Abstract:
The invention is directed toward a micro-endoscope assembly for the removal of tissue and cells from breast ducts comprising a cylindrical guide tube with a beveled distal end defining an internal cylindrical passageway, a first smaller cylindrical tube eccentrically formed in the cylindrical passageway of a smaller diameter than said tube internal cylindrical passageway to receive and guide an endoscope with a handle assembly, the smaller cylindrical tube forming together with an inner wall surface of the cylindrical guide tube second passageway. A second conduit of a smaller diameter than the smaller cylindrical tube is mounted in the second passageway to divide said second passageway into two separate divided sections and is of sufficient diameter to receive a laser fiber and a micro-endoscope is mounted in the smaller cylindrical tube and a laser is mounted in the second cylindrical tube in the second passageway. The assembly is inserted into a mammary duct and the interior of the duct is viewed until an abnormality is determined in the duct. The tissue and cells from the abnormality area are dislodged irrigated and aspirated through a suction channel to a removable collection device.

Description:
RELATED APPLICATION  
         [0001]    There are no related applications.  
         FIELD OF INVENTION  
         [0002]    The present invention is generally directed toward the detection of breast cancer and more specifically toward the detection and collection of cancer and/or abnormal growth tissue and cells in the mammary breast ducts of women.  
         BACKGROUND OF THE INVENTION  
         [0003]    A leading disease incurred by women is breast cancer. Breast cancer is the second leading cause of death for women of all ages and the leading cause of death for women aged 25-55.Approximately one in eight women will incur breast cancer in their lifetimes. The current medical standard for determining breast cancer in women is mammography. However mammography fails to detect up to 20% of breast cancers in women over 50 and up to 40% of breast cancers in younger women. Breast cancer grows slowly but under current techniques such as mammography the average detection is only on cancer growths which have been growing over seven years at which time the growth size of the cancer generally ranges between 1 and 2 cm. Almost 90% of all breast cancer originates in the mammary ducts, where it grows slowly in its initial stages.  
           [0004]    After detection breast cancer is generally treatable in three ways: surgery, radiation and chemotherapy. Surgery and radiation, of course, have risks and disadvantages well known to those of skill in the art. Chemotherapy also can be particularly disadvantageous as, for example, when the drugs involved cause sickness to the patient when they enter the blood stream.  
           [0005]    Endoscopic biopsy procedures are typically performed with an endoscope and an endoscopic biopsy forceps device (bioptome). The endoscope is a long flexible tube carrying fiber optics and having a narrow lumen through which the bioptome is inserted. The bioptome generally includes a long flexible coil having a pair of opposed jaws at the distal end and manual actuation means at the proximal end which opens and closes the jaws. During a biopsy tissue sampling operation, the surgeon guides the endoscope to the biopsy site while viewing the biopsy site through the fiber optics of the endoscope. The bioptome is inserted through the narrow lumen of the endoscope until the opposed jaws arrive at the biopsy site. While viewing the biopsy site through the fiber optics of the endoscope, the surgeon positions the jaws around a tissue to be sampled and manipulates the actuation means so that the jaws close around the tissue. A sample of the tissue is then cut and/or torn away from the biopsy site while it is trapped between the jaws of the bioptome. Keeping the jaws closed, the surgeon withdraws the bioptome from the endoscope and then opens the jaws to collect the biopsy tissue sample.  
           [0006]    A biopsy tissue sampling procedure often requires the taking of several tissue samples either from the same or from different biopsy sites. Unfortunately, most bioptomes are limited to large areas of entry and to taking a single tissue sample, after which the device must be withdrawn from the endoscope and the tissue collected before the device can be used again to take a second tissue sample.  
           [0007]    Attempts have been made to provide an instrument which will allow the taking of tissue samples within small duct areas. A simple double barrel catheter with adjacent lumens is disclosed in U.S. Pat. No. 6,221,622 with one of the lumens being used to irrigate the milk duct of a breast and the other lumen being used to aspirate the fluid which has entered the duct allowing a continuous flow of saline through the duct which hopefully carries enough cells and tissues for a biopsy. Problems in the use of such an instrument include the small size required by the narrow small diameter lumens which can be blocked or limit the flow of fluid back through the aspiration lumen and thus preclude significant tissue collection or cause duct collapse. While the &#39;622 Patent shows a small lumen size the size problem is magnified when the other existing prior art if the same were to be applied to breast ducts and the endoscope is to be used with mammary duct inspection because of the small size and thin cell walls of the mammary ducts.  
           [0008]    Thus almost all known multiple sample biopsy instruments are precluded from use with an endoscope because of their size and rigidity. These include the “punch and suction type” instruments disclosed in U.S. Pat. No. 3,989,033 and U.S. Pat. No. 4,522,206. Both of these devices have a hollow tube with a punch at the distal end and a vacuum source coupled to the proximal end. A tissue sample is cut with the punch and suctioned away from the biopsy site through the hollow tube. It is generally recognized, however, that dry suctioning tissue samples (i.e., without the use of an irrigating fluid) through a long narrow flexible bioptome is exceptionally difficult.  
           [0009]    The present device provides multiple sampling ability to an instrument which must traverse the narrow lumen of an endoscope or cannula housing an endoscope which in turn must traverse the small diameter of a breast duct. Numerous examples of prior art exist which are able to operate in a larger area such as U.S. Pat. No. 4,651,753 which discloses a rigid cylindrical member attached to the distal end of a first flexible tube. The cylindrical member has a lateral opening and a concentric cylindrical knife blade is slidably mounted within the cylindrical member. A second flexible tube, concentric to the first tube is coupled to the knife blade for moving the knife blade relative to the lateral opening in the cylindrical member. A third flexible tube having a plunger tip is mounted within the second flexible tube and a vacuum source (a syringe) is coupled to the proximal end of the third tube. A tissue sample is taken by bringing the lateral opening of the cylindrical member upon the biopsy site, applying vacuum with the syringe to draw tissue into the lateral opening, and pushing the second flexible tube forward to move the knife blade across the lateral opening. A tissue sample is thereby cut and trapped inside the cylindrical knife within the cylindrical member. The third flexible tube is then pushed forward moving its plunger end against the tissue sample and pushing it forward into a cylindrical storage space at the distal end of the cylindrical member. Approximately six samples can be stored in the cylindrical member, after which the instrument is withdrawn from the endoscope. A distal plug on the cylindrical member is removed and the six samples are collected by pushing the third tube so that its plunger end ejects the samples.  
           [0010]    It can thus be seen that the preferred mode of operation of virtually all existing endoscopic tools currently being used is that a gripping action at the distal end of the instrument is effected by a similar action at the proximal end of the instrument. Another endoscopic multiple sample biopsy device is disclosed in U.S. Pat. No. 5,171,255 which discloses a flexible endoscopic instrument with a knife-sharp cutting cylinder at its distal end. A coaxial anvil is coupled to a pull wire and is actuated in the same manner as conventional biopsy forceps. When the anvil is drawn into the cylinder, tissue located between the anvil and the cylinder is cut and pushed into a storage space within the cylinder. Several samples may be taken and held in the storage space before the device is withdrawn from the endoscope. Traditional biopsy forceps provide jaws which can grasp tissue frontally or laterally. Even as such, it is difficult to position the jaws about the tissue to be sampled. Lateral sampling is even more difficult.  
           [0011]    A traditional form of biopsy is disclosed in U.S. Pat. No. 5,542,432 which shows an endoscopic multiple sample biopsy forceps having a jaw assembly which includes a pair of opposed toothed jaw cups each of which is coupled by a resilient arm to a base member. The base member of the jaw assembly is mounted inside a cylinder and axial movement of one of the jaw assembly and cylinder relative to the other draws the arms of the jaws into the cylinder or moves the cylinder over the arms of the jaws to bring the jaw cups together in a biting action. The arms of the jaws effectively form a storage chamber which extends proximally from the lower jaw cup and prevents accumulated biopsy samples from being squeezed laterally out from between the jaws during repeated opening and closing of the jaws and the lower jaw cup enhances movement of the biopsy samples into the storage chamber. The device can hold up to four samples before it must be retrieved out of the endoscope. However, in some biopsy procedures it is sometimes desirous to retrieve more. In addition, it has been found that samples within the chamber can stick together and make determinations of which sample came from which biopsy site somewhat difficult.  
           [0012]    U.S. Pat. No. 5,538,008 discloses a multiple sample bioptome which purports to take several samples and transfers each sample by water pressure through a duct to the proximal end of the instrument, where each sample can be individually retrieved. The device includes a plastic jaw set biased in an open position and coupled to the distal end of an elongate tube, up to seven feet long. The tube defines a duct. A sleeve extends over the tube and a water flow passage is provided between the tube and the sleeve. An aperture is provided in the tube to permit the water flow passage to meet the duct at the distal end of the tube. Withdrawing the tube into the sleeve is disclosed to force the jaws closed and enable a sample to be cut from tissue and lodge in the duct. The water flow passage is disclosed to enable water to flow under pressure from the proximal end of passage to the distal end of the passage, through the aperture and into the distal end of the duct and to be aspirated to the proximal end of the duct, thereby transferring with it any sample contained in the duct to the proximal end where the sample can be retrieved.  
           [0013]    Generally in the field of surgery, mechanical cutters utilizing a reciprocal or rotating cutting element have been used to sever tissue of a patient. Cutting devices that use light energy to cut tissue are also well known in the art. Electro surgical devices for tissue excision or cauterization similarly have a long medical history. Such instruments have encountered numerous problems due to their one dimensional capabilities and have failed to meet many of the needs of a surgeon performing a surgical procedure.  
           [0014]    While some lasers are effective coagulators and cutters, certain other types of lasers, C 0   2  lasers for example, are effective at cutting tissue but are not good coagulators. Certain lasers are good coagulators but are poor tissue cutters. The YAG laser, for example, is sometimes used as a coagulator but is not considered to be a good tissue cutter.  
           [0015]    The ablation of tissue in various other regions of the body has been previously studied. U.S. Pat. No. 5,107,513 describes the general use of three types of lasers. Carbon dioxide (CO 2 ) laser radiation is intensely absorbed by water and thus acts as a surgical knife and vaporizer, its penetration depth in tissue being 0.03 mm. Argon lasers are minimally absorbed by water but intensely absorbed by hemoglobin and penetrate 1 to 2 mm in most tissue. These lasers are especially useful in coagulating bleeding points in small superficial vessels. Neodymium-Yttrium-Aluminum-Gamet (Nd:YAG) lasers are poorly absorbed by both water and hemoglobin. These lasers are able to penetrate large volumes of tissue, blood clots and coagulate large bleeding vessels. A Holmium laser with a 2100 nm wavelength has good cutting capabilities and its coagulating properties are similar to those of the Nd:YAG laser, penetrating to about 0.4 mm for most tissue. The Holmium laser was noted to be useful for the following applications: (1) in the gastrointestinal tract for bleeding ulcers, excision of lesions, recanalization of obstruction and arresting of massive bleeding; (2) in general surgery for cutting without bleeding; (3) in urology for treatment of the bladder; (4) for creation of vascular anastomoses; (5) for aneurysms, patent ducts, varicose veins and hemangiomas to generate thrombosis; (6) for dissolution of gall bladder stones by insertion of a fiber optic into the bile duct; (7) for destruction of tumors in the bronchial tree; (8) in gynecology for fallopian tube shrinkage and removal of polyps, benign tumors and septum and for ablation of the endometrium for menorrhagia; (9) in cardiac surgery for treatment of obstructed valves; and (10) in neurosurgery for removal of solid as well as vascular tumors.  
           [0016]    U.S. Pat. No. 5,147,354 describes the use of a mid-infrared laser endoscope for performing arthroscopy. Holmium:YAG and Holmium:YLF lasers with wavelengths in the 1800 to 2200 nm range are used for producing laser ablations in a fluid field. The radiation is said to be easily transmitted through a conventional quartz optical fiber.  
           [0017]    Thus, there is a need in the art for new and better micro-cannula/endoscope assemblies and methods for using same that can be used to directly visualize the mammary ducts of a breast where visualization is by means of endoscopic devices, direct visualization (as opposed to creation of photographic images) and offers the additional advantage that the equipment required is comparatively simple to use and is less expensive than the equipment required to create photographic displays from such images. In addition, there is a need in the art for a method of identifying diseased or abnormal tissue during surgical procedures so that immediate resection or biopsy of the identified tissue can be performed without the necessitating the use of additional instrumentation.  
         SUMMARY OF THE INVENTION  
         [0018]    The present invention is directed toward the detection, sample collection and/or treatment of abnormal growths and cancer located in the mammary ducts of women&#39;s breasts which in the present invention is when the cancer is typically between two and three years old with a size of about 0.2 mm. This is over 50 times more sensitive than a standard mammogram. According to a further aspect of the invention, a method is provided for retrieving one or more biopsy tissue sample(s) using a micro-endoscope assembly having irrigation and aspiration capabilities. The micro-endoscope assembly includes a proximal actuation handle, an elongate flexible member extending from the proximal actuation handle and having an irrigation conduit, a distal assembly located at the distal end of the biopsy instrument, and a fluid pressure device in fluid connection with the irrigation conduit.  
           [0019]    The method comprises the steps of: inserting the distal end of the micro-endoscope assembly into a lactiferous duct of the breast of a woman patient; viewing the inside of the duct as the distal end of the endoscope travels along the duct until a tissue abnormality is viewed; positioning the distal assembly proximate to a tissue to be sampled; detaching a tissue and/or cell sample from the tissue abnormality site using the beveled end of the cannula of the micro-endoscope assembly; introducing irrigation and subsequently a negative pressure through the fluid pressure device and the irrigation conduit while transporting fluid through the irrigation conduit to flush the tissue sample through an aspiration conduit from the distal end to the proximal end of the endoscope into a reservoir and member container therein and recovering the tissue sample.  
           [0020]    It is thus an object of the invention to provide a micro-endoscope assembly which can view the interior of a lactiferous duct to ascertain abnormalities and obtain tissue and cell samples from the site.  
           [0021]    It is an object of the invention to utilize a micro-cannula with an eccentrically mounted endoscope conduit to provide maximum room in the micro-cannula for other additional functions including aspiration, irrigation and laser treatment.  
           [0022]    It is yet another object of the micro-endoscope assembly invention to provide for the extraction of intraductal tissue for more reliable diagnosis with more precision and less trauma than convention biopsy procedures.  
           [0023]    It is also an object of the micro-endoscope assembly invention to provide for micro-endoscopic screening of defined groups of patients at high risk for breast cancer.  
           [0024]    It is an additional object of the micro-endoscope assembly invention to obtain direct real-time intraductal images allowing detection of cancerous and precancerous lesions and growths as small as 0.2 mm.  
           [0025]    It is an still additional object of the micro-endoscope assembly invention to extract tissue and cell samples for further diagnosis.  
           [0026]    It is also an object of the micro-endoscope assembly invention to create an endoscope assembly which can be easily handled by the physician.  
           [0027]    These and other objects, advantages, and novel features of the present invention will become apparent when considered with the teachings contained in the detailed disclosure which along with the accompanying drawings constitute a part of this specification and illustrate embodiments of the invention which together with the description serve to explain the principles of the invention.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0028]    [0028]FIG. 1 is an exploded side elevational view of the endoscope used in the present invention;  
         [0029]    [0029]FIG. 2 is an enlarged partial cross section of the lens end of the endoscope in FIG. 1;  
         [0030]    [0030]FIG. 3 is a perspective orientated view of the back end of the endoscope showing a light post and laser post;  
         [0031]    [0031]FIG. 4 is a perspective view of a portion of the front end of the micro-endoscope assembly;  
         [0032]    [0032]FIG. 5 is an enlarged cross sectional view taken along line  5 ′- 5 ′ on FIG. 4;  
         [0033]    [0033]FIG. 6 is an alternate embodiment of the micro-endoscope assembly invention; and  
         [0034]    [0034]FIG. 7 is another embodiment of a micro-endoscope. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0035]    The present invention is directed towards a micro-endoscope assembly  10  which can be used and inserted into the lactiferous ducts of the breast of a woman patient and a method for intraductal cytology. The lactiferous ducts generally range in number from about six to about twelve in women and lead from areas of the breast to the nipple where they are in parallel vertical orientation with each other. The ducts have a very thin cell wall ranging from 3 to 4 cells in thickness and are resilient. The ducts have a smooth inner surface and white color which resemble visually the interior of a standard PVC pipe.  
         [0036]    The best mode and preferred embodiment of the invention is shown in FIGS.  1 - 5 . The micro assembly  10  consists of tube or guide cannula  14  which seats and guides the endoscope  12 . The cannula  14  has an outer cylindrical wall  16  which defines an internal passageway which runs along its length to seat and guides the endoscope  12 . Cannula tube  14  may be a rigid steel tube ranging from 5-20 cm long having an outer diameter ranging from 0.5 mm to approximately 1.2 mm or alternatively may be a semi-rigid tube made of flexible or transparent plastic, or some other suitable material, and having the same or a longer length. The exterior of the cannula is marked with marking indicia  15  as seen in FIG. 4 so that the depth of penetration of the micro-endoscope assembly into the duct can be noted. The marking indicia can be in the form of rings of opaque, translucent or light reacting material or any other suitable geometry which is easily visible to the surgeons eye. The marking indicia can be printed onto the outer surface of the cannula or imbedded in the cannula structure material. Various cannula are envisioned to be interchangeable with the endoscope  12  by unscrewing one guide cannula from the endoscope front hub  18  and its associated connector member  20  and screwing one another on to the connector member. The hub member  18  has ports which are fluidly connected to a vacuum source  90  with a cell collection reservoir  92  containing a tissue and cell collection member  100  therein, the reservoir  92  being in fluid communication with an aspiration pump  200 .  
         [0037]    The endoscope  12  is provided with tube body  17  formed with objective lens  22  at its distal end and image guide  24  as is more clearly shown in FIG. 2. The endoscope  12  has a proximal end in the form of a back member  26  having a light post  27 , a laser post  28  and a video port  29  as seen in FIG. 3.  
         [0038]    The preferred cannula embodiment  30  has a cylindrical outer cannula or sheath  32  formed with a beveled distal end  34  as shown in FIG. 4 forming a shovel type nose  35 . The inner wall of sheath  32  defines a cylindrical inner channel  33  which has an inner cylindrical tube  36  eccentrically mounted thereon. The tube  36  defines the endoscope channel  37  and holds endoscope  12 . The inner cylindrical tube  36  is eccentrically mounted in cylindrical inner channel  33  to the wall of the cannula sheath  32  and its outer surface together with the inner surface of the sheath or tube  32  to define a moon shaped channel  38  which acts as a biopsy channel providing irrigation and aspiration. The irrigation/aspiration channel  38  can also be used as a port through which a laser, such as an Eximer laser, could be utilized. In that situation, the laser is inserted through the multiple purpose channel  38  until it reaches the patient&#39;s duct area containing cells and/or tissue showing abnormal characteristics.  
         [0039]    An alternate embodiment of the cannula  40  is shown in cross section in FIG. 6. This embodiment has a cylindrical outer cannula or sheath  42  which defines a cylindrical inner channel  43  in which an inner cylindrical tube  46  is eccentrically mounted to the wall of sheath  42 . The cylindrical tube  46  defines the endoscope channel conduit  47  to hold the endoscope  12 . A second smaller cylindrical tube  48  is eccentrically mounted in channel  43  adjacent to and integral with a portion of the wall of tube  46  and a wall of the cannula  42  to form a laser fiber channel  49  which holds laser fiber  50 . The cylindrical tube structure  46  divides the moon shaped channel up into two separated segments  52  and  54  which serve as the irrigation and aspiration channels for the assembly or for a channel for bundled illumination fibers and/or a mechanical tissue scraping or cutting device. These segmented channels allow the physician to irrigate and aspirate the area of the duct containing abnormal cells or structure and deposit the same onto a sample tissue and cell container in the form of a foam disk or porous substrate to provide a cytology sample of the duct area for examination. The aspiration conduit is of a diameter sufficient to retrieve biopsy samples from the distal end of the instrument.  
         [0040]    Another embodiment as shown in cross section in Figure is a micro-endoscope  60  which is constructed with an outer cannula or sheath  62  and an inner cannula or sheath  64  positioned within the chamber of cannula  62  to define an irrigation/aspiration channel  66  defined by the inner wall surface of cannula  62  and the outer wall surface of inner cannular  64 . The inner wall of cannula  64  defines a cylindrical inner chamber  65  which has an inner cylindrical tube  68  mounted therein. The tube  68  defines the image guide  69  and holds the lens. The inner cylindrical tube  68  is eccentrically mounted in cylindrical chamber  65  adjacent the inner wall of the cannula  64  and is substantially surrounded by a bundle of individual light fibers  80  and is adjacent to a laser fiber  82  which is positioned adjacent to outer wall of the inner cannula  64  within the bundle of laser fibers  82 .  
         [0041]    [0041]FIG. 1 also shows the endoscope  12  with the lens tube  17  and tube portion  19  coupled between hub  18  and back end  26 . Tube  19  includes a passageway in it&#39;s interior capable of holding fiber optic strands and/or illumination strands. Such strands run from video port  29 , through tube portion  19  into hub  18 . The strands run through hub  18  into the inner passageway of tube portion  17  though or outside of the working channel, as described in more detail below. These strands provide both a light source to the area of interest and a video source to the video port, allowing the physician to see an image of the area of the duct in which cytology is to be taken. The back end  26  is formed with a light source post connector  27  and laser post connector  28 . The tube portion  14  which has an outer diameter of approximately 1.2 mm has a working channel, a plurality of light fibers and a lens  22 . The light fibers  22  run the length of the guide tube  17  and provide light to the areas of interest. The light fibers are commercially available. The tube cannula  14  can alternately carry the light fibers or have them molded in the tube material. The lens  22  also runs longitudinally down inner passage of guide tube  17 . The laser fiber  50 ,  82  transmits the laser energy out the distal end of the endoscope via the contact laser tip to the surgical site. Suitable lasers which can be used with the invention are manufactured by Surgical Laser Technology, Inc.  
         [0042]    Because the cannula tube is of such a small outer diameter, the physician can manipulate the tube from the proximal end in order to scrape cells free of the tissue by engaging the same with the beveled end  34  and shovel tip  35 . The physician can then irrigate the location by ejecting saline water under pressure through the irrigation channel through the operation of the pump  200  which can be a syringe. This causes the saline water injected into the patient to mix with and carry the scraped biopsy cells and tissue. Such water and cells can be with drawn by a vacumn source  90  and deposited on the tissued collection strata  100  held in reservoir  92 . The tissue collection strata  100  can take the form of a small disk shaped device having layered porous foam which fits in a reservoir  92  of the aspiration channel of the micro-endoscope assembly. The disk  100  has several layers of foam having different porosity and density. One of the layers traps tissue particles and another layer traps cells. The disk can be removed after each biopsy usage and marked in a container as to the duct from which it was removed and the depth of length of duct where it came from.  
         [0043]    The endoscope  12  is used in conjunction with a video monitor and prismatic screen (not shown). The video port  29  is coupled to a video camera which is in turn coupled to a video monitor as is well known in the art and has an attached prismatic screen manufactured by Acueity Inc. The video camera may be of many different commercially available models, although CCD cameras are particularly useful in this type of application. Specifically, a Panasonic GS99-NTSC medical video endoscopy camera, from Matsushita Electric Corporation of America, has been found to be useful. Moreover, it has been found that in such a camera ¼ inch CCD chip is more advantageous than a ½ inch CCD chip, because it provides an image with smaller pixels. Such chips are included in CCD cameras and also are commercially available from many sources such as, for example, the Sony Corporation of America. The video monitor may be any of a number of commercially available video monitors.  
         [0044]    It is not necessary to include a prismatic screen to use the endoscope of the present invention. However, the use of such a screen is advantageous because, as described above, the screen provides an image with increased clarity and perception of depth by causing the brain of the viewer to interpret depth cues present in the image. This increased perception of depth is particularly advantageous in medical procedures like those that employ endoscopes because of the small dimensions involved and the limited lighting available in the interior of a patient&#39;s body.  
         [0045]    In operation the micro-endoscope assembly  10  using the rigid guide tube  14  is placed in a lactiferous duct in the patients breast after the nipple has been numbed The physician can view the interior of the duct, which has a white smooth surface, as the endoscope passes on its way through the duct to the area of interest which has an abnormal appearance and is found by watching the screen attached to video monitor. Once the duct area of interest is reached, the physician can manipulate the biopsy tube end  35  to dislodge the tissue and cells in the tissue area and retrieve cells and tissue from that area by irrigating the area and aspirating the fluid and tissue/cells to a collection site where the same are deposited on an easily removable cytology disc which traps cells and tissue or are poured into a sterilized plastic container, and taken to pathology for diagnostic testing. Ifthe lens of the endoscope  10  is needed to be cleared of blood or tissue the aspiration channel is used as an irrigation channel by applying a liquid under pressure through the use of a syringe attached to the irrigation port.  
         [0046]    The principles, embodiments and modes of operation of the present invention have been described in the foregoing specification. The invention that is sought to be protected herein, however, is not to be considered as limited to the particular forms disclosed, since these are to be regarded as illustrative rather than restrictive. Variations and changes may be made by those skilled in the art without departing from the spirit and scope of the invention. For example, the present invention is not limited to the particular dimensions or uses described, except as explicitly defined in the claims. Instead, the embodiments described here should be regarded as illustrative rather than restrictive. Variations and changes may be made by others without departing from the scope of the present invention as defined by the following claims: