Abstract:
An anorectal probe assembly comprising an anorectal probe, a sonar penetration balloon mounted to said probe, said balloon arranged to receive water to inflate within the rectal cavity a sigmoidscope having a bore into which the probe and balloon have sliding engagement and an adaptor having an anus penetration portion for insertion into the anus and an external portion mounted to the penetration portion wherein the adaptor includes a conduit extending from the penetration portion to the external portion such that on penetration of the anus, the conduit provides fluid communication between the rectal cavity and the external portion, said conduit further connectable to a vacuum source.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention refers to the application of ultrasound technology to obtain 3D images for precise diagnoses and surgical procedures. In particular, the invention relates to means of improving the quality and reducing obscurity of said images. 
       BACKGROUND 
       [0002]    High frequency ultrasound (up to 16 MHz) can penetrate tissue including the rectal wall and obtain detailed information to a depth of a few of millimetres from the tissue surface. However, for a colorectal cancer diagnosis, its application has been limited through poor contact between the ultrasound probe and rectal wall, especially for patients with a tumour, which makes the surface of rectal wall uneven. Further, the presence of entrapped air bubbles within the rectal cavity can obscure otherwise clear images. 
       SUMMARY OF INVENTION 
       [0003]    In a first aspect, the invention provides an anorectal probe assembly comprising an anorectal probe, a sonar penetration balloon mounted to said probe, said balloon arranged to receive water to inflate within the rectal cavity a sigmoidscope having a bore into which the probe and balloon have sliding engagement and an adaptor having an anus penetration portion for insertion into the anus and an external portion mounted to the penetration portion wherein the adaptor includes a conduit extending from the penetration portion to the external portion such that on penetration of the anus, the conduit provides fluid communication between the rectal cavity and the external portion, said conduit further connectable to a vacuum source. 
         [0004]    In a second aspect, the invention provides a method of removing air from a rectal cavity, the method comprising the steps of: inserting an anorectal probe and a sonar penetration balloon into a sigmoidscope; inserting the sigmoidscope into an adaptor, said adaptor having an anus penetration portion, an external portion and a conduit extending from the penetration portion to the external portion; inserting the sigmoidscope into the anus; inserting the anus penetration portion into the anus; connecting the conduit to a vacuum source at the external portion and consequently applying a vacuum to the rectal cavity; withdrawing air trapped between the rectal wall and the balloon through said conduit. 
         [0005]    The invention presented here is an anorectal probe assembly for a colorectal examination using ultrasound. The invention provides a better resolution of images by applying a vacuum to the rectal cavity in particular between the rectal wall and the inflated balloon so as to remove trapped air and improve the degree of contact between the balloon and cavity wall. The former solution is directed to reducing obscurity with the latter directed to improving overall image quality. 
         [0006]    The external portion may be a collar and the anus penetration portion may be a tube, with both required to be mounted, directly or indirectly, so as to allow the probe and sigmoid scope to pass therethrough. 
         [0007]    The external portion or collar may have a sealing ring mounted thereto which provides a circumferential sealing around the sigmoidscope. On insertion of the assembly into the anus, a sealed space is formed with the rectal wall, the adaptor and the sealing engagement between the adaptor and sigmoidscope providing boundary defining this space. On application of the vacuum through the conduit, a negative pressure is established in the rectal cavity, leading to the removal of entrapped air. 
         [0008]    To further enhance the seal formed by the adaptor, the external portion may include a plurality of orifices in a contact face, which on insertion of the adaptor comes into proximity with the anus. The orifices may be in fluid communication with the conduit and consequently in communication with the vacuum source. On application of the vacuum source, the orifices apply a negative pressure to the anus and so sealing around the anus to further enhance the sealing effect of the adaptor. 
         [0009]    Within the external portion may be positioned a sealing ring valve which may comprise an annulus with holes corresponding to the orifices. The sealing ring may be rotatable such that rotating from a first position may permit the vacuum source to pass through the orifices and a second position which seals the orifices, and so isolating the vacuum source from the orifices, breaking the seal. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0010]    It will be convenient to further describe the present invention with respect to the accompanying drawings that illustrate possible arrangements of the invention. Other arrangements of the invention are possible, and consequently the particularity of the accompanying drawings is not to be understood as superseding the generality of the preceding description of the invention. 
           [0011]      FIGS. 1A to 1C  are various views of an anorectal probe assembly according to one embodiment of the present invention; 
           [0012]      FIGS. 2A to 2C  are various views of a sonar penetration balloon mounting according to one embodiment of the present invention; 
           [0013]      FIGS. 3A to 3C  are various views of a coupling according to one embodiment of the present invention; 
           [0014]      FIGS. 4A to 4D  are various views of an adaptor according to an embodiment of the present invention; 
       
    
    
     DETAILED DESCRIPTION 
       [0015]      FIGS. 1A ,  1 B and  1 C show an anorectal probe assembly  5  according to one embodiment of the present invention. The assembly  5  comprises an anorectal probe  10  having a shaft  12  for insertion into the rectum and at a distal end of the shaft  12 , an ultrasound transducer  11  for creating ultrasound images of the surrounding tissue. An example of such a probe is a BK Medical 2050 Anorectal Transducer. 
         [0016]    Mounted to the probe  10  is a balloon  20  which is used to inflate within the rectum by filling with water. Inflating the balloon enlarges the rectum so as to create a clearance between the transducer  11  to improve image quality. The balloon  20  is mounted to the probe through the use of a coupling  15  which fits onto the probe  10  by sliding down the shaft  12  and securing to the probe about an enlargement between the handle and the shaft. The balloon  20  is clamped to the coupling  15  using a quick sealing ring  40  which in this case has a bayonet fitting, that is, a push/twist arrangement to provide a quick clamping effect at the open end of the balloon. 
         [0017]    At the distal end  13  of the probe  10  is fitted an end cap  30  which is placed on the probe with the balloon  20  being fixed to the end cap using an O-ring (not shown) or other resilient clamp so as to prevent the balloon inflating longitudinally within the rectum. The end cap  30  therefore acts to restrain the direction of inflation of the balloon and so confine the balloon expansion to the desired area proximate to the transducer  11 . Mounted over the balloon  20  is a sigmoidscope  25  and mounted over the top of the sigmoidscope  25  is an adaptor  35 . 
         [0018]    A procedure according to an embodiment of the present invention may commence with a pre-clinical scan whereupon the end cap  30  is mounted to the probe  10  at the distal end  13 . The coupling  15  is then fitted down the shaft  12  and secured to the handle with the probe shaft  12  then inserted into the balloon  20  and clamping one end of the balloon to the coupling  15  using the quick sealing ring  40  and the opposed end of the balloon  20  clamped to the end cap  30  using an O-ring or simple by a nylon string. 
         [0019]    To initialise the assembly, the balloon  20  is filled with water and air bubbles expelled from the inflated balloon  20 . The balloon is then deflated, removing the water but preventing the inflow of air so as to prevent the balloon having any air bubbles present prior to use. 
         [0020]    To commence the clinical scan, the sigmoidscope  25  is inserted in the adaptor  35  with the adaptor  35  connected to a vacuum source such as may be found in an operating theatre or day surgery clinic. The sigmoidscope  25  with the adaptor  35  mounted thereto is inserted into the anus and subsequently to the rectum. The sigmoidscope allows the use of CCD or other devices to do a preliminary visual scan around the rectum. 
         [0021]    The probe  10  with the balloon  20  mounted thereto is then inserted through the sigmoidscope into the rectum so as to place the sensor  11  proximate to the area to be investigated by the operator. The adaptor is moved to the anus with the anus penetrating section  85  inserted into the anus so as to bring the external portion or collar  100  proximate to the anus. The vacuum source is engaged with the adaptor through nozzle  105  leading to the orifices  120  engaging the anus in suction and so sealing the anus. At this stage, the rectal cavity is now sealed. With the orifices sealed, the vacuum evacuates the interstitial space between the probe and the rectal wall. The balloon is then inflated with water. With no air bubbles within the rectal cavity to form discontinuities, the balloon can then come in intimate contact with the rectal wall and possibly adopt the shape of any lumps or tumours within the rectum so as to provide a largely uninterrupted layer of the balloon wall against the rectal wall. From this point, the ultrasound scan can begin and images produced to the best available quality. 
         [0022]      FIGS. 2A to 2C  and  3 A,  3 C provide detailed views of the assembly of the balloon  20  to the coupling  15 .  FIG. 2A  shows the quick sealing ring  40  which is used to clamp the open end  50  of the balloon to the coupling  15 . In this embodiment, the quick sealing ring  40  has a bayonet attachment whereby projections  45 A, B fit within recesses  75 A, B in the coupling. By placing the balloon within the opening  76 , the balloon is then compressed and clamped by the insertion of the ring  40  into the bayonet fitting  45 A, B,  75 A, B and so providing a sealing clamp within the opening  76 . This leads to a separation of the inside space of the balloon into 2 chambers, a left chamber towards the balloon stopper and a right chamber towards to the handle of probe. The left chamber is relatively smooth, that is free from ridges and other discontinuities, such that the air could be removed out easily and has no place to hide the air inside. The right chamber could hold some hidden air or leaked air if it happened to avoid the air move to the scanning area. 
         [0023]    At the opposed end, the end cap  30  is mounted to the distal end  13  of the probe with the balloon fitting over the top of the shaft  12  of the probe. The end cap  30  may be a metal part adhered to the probe to ensure a permanent or semi-permanent engagement. Alternatively, the end cap  30  may be a plastic part which is selectively removable. In this embodiment, the end cap  30  may be mounted to the probe through a snap fitting to provide a secure connection, but also to be able to detach the end cap  30  after use. Being a plastic part, the snap fit end cap may therefore be disposable, and so avoid issues of cleaning and disinfection for re-use. 
         [0024]    Further, the end cap, either for the re-usable or disposable version, may be rounded to provide for a more comfortable insertion into the patient. 
         [0025]    Once in place, an O-ring (not shown) fits over the balloon so as to clamp the far end  60  of the balloon  20  into the groove  55  of the end cap  30 . Thus the balloon is now fully secured, ready for inflation. Turning to the coupling  15  in particular, the coupling fits over the shaft  12  of the probe and is sealed through a seal  80  within the coupling  15 , water inlet  70  can then be connected to a water source so as to flow water through the opening  76  so as to inflate the balloon. 
         [0026]      FIGS. 4A to 4D  show the adaptor  35  and its connection with the sigmoidscope  25 . The adaptor itself comprises an assembly which may be of a unitary construction or an assembly having an anus penetration section  85  in the form of a tube mounted to a front ring  90  and subsequently mounted to an external portion  100  in the form of a collar. Mounted between the collar  100  and the front ring  90  is a vacuum ring valve  95  which is rotatable within the adaptor  35 . 
         [0027]    Within the front ring  90  is placed an array of orifices  120  which are in communication with a conduit  104 . The conduit  104  extends from the anus penetration portion  85  to the external portion  100  which in turn is connected to a nozzle  105 . The nozzle  105  is connectable to a vacuum source and thus through the conduit  104 , the anus penetration portion  85  can provide vacuum communication between the rectal cavity and the vacuum source on insertion. With the orifices  120  also in communication with the conduit  104 , the orifices  120  also provide a vacuum seal against the anus when the adaptor is brought proximate to the anus and so providing a seal for the rectal cavity. Once the anus is sealed the vacuum is provided through the conduit  104  so as to remove any air between the probe and the rectal wall prior to inflation of the balloon  20 . 
         [0028]    To ensure a complete seal between the sigmoidscope  25  and the adaptor  35 , the collar  100  includes a sealing ring  110  which permits a sliding engagement between the sigmoidscope and adaptor but when stationary provides sufficient circumferential contact so as to seal against any loss of negative pressure created by the vacuum within the rectal cavity.