duct. In one exemplary construction, distal tip portion  17  has a smaller diameter than the catheter  12  to allow ease, of insertion into the breast duct. Distal tip portion  17  may have a diameter of approximately 0.010 inches, although other dimensions are possible (e.g., 0.008 to 0.012 inches). In an alternative construction, the distal tip portion  17  may be flexible.  
      Referring to  FIGS. 2 and 3 , the distal tip portion  17  may have a tapered configuration being largest at the distal end  14  of the lumen  16  (i.e., proximal end of distal tip  17 ) extending therefrom to be smallest at the distal end  18 . In use, the taper and flexibility of the distal tip portion  17  guides the catheter for intraductal movement. Shown in  FIG. 3 , the transition between the distal tip portion  17  and catheter  12  includes a beveled surface  23 . This beveled surface  23  provides a smooth transition between distal tip portion  17  of catheter  12 , which makes the catheter  12  easy to introduce into the ductal opening after the insertion of the tip portion  17  into the breast duct. Hence, the distal tip portion  17  may hold the duct opening in position so that the catheter  12  enters with relative ease. As may be appreciated by one of ordinary skill in the art, the beveled surface  23  reduces the stress level on the tissue being penetrated and spread open by the distal end  14  of the catheter  12 . In contrast to traditional catheters, discomfort to the patient is greatly reduced with the access device  10  of the present invention. The edges of the catheter at the distal end and the end  18  of the distal tip  17  may include an atraumatic configuration. In one atraumatic configuration, the edges and end  18  are rounded to reduce friction and eliminate surfaces that could puncture or otherwise injure the duct. Thus, this construction reduces localized trauma to the tissue verses non-atraumatic designs.  
      Referring to  FIG. 1 , a multiport hub  22  is coupled to the proximal end  15  of catheter  12 . In a preferred construction, hub  22  includes transparent material so that the user may visualize the flow to and from the breast duct during a lavage procedure. In another construction, hub  22  has a low profile so as to reduce the torque on the breast nipple after insertion of catheter  12 . This overcomes the excessive generated torque on the breast nipple known to cause obstruction of ductal fluid due to compression of the tissue. Thus, improved collection of ductal cellular material is provided.  
      Hub  22  is attached to a tubing set  25  which comprises an infusion tube  24  from which fluid is infused into lumen  16  through hub  22  and a collection tube  26  from which fluid is collected from lumen  16  via hub  22 . Infusion tube  24  and collection tube  26  are attached to hub  22  in a conventional manner to allow fluid flow. In one construction, infusion tube  24  and collection tube  26  are translucent and have standard luer connections at their distal ends that mate with ports on the hub  22  and receive fluids. The proximal ends of the tubes  24 ,  26  also include standard luer connection that a practitioner or attendant to manage the various ductal fluids using an appropriate syringe with a standard male luer. If desired, tubes  24 ,  26  may be labeled to indicate the inflow and outflow paths, e.g. infusion or collection functions.  
      In a further construction, an optional pinch clamp or other flow control device (not shown) may be disposed on the outflow tube, collection tube  26 . In use, the clamp closes the collection tube  24  to prevent fluid leakage from the tubing during fluid infusion into a cannulated breast duct. In one construction, hub  22  includes an ergonomic handle  27  for the user to grasp during a ductal lavage procedure. It should be recognized that a fluid used in the hub  22  and catheter  12  may be virtually any appropriate fluid for the ductal lavage procedure. Exemplary ductal wash fluids which may be used with hub  22  includes but is not limited to saline, phosphate buffered saline, a nonabsorbable fluid, an isotonic solution, an osmotic solution, a hypotonic solution, and a hypertonic solution. Nevertheless, an appropriate therapeutic fluid may be provided by way of the ductal access devices describes herein. Alternatively, the fluids could include diagnostic or therapeutic fluids carrying diagnostic and/or therapeutic agents.  
      In an alternative construction depicted in  FIGS. 5 and 6 , an inventive ductal access system  100 , includes a catheter  112  having a distal end  114  with a centrally disposed single lumen  116  which extends the length of the catheter  112 . Catheter  112  includes a tubular introducer pathway  120  adapted to slidably receive a ductal introducer  118  therein. Long axis  121  of pathway  120  is offset but substantially parallel to long axis  119  of lumen  116 . For ease of explanation, as used herein the term “introducer” is defined to include guidewires, dilators, stylettes or portion of any of these that may be inserted within a passageway of a catheter and into a ductal orifice. Ductal introducer  118  is provided for ease of varying the length of tip portion  117  so as to improve intraductal travel of the catheter  112  within the breast duct and to reduce risk of puncturing the ductal wall and rupturing the breast duct. By removably inserting the ductal introducer  118  into the axis  121  of pathway  120 , the user is able to choose an introducer having a desired stiffness for the particular patient. Additionally, this enables the practitioner or attendant to change the flexibility and stiffness of the introducer  118 . The stiffness and flexibility may be a function of a material property and/or cross-sectional shape. One example of a material property that relates to flexibility is the modulus of elasticity. In another example, the cross-sectional shape of the introducer  118  may be circular, elliptical, oval or other shapes that provide predetermined stiffness in one or more directions. One of skill in the art would recognize these various shapes relate to a section modulus of the introducer  118 . Therefore, it should be recognized that introducer pathway  120  may be virtually any appropriate cross-sectional shape to meet the cross-sectional shape of the introducer  118 .  
      Ductal introducer  118  includes a distal end  122 , which enters the breast duct. The opposing proximal end  124  of ductal introducer  118  includes a handle  126 . Handle  126  provides ease of operation so that a user may grasp and manipulate the introducer  118  to access and navigate the breast duct anatomy. Ductal access device  100  includes a hub  22 ′ which has similar construction and components as hub  22  shown in  FIG. 1 . In hub  22 ′, the introducer pathway  120  extends through so that the introducer  118  may be inserted. The pathway may be a tube extending through the exterior of the hub  22 ′ or the tube may be located on the outer surface of the hub. An adjustable tip portion  117  of introducer  118  is defined from the distal end  122  of ductal introducer  118  to the distal end portion  114  of catheter  112 . In this configuration, the length of the tip portion  117  is selectively adjustable by the user for accessing and traversing the breast duct. In one aspect, ductal introducer  118  may be embodied as a guide wire, which is easily inserted into pathway  120  and into the breast duct. In one construction shown in  FIG. 6 , the center axis  121  of introducer pathway  120  extends substantially parallel to the center axis  119  of single lumen  116 . As discussed above, in such an exemplary construction, the introducer pathway  120  is disposed “off-axis” or “off-center” from center axis  119  of lumen  116 . Thus, ductal introducer  118  with the off-axis construction of catheter  112  provides similar benefits as the ductal access device  10 .  
      The introducers described herein may be formed of appropriate cross-sectional shapes and various materials for medical use. The shapes and materials enable desired rigidity and flexibility for intraductal movement. Alternative materials for the introducer  118  may include but are not limited to: Stainless Steel Wire; FEP; PTFE; PEEK; and PVDF and PEBAX. Nevertheless, other appropriate materials may be employed. Specific dimensional value introducers are shown in  FIG. 11 , but are provided by way of example. Alternate coatings for the introducer and/or catheter may include but are not limited to: hydromer coating; STS SLIP-COAT; MDX; silicone dry; silicone lubricant; PTFE coatings. The specific thickness of the coatings and application may be readily determined by one of ordinary skill in the art.  
      The introducer may be made of metal or plastics and may have a tapered and/or an atraumatic tip for gently probing and accessing a breast duct. In one example, the introducer may be constructed of a superelastic or shape memory material. As used herein, the term “superelastic shape memory material” refers to a class of metal alloys that have a stress-induced phase change or temperate from austenite to martensite and upon stress release, the material springs back to this original phase and shape. The material structure of a superelastic shape memory material regarding austenite and martensite is well known to one of ordinary skill in the metallurgy art. A NiTi material or NiTi alloy may be used as an alloy material for the introducer. As used herein, a NiTi superelastic shape memory material refers to an alloy that is an intermetallic compound of nickel and titanium having nearly equal mixtures as measured by weight. One composition of a NiTi superelastic shape memory material generally has a greater percentage of nickel by weight than titanium, such as 51%-56% of nickel, and preferably 54-55% nickel. The specific percentages of nickel and titanium may be adjusted by one of ordinary skill in the art.  
      It is not necessary for the introducer to be composed The introducer may also be formed of a stiff material such as a metal wire or a flexible material such as plastic. In an embodiment of the invention, the combined introducer may be formed of Nitinol due to its flexibility, durability, and biocompatibility. In an alternative embodiment, the introducer may be formed of multiple materials or the same materials having different stiffnesses. As a result, the introducer may have sections that are more flexible than adjacent sections of the same introducer. As a result, for example, the introducer may have a first, stiff portion for guiding the introducer within the ductal lumen and a second, flexible portion that allows the introducer to conform to the shape of the ductal lumen or lumen branch into which it is introduced. In any of the above-discussed embodiments, the introducer may be coated with a liquid or dry lubricant material that reduces the friction between the introducer and the breast duct during the introduction and advancement of the introducer in the duct.  
       FIGS. 7 and 8  illustrate an alternative construction of an inventive catheter body  212  having a distal end  214  with a centrally (about axis  219 ) disposed single lumen  216  that traverses the length of the catheter body. In an off-axis configuration, an elongated flexible tip  217  extends beyond the distal end  214  along axis  221 . The tip  217  is configured to receive a removable introducer  218 . This feature is achieved in that the tip  217  and catheter body  212  include an internal passageway  220  adapted to slidably receive the introducer  218 . The passageway  220  may be tubular at the tip  217  and is located in the walls of catheter body  212 . Passageway  220  has a closed distal end  122 , which is in the initial portion that enters the breast duct. The passageway  220  is opened at the proximal end  211 . The closed end feature enables the practitioner or user to adjust the flexibility of the distal  217  during cannulation of the breast duct but prevent fluid from entering the passageway  220 . Further, the closed end feature allows the introducer  218  to be removed and another introducer inserted therein when the catheter  212  is positioned within the breast duct. Thus, introducer  218  may be removed or inserted into the tip  217  to selectively adjust the flexibility of tip  217 . This allows the user to insert the introducer  218  making the flexible tip more rigid for insertion into the duct, or remove the stylette making the tip more flexible so the tip may transverse tortuous ductal geometry. In this configuration, passageway  220  extends the length of the lumen  216  and is parallel thereto. Advantageously, an aspect of the present invention provides an option to change to tip flexibility which greatly aids the cannulation of the breast duct. The material and thickness of flexible tip  217  may be chosen to achieve a desired stiffness in combination with the flexure characteristics of introducer  218 . The closed distal end  222  is rounded to reduce friction between the ductal tissue and tip  217  and prevent the distal end  222  from puncturing duct.  
       FIG. 8A  illustrates an alternative catheter body  312 , which has similar construction as catheter body  212  except that a passageway  320  is in the distal tip  317  and not in the walls of the catheter body  312 . This allows the user to insert the introducer  218  through the lumen  316  and into the proximal end  311  of the passageway  320 . Flexible elongated distal tip  317  includes a closed distal end  322  extending to the distal end  314  of catheter body  312 .  
      In the example of the embodiments shown  FIGS. 8 and 8 A, the catheter  212 ,  312  may be provided with a plurality of introducers each of which have a different stiffness characteristic or property. Introducers are provided depending on the portion of duct being accessed. One introducer may be used to introduce the distal tip  217 ,  317  past the ductal sphincter. Another introducer may be provided to enter a desired branch of breast duct. Yet another introducer, if desired, may be used to enter a final portion of branch. This allows practitioner to design stiffness of tip  217 ,  317  to match needs presented by different portions of the duct.  
      An introducer may be designated with a stiffness value to provide certain a stiffness property relative to the other introducers. Purely by way of example, a practitioner may be provided with an introducer having a stiffness value of two, which is designed to be rigid so as to allow penetrating the ductal opening. Another introducer may be provided having a stiffness value four which would be less stiff than a value of two. Yet another introducer may have a value of eight, which would be less stiff than a value of four. In this example, a practitioner is enabled to access the breast duct with a rigid introducer inserted within the passageway  220 ,  320 . The practitioner, while the catheter  212 ,  312  resides within the breast duct, may remove the rigid introducer and an insert another introducer to continue to advance within the breast duct. Thus, the practitioner is allowed to enter the breast with the catheters  212 ,  312  without removing the catheter once the breast duct is accessed. Advantageously, catheters  212 ,  312  allow the practitioner to be more efficient in the ductal access procedure because steps are eliminated or substantially reduced over conventional procedures, e.g., the use of dilators be significantly reduced. Further, patient comfort is increased because less traumatic movement is provided to the breast.  
      In another construction shown in  FIG. 4 , a catheter  412  has a distal end  414  with a single lumen  416  disposed about a central axis  419 , which extends the length of the catheter, and an elongated distal, tip portion  417 , which extends beyond the distal end  414 . Catheter  412  has a bevel face and the tip portion  417  includes an extensible introducer  418  formed as a stylette portion. Stylette portion  418  comprises a distal end  422  extending from a distal opening  423  of a transition portion  425  of the lumen  416 . Transition portion  425  includes a passageway configured to receive a stylette so that the distal end  422  exits the opening  433 . The stylette portion  418  may be made of a flexible metal, plastic material or other materials described above. The stylette portion  418  may be fixed in position and serve as a flexible tip, or it may be removed after insertion of the catheter into the duct. The stylette portion  418  may be removed and replaced with a shorter stylette portion so as to shorten the tip length. Alternatively, the stylette portion  418  may have a longer length. In this manner, the tip length may be adjusted to accommodate the particular duct geometry.  
       FIG. 13  illustrates an alternative construction of an inventive catheter body  512  having a distal end  514  with a centrally (about axis  519 ) disposed single lumen  516  that traverses the length of the catheter body. In an off-axis configuration, an elongated tip  517  extends beyond the distal end  514  along axis  521 . The elongated tip  517  may have a multi-flexion configuration that has separate regions of different flexions that each correspond to the flexibility, or lack thereof, needed to access a respective portion of a breast duct. This multi-flexion zone configuration provides adaptability for a practitioner to reduce steps for accessing a breast and/or customize the access of the duct to increase patient comfort. In one exemplary example, the elongated tip  517  may have three flex zones to accommodate to access a breast duct. A first flexion zone  540  may extend from the distal end to a first intermediate position  542  along the length of the elongated tip. The first flexion zone  540  may be substantially rigid for entering into the breast duct to overcome the resistance force provided by the tissue at the ductal opening. An adjacent second flexion zone  544  may extend to another intermediate position away from first intermediate position  542  along the length of the elongated tip  517 . The second flexion zone  544  may be less rigid than a first flex zone  544  so as to allow the elongated tip  517  to traverse the breast duct geometry. A third flex zone  548  may be provided adjacent to the second flexion zone  544 . The third flexion zone  548  may be more flexible than the second flexion zone. In a specific example, the dimensions of the first flexion zone may be 3 cm from the distal end; second flexion zone may have a length of 4 to 8 cm; and the third flexion own may have a length of 2 to 3 cm. Nevertheless, the length of the zones may be configured as desired by the practitioner.  
       FIGS. 9A-9C  are schematic diagrams illustrating a method of accessing a breast duct by way of a catheter  12  of  FIG. 2 . Referring to  FIG. 9A , the catheter  12  is prepared to be introduced into a ductal orifice so that a distal end thereof will be positioned within the duct beyond the ductal sphincter during ductal lavage, introduction of diagnostic materials and/or introduction of therapeutic materials. As shown in  FIG. 9B , the distal end  14  of the catheter is outside of the duct. The catheter has a flexible distal tip  17 , which provides ease of insertion of catheter  12  in the ductal orifice. Further, the flexible distal tip  17  is inserted into the duct so as to follow the intraductal geometry but not cause damage to the duct. As shown in  FIG. 9C , the distal end  14  has entered the duct. The distal tip  17  continues to follow the intraductal geometry to guide the catheter  12  therethrough. Further, the catheter  12  is more rigid than the distal tip  17  so as to straighten the duct for infusion and collection. Although catheter  12  is described with reference to  FIGS. 9A-9C , other catheters  112 ,  212 ,  312 ,  412 , and  512  may be used in a similar fashion.  
       FIGS. 10A-10C  are schematic diagrams illustrating a method of accessing a breast duct with a catheter body  212  of  FIG. 7 . Referring to  FIG. 10A , the catheter body  212  is prepared to be introduced into a ductal orifice. The practitioner may choose an introducer  218  of a desired flexibility or rigidity. For example, the introducer  218  of different rigidity properties may be inserted for adjusting to a desired tip characteristic during insertion of the distal tip  217  into the breast duct. This arrangement creates a composite insertion member for accessing the breast duct. The desired tip characteristic may relate to the stiffness and flexibility, which may be functions of a material property or a cross-sectional shape. One of skill in the art would recognize that the composite insertion member may have various shapes and material properties to vary the section modulus.  
      In particular, the tip  217  may be selectively made rigid to penetrate the duct orifice. In this configuration, the length of the catheter  212  and distal tip  217  is relatively rigid. In  FIG. 10B , the introducer  218 , which is rigid or somewhat rigid, has been removed from the distal tip  217  while the catheter  212  is inserted in the duct. In this removed configuration, the catheter  212  may flex and bend through the intraductal geometry. If desired, an introducer  218 , which is less stiff, may be inserted into the distal tip  217 . With or without an introducer  218 , the catheter  212  is advanced further into the duct. In  FIG. 10C , once a desired position is reached within the duct, a rigid or somewhat rigid introducer  218  may be inserted and advanced into the catheter  212  to straighten the duct for infusion and collection. In a shape memory embodiment, the stiffness or flexibility of introducer  218  may be adjusted in response to the addition of stimulus or removal of a stimulus without removal from the catheter  212 . While not shown, it should be recognized that distal tip  217  could be inserted into the ductal orifice without the need of an introducer  218 . The introducer of an appropriate stiffness may be inserted into the distal tip  217  during or after intraductal entry of the catheter  212 . Although catheter  212  is described with reference to  FIGS. 10A-10C , other catheters  112 ,  312 ,  412  and  512  may be used in a similar fashion.  
      As illustrated in  FIGS. 5 and 6 , the catheter  112  may be tapered along its length to make a smooth transition with a received introducer  118  so that a perceptible transition between the catheter  112  and the introducer  118  that would cause any pain to the patient is not formed and felt by the patient. The catheter  112  may also include an atraumatic distal tip portion  114  at its distal end. The distal tip portion  114  may be tapered, contoured and/or rounded so as to produce an atraumatic tip that will reduce or eliminate trauma to the duct upon entry through the ductal orifice and introduction into the ductal lumen past the ductal sphincter. The distal tip portion  114  may also reduce or eliminate trauma upon withdrawal of the catheter  112  from the duct after the medical procedure, such as ductal lavage or the infusion of a diagnostic and/or treatment agent, has been completed. The tip portion  114  may be composed of a soft polymeric material, e.g. including polyvinyl chloride, polyethers, polyamides, polyethylenes, polyurethanes, copolymers thereof and the like. The tip portion  114  may have a diameter in the range from about 0.012 inches (about 0.031 mm) to about 0.020 inches (about 0.051 mm). In an embodiment, the tip portion  114  has a diameter in the range from about 0.014 inches (about 0.036 mm) to about 0.018 inches (about 0.046 mm). The length of the tip portion  114  (extending from the distal end of the distal portion of the catheter toward the proximal end of the catheter) may be in a range from about 0.10 inch (about 0.25 cm) to about 1.0 inch (about 2.5 cm), more typically in the range from about 0.20 inch (about 0.50 cm) to about 0.70 inch (about 1.8 cm).  
       FIGS. 14A, 14B , and  14 C depict three different formats of the distal end of an introducer  618 . Referring to  FIG. 14A , a preferred embodiment of the device is shown in a catheter  612  comprising an elongated internal lumen extending substantially parallel to a longitudinal axis of the catheter and adapted to slidably receive a ductal introducer  618 . The distal tip portion  614  of the catheter  612  may be contoured and/or rounded so as to produce an atraumatic tip to form an opening through which the ductal introducer  618  may pass. Such a contour will reduce or eliminate trauma to the duct upon entry through the ductal orifice and introduction into the ductal lumen past the ductal sphincter. The distal tip portion  614  may also reduce or eliminate trauma upon withdrawal of the catheter  612  from the duct after the medical procedure, such as ductal lavage or the infusion of a diagnostic and/or treatment agent, has been completed. The tip portion  614  may be composed of a soft polymeric material, e.g. including polyvinyl chloride, polyethers, polyamides, polyethylenes, polyurethanes, copolymers thereof and the like. The ductal introducer  618  which passes through the internal lumen of the catheter  612 , may extend past the distal tip of the catheter  612  and is of sufficient length such that it may penetrate through the ductal orifice and into the ductal lumen past the ductal sphincter prior to the distal tip of the catheter  614  passes through the ductal orifice. The extended length of the probe introducer  618  provides ease of use as well as increasing patient comfort during the ductal lavage procedure. The extended probe introducer  618  may be used to identify the ductal path as well as to introduce the catheter  612  into the ductal orifice. Previously, the ductal lavage process used a separate device (dilator) to identify the ductal path prior to the insertion of the catheter. The extra device and extra procedural step resulted in additional cost, time, as well as an increase in patient anxiety or discomfort due to an additional insertion step to relocate the ductal orifice and ductal path. The increased length of the probe introducer allows the practitioner to locate the ductal path prior to catheter insertion. The catheter may then be inserted into the ductal path by slipping it over the probe introducer without withdrawing the introducer. In an embodiment of the present invention, the length of the ductal introducer that extends beyond the distal tip of the catheter shown in  FIG. 14A  is at least 0.025 inches.  
      In  FIG. 14B , the introducer  618  extends beyond the distal tip of the catheter  614  at least 0.0492 inches.  
      In  FIG. 14C , the introducer  618  extends beyond the distal tip of the catheter  614  at least 0.0984 inches.  
       FIGS. 15A, 15B , and  15 C depict three different formats of the distal end of a catheter  712 . Referring to  FIG. 15A , a preferred embodiment of the device is shown in a catheter  712  comprising an elongated internal lumen extending substantially parallel to a longitudinal axis of the catheter and adapted to slidably receive a ductal introducer  718 . The distal tip portion  714  of the catheter  712  may be contoured and/or rounded so as to produce an atraumatic tip to form an opening through which the ductal introducer  718  may pass. Such a contour will reduce or eliminate trauma to the duct upon entry through the ductal orifice and introduction into the ductal lumen past the ductal sphincter. The present invention also provides a step transition from the distal tip portion  714  of the catheter to a probe introducer sheath  701 . The distal tip portion of the sheath  701  may be contoured and/or rounded so as to produce an atraumatic tip to form an opening through which the ductal introducer  718  may pass. Such a contour will reduce or eliminate trauma to the duct upon entry through the ductal orifice and introduction into the ductal lumen past the ductal sphincter. The distal tip portion may also reduce or eliminate trauma upon withdrawal of the catheter  712  from the duct after the medical procedure, such as ductal lavage or the infusion of a diagnostic and/or treatment agent, has been completed. The tip portion may be composed of a soft polymeric material, e.g. including polyvinyl chloride, polyethers, polyamides, polyethylenes, polyurethanes, copolymers thereof and the like. The ductal introducer  718  that passes through the internal lumen of the catheter  712  and the sheath  701 , may extend past the distal tip of the sheath and is of sufficient length such that it may penetrate through the ductal orifice and into the ductal lumen past the ductal sphincter prior to the distal tip of the sheath passes through the ductal orifice. The length of the ductal introducer that extends beyond the distal tip of the sheath shown in  FIG. 15A  is at least 6.5 millimeters.  
      In  FIG. 15B , the introducer  718  extends beyond the distal tip of the sheath  701  at least 12.5 millimeters.  
      In  FIG. 15C , the introducer  718  extends beyond the distal tip of the sheath  701  at least 25.5 millimeters.  
       FIGS. 16A, 16B , and  16 C depict three different formats of the distal end of a catheter  812 . Referring to  FIG. 16A , a preferred embodiment of the device is shown in a catheter  812  comprising an elongated internal lumen extending substantially parallel to a longitudinal axis of the catheter and adapted to slidably receive a ductal introducer  818 . The distal tip portion  814  of the catheter  812  may be contoured and/or rounded so as to produce an atraumatic tip to form an opening through which the ductal introducer  818  may pass. Such a contour will reduce or eliminate trauma to the duct upon entry through the ductal orifice and introduction into the ductal lumen past the ductal sphincter. The present invention also provides a step transition from the distal tip portion  814  of the catheter to a probe introducer sheath  801 . The distal tip portion of the sheath  801  may be contoured and/or rounded so as to produce an atraumatic tip to form an opening through which the ductal introducer  818  may pass. Such a contour will reduce or eliminate trauma to the duct upon entry through the ductal orifice and introduction into the ductal lumen past the ductal sphincter. The distal tip portion may also reduce or eliminate trauma upon withdrawal of the catheter  812  from the duct after the medical procedure, such as ductal lavage or the infusion of a diagnostic and/or treatment agent, has been completed. The tip portion may be composed of a soft polymeric material, e.g. including polyvinyl chloride, polyethers, polyamides, polyethylenes, polyurethanes, copolymers thereof and the like. The probe introducer  801  sheath may extend beyond the distal end of the catheter  812 . The extended probe introducer sheath facilitates a smooth transition and entry of the catheter  812  into the ductal orifice. The length of the probe introducer sheath  801  that extends beyond the distal tip of the catheter  812  shown in  FIG. 16A  is at least 1.5 millimeters.  
      In  FIG. 16B , the probe introducer sheath  801  extends beyond the distal tip of the catheter  812  at least 6.0 millimeters.  
      In  FIG. 16C , the probe introducer sheath  801  extends beyond the distal tip of the catheter  812  at least 18.5 millimeters.  
      In another embodiment, the probe introducer sheath  801  and the introducer  818 , may be combined into a single unit (not shown). The combined sheath/introducer may be formed of a stiff material such as a metal wire or a flexible material such as plastic. In an embodiment of the invention, the combined sheath/introducer may be formed of Nitinol due to its flexibility, durability, and biocompatibility. The combined sheath/introducer may be constructed from a Nitinol wire that is ground to include a tapered small diameter tip. In an alternative embodiment, the combined sheath/introducer may be formed of multiple materials or the same materials having different stiffnesses. As a result, the combined sheath/introducer may have sections that are more flexible than adjacent sections of the same combined sheath/introducer. As a result, for example, the combined sheath/introducer may have a first, stiff portion for guiding the combined sheath/introducer within the ductal lumen and a second, flexible portion that allows the combined sheath/introducer to conform to the shape of the ductal lumen or lumen branch into which it is introduced. In any of the above-discussed embodiments, the combined sheath/introducer may be coated with a liquid or dry lubricant material that reduces the friction between the combined sheath/introducer and the breast duct during the introduction and advancement of the combined sheath/introducer in the duct.  
      The combined sheath/introducer may be made of metal or plastics, including shape memory metals and plastics, and may have a tapered and/or an atraumatic tip for gently probing and accessing a breast duct. Preferably, a tapered tip will extend distally of the catheter during the introduction of the catheter into the breast duct. After access of the duct is complete, the catheter may be slipped over the combined sheath/introducer and positioned at a location distal to the ductal sphincter.  
      The catheters as described herein may be constructed of a wide range of appropriate materials for medical use. In a preferred construction, the catheter is formed with PTFE and coated with STS Slipcoat to reduce friction on the device during placement in the breast duct. In lieu of PTFE, alternate materials for the catheter may include but are not limited to: polycarbonate; stainless steel (300 Series); polymide; FEP; PEEK; polyethylene; and PEBAX. Specific dimensional values of catheters are shown in  FIG. 12 , but are provided by way of example. Nevertheless, other appropriate materials and dimensional values may be employed.  
      The hub  22  housing may be molded from a polycarbonate. The tubing set  25  may be made of PVC with luer connectors made of polycarbonate. The tubing set may be made of a variety of conventional materials including but not limited to: silicone; low-density polyethylene; PVC; tygon; or polypropylene.  
      In one manufacturing process, the catheters according to one or more aspects of the present invention may be constructed by using an extrusion process. After the process, the distal end of catheter is shaped by molding and/or cutting. An optional, bevel may be is cut to provide the transition between the distal tip portion and the catheter. The edges of the catheter may be rounded using an RF tipping process known to one of ordinary skill in the art. The catheter may be bonded to the hub using a desired medical grade UV adhesive. In turn, the tubes may be bonded to the hub and to the luer connector using UV adhesive as well. If desired, a pinch clamp may be placed on the outflow tube.  
      The present invention provides a method for obtaining cellular material from a human breast milk duct includes introducing a ductal access device such as devices  12 ,  112 ,  212 ,  312 ,  412 , and  512  having at least one lumen into a duct. A wash fluid may be introduced through the access device internal lumen into the milk duct. In the method, a volume of at least 2 ml of wash fluid may be present within the duct for a preselected time, and then at least a portion of the wash fluid is collected from the duct through the lumen of the access device. The method preferably further comprises massaging and squeezing the breast tissue after introducing the wash fluid but prior to and/or during collecting a portion of the wash fluid. Introducing the ductal access device typically comprises positioning a distal end of the catheter distal to the ductal sphincter in the breast duct. The access device preferably includes only a single lumen that extends into the duct. The preselected time may be less than one second, but will usually be in the range from one second to one hour.  
      Accordingly, there are any number of alternative combinations for defining the invention, which incorporate one or more elements from the specification, including the description, claims, and drawings, in various combinations or sub combinations. It will be apparent to those skilled in the relevant technology, in light of the present specification, that alternate combinations of aspects of the invention, either alone or in combination with one or more elements or steps defined herein, may be utilized as modifications or alterations of the invention or as part of the invention. It may be intended that the written description of the invention contained herein covers all such modifications and alterations.