WO2008101286A1

WO2008101286A1 - A channel seal for an endoscope

Info

Publication number: WO2008101286A1
Application number: PCT/AU2008/000224
Authority: WO
Inventors: Jon Long; Roderick Galantai; Steven Kritzler
Original assignee: Carern Marketing Pty Ltd
Priority date: 2007-02-21
Filing date: 2008-02-20
Publication date: 2008-08-28

Abstract

A channel seal (10) for an endoscope. The channel seal (10) comprising a body (12) with an internal passage (14) therethrough and an integrally formed frangible member (20) occluding the passage (14).

Description

A CHANNEL SEAL FOR AN ENDOSCOPE

Technical Field

The present invention relates to a channel seal for an endoscope.

The invention has been primarily developed for sealing the proximal end of the biopsy channel of an endoscope and will be described hereinafter with reference to this application.

Background of the Invention Any discussion of the known devices throughout this specification should in no way be considered as an admission that such devices are widely known or presently form part of common general knowledge in the field of the invention

The quality of the reprocessing of reusable medical instruments is a fundamental factor in controlling the level of subsequent post-procedural infections associated with such instruments.

Broadly, such reprocessing can be broken into two main steps: firstly cleaning; and secondly disinfection (which includes sterilisation). Neither of these steps is considered more important than the other. In relation to medical infection prevention, inadequately cleaned instruments can not be reproducibly disinfected. In recent decades reprocessing efficacy has become even more challenging as medical instruments have become more complex. Further, the ancillaries used with these instruments, which also require reprocessing, are themselves often complex.

Flexible endoscopes are used for a variety of diagnostic and interventional procedures associated with various body cavities. These instruments are constructed from a variety of materials including metals, glasses, adhesives and flexible polymers. These materials limit the chemical compositions, thermal and physical conditions which can be used in the reprocessing of these instruments due to their chemical, physical and thermal sensitivity. The instrument reprocessing of the large and increasing range of flexible endoscopes is very difficult. For example, currently, flexible endoscopes cannot be autoclaved or put under significant positive or negative pressure and have proved to be sensitive to extremes of pH. The same sensitivity is true of many of the ancillaries used with flexible endoscopes, which must also be reprocessed prior to reuse.

Further, many flexible endoscopes feature one or more hollow channels or lumens, one of which is known as the "biopsy channel". The biopsy channel is normally a channel of approximately 2.8 mm in diameter through which various ancillaries (e.g. biopsy forceps, biopsy snares) are designed to be passed.

Other channels, particularly in gastrointestinal endoscopes, are used to: pass air into the gastrointestinal tract for inflation to enable clearer vision of its surfaces for diagnostic purposes; pass water to wash a video camera lens; or suck liquids from the tract which may obscure vision of mucosal surfaces. In gastrointestinal endoscopy, the gastrointestinal tract is usually under positive air pressure to ensure the portion being studied remains in an inflated state. For this reason, a seal is placed over the proximal end of the biopsy channel to: ensure that the air cannot leak out; and protect the endoscopist and nearby staff from having human secretion blown back from the body cavity to the atmosphere via the biopsy channel by the positive pressure therein.

The effective seal of the biopsy channel also needs to be effective whilst ancillaries are passed down the biopsy channel, since these ancillaries can have a significantly smaller diameter than the channel and can allow human secretion to be forced up the biopsy channel by air pressure whilst the ancillaries are in use. For this reason, biopsy channel seals are supplied with all biopsy equipped endoscopes. The seals are supplied with a slit, a hole or a hole and a slit to allow for the passage of ancillaries into the proximal end of the biopsy channel (to tissue surfaces beyond the biopsy channel's distal end) whilst concurrently blocking the passage of air or other secretions past the seal.

Flexible endoscope biopsy channels have a stainless steel fitment at their proximal end which sits proud of the control body of the endoscope. The end of the fitment has a peripheral annular flange. Biopsy channel seals are made of flexible polymers (which can be elastomers) or plasticised polymers and are manufactured to stretch fit over the flange sufficiently tightly to ensure they are not easily displaced from the flange in the course of a diagnostic procedure. However, they are not difficult to place over or remove from the flange before and after each procedure. Most endoscope manufacturers employ the same size of flange throughout their range. Each manufacturer thus tends to have its own sized biopsy channel seal.

Hitherto, there are three main types of biopsy channel seals for endoscopes.

The first type of channel seal has a concentric slit which is sufficiently tight to ensure no leakage of human secretion and a minimal leakage of air both whilst in isolation and whilst an ancillary device is passing through the seal into the biopsy channel.

The second type of channel seal instead has a concentric hole of sufficient diameter to seal around the smallest diameter ancillary device which is designed to pass through it. These types of seal also have an integral, removable plug which can be clipped onto the seal over the concentric hole so as to ensure an air tight seal whilst no ancillary instrument is sealing the hole. The advantage of this type of seal is friction between the channel seal and the ancillary instrument in either direction through the seal, is significantly less than that generated by the slit in the first type of seal.

The third type of biopsy channel seal has a concentric hole similar to that described in the second type, but with a slightly larger diameter. This seal is also fitted with a plug which, when in place, ensures no leakage of human secretion or air. However, the third type of seal also has a concentric slit in the plug. If a larger diameter ancillary device is to be inserted into the biopsy channel, then the plug is removed from the seal and the ancillary device can pass through the hole with less friction than in the cases of either the first or second devices. If a smaller diameter ancillary device is to be used, then the plug is inserted over the hole and the device passed through the slit therein.

The shape of these biopsy channel seals are complex because of their need to fit over a flange. Further, the small size, and shape, of the known seals is such that it is impossible to see all of their internal surfaces making them difficult to clean. The internal surfaces of biopsy channel seals become contaminated by human secretions in the course of their use. It is extremely difficult to thoroughly clean all of their internal surfaces with the brushes normally used to clean them and whose bristles simply cut through the fluid without completely removing it. A known mode of cleaning channel seals for re-use prior to disinfection is to follow brushing by placing them into an ultrasound bath to which is added an appropriate cleaning solution. However, sonication is very much less effective for flexible objects (compared to rigid) as they absorb a considerable proportion of the wave energy. For this reason the ultrasonic cleaning of biopsy seals as part of their reprocessing for re-use is known to be problematic. It is also known that the disinfection process is very much less effective for articles which have not been thoroughly cleaned than for clean articles. For these reasons, the re-use of biopsy channel seals presents a very real threat of cross- infection between patients.

In modern medical practice significant debate has arisen over the progressive replacement of reusable items by single use disposable items. Due to limited financial resources the cost of an item is often the basis of the decision as to whether or not an item is to be disposable or reprocessed. As part of this assessment the cost of the article and also the cost of its reprocessing in terms of cleaning agents, disinfectant and labour are also taken into account. A further important factor which should be taken in account by responsible practitioners in deciding as to the "disposability" of an item is the balance of cost against the potential risk to patients resulting from incomplete reprocessing which leads to cross infection.

Known biopsy channel seals are not considered single use purely because of their cost.

The most substantial part of the cost associated with the manufacture of a biopsy channel seal is associated with the complexity of the moulding tooling and the number of steps involved in its manufacture.

The shape of known biopsy channel seals results in complex, and thus expensive, moulding tools. This shape involves various undercuts, a well known source of complexity and considerable added cost in the manufacture of polymer moulding tools. The various concentric holes and slits in the seals necessitate either extra manufacturing steps to add these orifices during the moulding cycle or else that considerable further complexity be built into the moulding tools to introduce these orifices. Not only does this extra "in tool" process add a very large cost factor but it can considerably slow the moulding cycle, another major cost impost. Alternatively, holes and/or slits are cut into the moulding after it has been removed from the moulding tool.

On some occasions an opening (e.g. a slit or a hole) in a biopsy channel seal can become compromised due to: the rough usage of an ancillary biopsy channel device in the seal; the use of non standard devices such as oversized syringes; or the possible need for more cycles of device insertion into and through the seal than is normal. For this reason many practitioners prefer to use second or third types of seals described previously, particularly the second type. This is because this type of seal has the facility to close over the seal orifice by virtue of a plug which can fit, by friction, into the distal end of the seal over the opening thereby guaranteeing an effective seal even when the membrane is so compromised.

Object of the Invention It is the object of the present invention to provide a channel seal for an endoscope that is able to be manufactured at a cost suitable for single use then disposal.

Summary of the Invention

Accordingly, in a first aspect, the present invention provides a channel seal for an endoscope, the channel seal comprising: a body with an internal passage therethrough; and an integrally formed frangible member occluding the passage.

The frangible member is preferably adapted to rupture in response to force above a predetermined level being applied thereto. The predetermined level of force required to rupture the member is preferably approximately equal to that generated by an adult person pushing an endoscope ancillary instrument.

The frangible member is preferably sufficiently resilient to substantially occlude the passage after rupturing, in the absence of any objects therein. The frangible member is preferably sufficiently resilient to substantially occlude the passage after rupturing, in the absence of any objects therein, in the presence of a pressure differential across the frangible membrane of about 3 to 9 Psi.

In one embodiment, the frangible member is of constant thickness across the passage. In another embodiment, the frangible member includes a region of weakness therein, preferably in the form of a reduced thickness portion, hi one form, the reduced thickness portion is preferably a diametric depression across one or both sides of the frangible member, most preferably two aligned diametric depressions. In another form, the reduced thickness portion is preferably circular, most preferably bounded by frusto-conical walls. The thickness of the reduced thickness portion is about 0.2 mm thick. The thickness of the remainder of the frangible member (i.e. remote the reduced thickness portion) is preferably about 1.6 mm thick.

In a second aspect, the present invention provides a channel seal for an endoscope, the channel seal comprising: a body with an internal passage therethrough; and an integrally formed member occluding the passage, wherein the occluding member has a region of weakness formed therein.

The occluding member is preferably adapted to rupture in response to force above a predetermined level being applied thereto. The predetermined level of force required to rupture the member is preferably approximately equal to that generated by an adult person pushing an endoscope ancillary instrument.

The body preferably also includes a first internal recess adapted to engage an external flange of a first corresponding size on the proximal end of an endoscopic channel. The body preferably also includes a second internal recess, of differing size to the first internal channel, adapted to engage an external flange of a second corresponding size on the proximal end of an endoscopic channel. The frangible member is preferably longitudinally positioned between the first and the second internal recesses.

The body preferably includes an integrally formed plug which, upon insertion into an end of the body, is adapted to substantially seal the passage. Alternatively, the body preferably includes an integrally formed plug which, upon insertion into either end of the body, is adapted to substantially seal the passage. The body preferably includes a flexible arm integrally formed between the body and the plug. The plug preferably also includes: an internal passage therethrough; and an integrally formed frangible member occluding the passage.

In one embodiment, the plug frangible member is of constant thickness across the passage.

In another embodiment, the plug frangible member includes a region of weakness therein, preferably in the form of a reduced thickness portion. The reduced thickness portion is preferably a diametric depression across one or both sides of the frangible member. The thickness of the reduced thickness portion is preferably about 0.2 mm thick. The thickness of the remainder of the plug frangible member (i.e. remote the reduced thickness portion) is preferably about 1.6 mm thick.

The channel seal is preferably moulded from at least one polymer elastomer or at least one polymer/plasticiser combination. For example, Santoprene (Trade Mark) or Dow Corning TPSIV 3010-50A (Trade Mark).

In a third aspect, the present invention provides a method of moulding a channel seal for an endoscope, the method comprising moulding a channel seal body with an internal passage therethrough and an integrally formed frangible member occluding the passage.

In one embodiment, the method includes moulding the frangible member with a constant thickness across the passage.

In another embodiment, the method includes moulding the frangible member with a region of weakness therein, preferably in the form of a reduced thickness portion. In one form, the method preferably includes moulding a diametric depression across one or both sides of the frangible member, most preferably two aligned diametric depressions. In another form, the method preferably includes moulding a circular reduced thickness portion, most preferably bounded by frusto-conical walls. The thickness of the reduced thickness portion is about 0.2 mm thick. The thickness of the remainder of the frangible member (i.e. remote the reduced thickness portion) is preferably about 1.6 mm thick. The method preferably includes moulding an integrally formed plug with the channel seal which, upon insertion into an end of the body, is adapted to substantially seal the passage. Alternatively, the method includes moulding an integrally formed plug with the channel seal which, upon insertion into either end of the body, is adapted to substantially seal the passage. The method preferably also includes moulding an integrally formed flexible arm between the body and the plug.

The method preferably includes moulding the channel seal from at least one polymer elastomer or at least one polymer/plasticiser combination. For example, Santoprene (Trade Mark) or Dow Corning TPSIV 3010-50A (Trade Mark).

Brief Description of the Drawings

Preferred embodiments of the present invention will now be described, by way of examples only, with reference to the accompanying drawings wherein:

Fig. Ia is a top view of a first embodiment of a channel seal;

Fig. Ib is a side view of the channel seal shown in Fig. Ia;

Fig. Ic is an end view of the channel seal shown in Fig. Ia;

Fig. Id is a cross sectional side view of the channel seal shown in Fig. Ia along line Id; Fig. Ie is a top view of the channel seal shown in Fig. Ia;

Fig. 2a is a top view of a second embodiment of a channel seal;

Fig. 2b is a side view of the channel seal shown in Fig. 2a;

Fig. 2c is an end view of the channel seal shown in Fig. 2a;

Fig. 2d is a cross sectional side view of the channel seal shown in Fig. 2a along line 2d; Fig. 2e is a top view of the channel seal shown in Fig. 2a;

Fig. 3 a is a top view of a third embodiment of a channel seal;

Fig. 3b is a side view of the channel seal shown in Fig. 3a;

Fig. 3c is an end view of the channel seal shown in Fig. 3a;

Fig. 3d is a cross sectional side view of the channel seal shown in Fig. 3a along line 3d; Fig. 3e is a top view of the channel seal shown in Fig. 3 a;

Fig. 4a is a top view of a fourth embodiment of a channel seal;

Fig. 4b is a side view of the channel seal shown in Fig. 4a;

Fig. 4c is an end view of the channel seal shown in Fig. 4a;

Fig. 4d is a cross sectional side view of the channel seal shown in Fig. 4a along line 4d; Fig. 4e is a top view of the channel seal shown in Fig. 4a;

Fig. 5a is a top view of a fifth embodiment of a channel seal;

Fig. 5b is a side view of the channel seal shown in Fig. 5a;

Fig. 5c is an end view of the channel seal shown in Fig. 5a; Fig. 5d is a cross sectional side view of the channel seal shown in Fig. Ia along line 5d;

Fig. 5e is a top view of the channel seal shown in Fig. 5a;

Fig. 6a is a top view of a sixth embodiment of a channel seal;

Fig. 6b is a side view of the channel seal shown in Fig. 6a;

Fig. 6c is an end view of the channel seal shown in Fig. 6a; Fig. 6d is a cross sectional side view of the channel seal shown in Fig. 6a along line 6d;

Fig. 6e is a top view of the channel seal shown in Fig. 6a;

Fig. 7a is an end view the channel seal shown in Fig. 5a with a syringe head adjacent thereto;

Fig. 7b is a cross sectional side view of the channel seal and syringe head shown in Fig. 7a along line 7b;

Fig. 7c is an end sectional side view of the channel seal and syringe head shown in Fig. 7a after insertion of the head into the seal;

Fig. 7d is a cross sectional side view of the channel seal and syringe head shown in Fig.

7c along line 7c; Fig. 8a is a top view of a seventh embodiment of a channel seal;

Fig. 8b is a side view of the channel seal shown in Fig. 8a;

Fig. 8c is an end view of the channel seal shown in Fig. 8a;

Fig. 8d is a cross sectional side view of the channel seal shown in Fig. 8a along line 8d;

Fig. 8e is a top view of the channel seal shown in Fig. 8a; Fig. 8f is a partial enlarged detail cross sectional side view of the channel seal shown in

Fig. 8a along line 8f;

Fig. 8g is a further enlarged detail view of the circled region shown in Fig. 8f;

Fig. 8h is a side view the channel seal shown in Fig. 8a with a syringe head adjacent thereto; Fig. 8i is a cross sectional side view of the channel seal and syringe head shown in Fig. 8h along line 8i;

Fig. 8j is an end view the channel seal shown in Fig. 8a with a biopsy forcep therethrough; and Fig. 8k is a cross sectional side view of the channel seal and biopsy forcep shown in Fig. 8j along line 8k.

Detailed Description of the Preferred Embodiments

Figs. Ia to Ie show a first embodiment of channel seal 10 adapted for sealing the proximal end of the biopsy channel of an endoscope (not shown). The seal 10 is moulded from Santoprene (Trade Mark) or Dow Corning TPSIV 3010-50A (Trade Mark).

The seal 10 has a generally cylindrical body 12 with a generally longitudinal internal passage 14 therethrough. The passage 14 has a first internal recess 16 adapted to engage a correspondingly sized flanged stainless steel fitting provided on the proximal end of the biopsy channel of an endoscope, as is well known to persons skilled in the art. The passage 14 also includes a second internal recess 18, which is of a different size (i.e. is smaller) than the first internal recess 16. The recess 18 is adapted to engage another correspondingly sized flanged stainless steel fitting provided on the proximal end of the biopsy channel of an endescope. Accordingly, the seal 10 can be used with endoscopes of two different manufacturers.

The seal 10 is approximately 16.5 mm long and has an external diameter of approximately 14.5 mm. The passage 14 has an internal diameter of approximately 5.7 mm between the first and the second recesses 16 (excluding the frangible member 20).

A frangible member 20, which is integrally moulded with the body 12, prevents the flow the flow of fluids or other material through the passage 14. Accordingly, when the seal 10 is placed over the proximal end of the biopsy channel, it ensures that air cannot leak out of the biopsy channel. The seal 10 also protects the endoscopist and nearby staff from having human secretion blown back from the body cavity that the endoscopist is investigating to the atmosphere by positive pressure which is often generated therein.

The frangible member 20 has a pair of aligned diametric grooves 22a and 22b in its external surfaces. The deepest part of each of the grooves 22a and 22b are separated by approximately 0.2 mm. The remainder of the frangible member 20 is approximately 1.6 mm thick. The grooves 22a and 22b provide a region of weakness in the frangible member 20 which allow it to be easily ruptured by an endoscopist pushing an ancillary endoscopic instrument against the frangible member 20 in order to insert it into and through the biopsy channel. When the instrument is removed, the resilient nature of the seal material causes the, now separated, parts of the frangible member 20 to return to the position shown in Figs. Ia to Ie, substantially re-sealing the proximal end of the biopsy channel. More particularly, the ruptured frangible member 20 will maintain a substantially gas and fluid type seal in the presence of about 3 to 9 Psi pressure in the biopsy channel.

The unitary seal 10 is significantly simpler, and thus less expensive, to produce than existing biopsy channel seals as it does not require the provision of any accurately sized openings or slits therein during moulding manufacture. As a result, the seal 10 is advantageously suitable for economical single use followed by disposable due to its reduced manufacturing costs.

Further, as the seal is designed to be used as a single use item it may be constructed from cheaper materials than those commonly used for reusable seals, and these cheaper materials can still exhibit design features which satisfy all the relevant requirements of a single medical procedure but which otherwise may fail over repeated multiple cycles of use. This is especially the case considering the required reprocessing steps associated with endoscopic instruments. In particular, the seal 10 may be manufactured by moulding in a single step without the need for any additional manufacturing, moulding or cutting steps either in the moulding tool or after the subsequent removal of the seal 10 from the tool.

Additionally, the (relatively) thin frangible member 20 ruptures without causing any damage to any endoscopic or other devices that may be used in the course of a medical procedure such as syringes, biopsy forceps, biopsy snares or cauterising tools. Further, in the event that any leakage does occur it is so slight as to not present a significant problem. Also, the flexibility, resiliency and thickness of the frangible member 20 serve to allow the material of the frangible member to deform and substantially seal around such an introduced ancillary device after it has ruptured the frangible member 20, such that no significant leakage of human secretion or air occurs or, if it does, it is so slight as to present no significant problem. Additionally, the ruptured frangible member 20 does not impose any significant frictional forces against any ancillary device passing therethrough, and thus does not cause any buckling, kinking or other adverse effect. This facilitates the passage of such flexible ancillary devices and makes procedures faster, easier and minimises the chance of damage to the ancillary devices.

Figs. 2a to 2d show a second embodiment of a biopsy channel seal 30. The construction, operation, manufacture and advantages of the seal 30 are similar to the seal 10 previously described and like reference numerals have been used to indicated like features. However, the seal 30 also includes a plug 32. The plug 32 has a first end 32a of a relatively larger diameter and a second end 32b of a relatively smaller diameter. The first end 32a is adapted to frictionally engage and substantially seal the relatively larger end of the passage adjacent the first internal recess 16. The second end 32b is adapted frictionally engage and substantially seal the relatively smaller end of the passage 14 adjacent the second internal recess 18.

The plug is attached to the body 12 by a flexible arm 36. The body 12, plug 32 and arm 36 are all integrally moulded in a single process so as to preserve the economic advantages already described with relation to the seal 10. The arm 36 also includes a tab 38 to assist in gripping and positioning of the plug 32 in alignment with the passage 14 and raised moulded letters O and P on opposite sides of the arm 36. The letters O and P indicate which side of the seal 10 attaches to endoscopes manufactured by Olympus and Pentax respectively.

The plug 32 provides additional assurance that no significant leakage of secretion or air occurs at any time during the procedure. Further, the plug 32 can be readily detached should the endoscopist wish to introduce or reintroduce an ancillary device. The plug 32 can also be attached or not dependant upon the wishes of the practitioner and the requirements of the procedure. The arm 36 is of sufficient length so that the plug 32 can be easily and neatly pressed into either end of the passage 14 and remain therein by virtue of a friction or interference fit.

Figs. 3a to 3e show a third embodiment of seal 40. The construction, operation, manufacture and advantages of the seal 40 are similar to the seal 30 previously described and like reference numerals have been used to indicated like features. However, in this embodiment, the plug 32 also includes an internal passage 42 occluded by a frangible member 44 with a line of weakness established by opposed diametric grooves 44a and 44b. This allows the plug's frangible member 44 to rupture, in a manner similar as was previously described in relation to the body's frangible member 20, after piercing by instruments (whilst engaged with the body 14 of the seal 40) and to also substantially reseal the end of the endoscopic channel after removal of such instruments.

The two frangible members 20 and 44, one or both of which can be punctured by an ancillary device, also provide an extra assurance of resistance to leakage of both secretions and air from the biopsy channel.

Figs. 4a to 4e show a fourth embodiment of seal 50. The construction, operation, manufacture and advantages of the seal 50 are similar to the seal 10 previously described and like reference numerals have been used to indicated like features.

Figs. 5a to 5e show a fifth embodiment of seal 60. The construction, operation, manufacture and advantages of the seal 60 are similar to the seal 10 previously described and like reference numerals have been used to indicated like features. However, in this embodiment, the plug 32 is only able to engage the end of the body 14 adjacent the internal recess 16. More particularly, the plug 32 includes an external barbed flange 62 adapted to positively engage the first internal recess 16. The plug 32 does not include a region of weakness.

Figs. 6a to 6e show a sixth embodiment of seal 70. The construction, operation, manufacture and advantages of the seal 70 is similar to the seal 60 previously described and like reference numerals have been used to indicated like features. However, in this embodiment, the plug 32 does include a region of weakness 72 established by the opposed diametric grooves 74a and 74b.

Figs. 7a to 7d demonstrate how a syringe head 80 is able to pierce the seal 70 in order to allow, for example, an endoscopist to administer fluid via the endoscopic channel.

Figs. 8a to 8g show a seventh embodiment of seal 90. The construction, operation, manufacture and advantages of the seal 90 is similar to the seal 70 previously described and like reference numerals have been used to indicated like features. However, in this embodiment, the reduced thickness portion 20 is circular and bounded by a frusto-conical walls.

Figs. 8h and 8i show a syringe head 100 prior to piercing the seal 90 in order to allow, for example, an endoscopist to administer fluid via the endoscopic channel.

Figs. 8j and 8k demonstrate how a biopsy forcep 110 is able to pierce the seal 90 in order to allow, for example, an endoscopist to gather a tissue sample.

Although the invention has been described with reference to specific examples, it will be appreciated by persons skilled in the art that the invention may be embodied in many other forms.

Claims

Claims:

1. A channel seal for an endoscope, the channel seal comprising: a body with an internal passage therethrough; and an integrally formed frangible member occluding the passage.

2. The seal as claimed in claim 1, wherein the frangible member is adapted to rupture in response to force above a predetermined level being applied thereto.

3. The seal as claimed in claim 2, wherein the predetermined level of force required to rupture the member is approximately equal to that generated by an adult person pushing an endoscope ancillary instrument.

4. The seal as claimed in claim 1, 2 or 3, wherein the frangible member is sufficiently resilient to substantially occlude the passage after rupturing, in the absence of any objects therein.

5. The seal as claimed in claim 4, wherein the frangible member is sufficiently resilient to substantially occlude the passage after rupturing, in the absence of any objects therein, in the presence of a pressure differential across the frangible membrane of about 3 to 9 Psi.

6. The seal as claimed in any one of the preceding claims, wherein the frangible member is of constant thickness across the passage.

7. The seal as claimed in any one of claims 1 to 5, wherein the frangible member includes a region of weakness therein.

8. The seal as claimed in claim 7, wherein the region of weakness is in the form of a reduced thickness portion.

9. The seal as claimed in claim 8, wherein the reduced thickness portion is a diametric depression across one or both sides of the frangible member

10. The seal as claimed in claim 8, wherein the reduced thickness portion is two aligned diametric depressions, one on either side of the frangible member.

11. The seal as claimed in claim 8, wherein the reduced thickness portion is circular.

12. The seal as claimed in claim 11, wherein the circular reduced thickness portion is bounded by two frusto-conical portions.

13. The seal as claimed in any one of claims 8 to 12, wherein the thickness of the reduced thickness portion is about 0.2 mm.

14. The seal as claimed in claim 13, wherein the thickness of the remainder of the frangible member is about 1.6 mm.

15. A channel seal for an endoscope, the channel seal comprising: a body with an internal passage therethrough; and an integrally formed member occluding the passage, wherein the occluding member has a region of weakness formed therein.

16. The seal as claimed in claim 15, wherein the occluding member is adapted to rupture in response to force above a predetermined level being applied thereto.

17. The seal as claimed in claim 16, wherein the predetermined level of force required to rupture the member is approximately equal to that generated by an adult person pushing an endoscope ancillary instrument.

18. The seal as claimed in claim 15, 16 or 17, wherein the body also includes a first internal recess adapted to engage an external flange of a first corresponding size on the proximal end of an endoscopic channel.

19. The seal as claimed in claim 18, wherein the body also includes a second internal recess, of differing size to the first internal channel, adapted to engage an external flange of a second corresponding size on the proximal end of an endoscopic channel.

20. The seal as claimed in claim 19, wherein the frangible member is longitudinally positioned between the first and the second internal recesses.

21. The seal as claimed in any one of claims 15 to 20, wherein the body includes an integrally formed plug which, upon insertion into an end of the body, is adapted to substantially seal the passage.

22. The seal as claimed in any one of claims 15 to 20, wherein the body includes an integrally formed plug which, upon insertion into either end of the body, is adapted to substantially seal the passage.

23. The seal as claimed in claim 21 or 22, wherein the body includes a flexible arm integrally formed between the body and the plug.

24. The seal as claimed in claim 21, 22 or 23, wherein the plug also includes: an internal passage therethrough; and an integrally formed frangible member occluding the plug passage.

25. The seal as claimed in claim 24, wherein the plug frangible member is of constant thickness across the passage.

26. The seal as claimed in claim 24, wherein the plug frangible member includes a region of weakness therein.

27. The seal as claimed in claim 26, wherein the plug region of weakness is in the form of a reduced thickness portion.

28. The seal as claimed in claim 27, wherein the plug reduced thickness portion is a diametric depression across one or both sides of the frangible member.

29. The seal as claimed in claim 28, wherein the thickness of the plug reduced thickness portion is about 0.2 mm.

30. The seal as claimed in claim 29, wherein the thickness of the remainder of the plug frangible member is about 1.6 mm.

31. The seal as claimed in any one of the preceding claims, wherein the seal is moulded from at least one polymer elastomer or at least one polymer/plasticiser combination.

32. A method of moulding a channel seal for an endoscope, the method comprising moulding a channel seal body with an internal passage therethrough and an integrally formed frangible member occluding the passage.

33. The method as claimed in claim 32, further including moulding the frangible member with a constant thickness across the passage.

34. The method as claimed in claim 32, further including moulding the frangible member with a region of weakness therein.

35. The method as claimed in claim 34, wherein the region of weakness is in the form of a reduced thickness portion.

36. The method as claimed in claim 35, wherein the reduced thickness portion is in the form of a diametric depression across one or both sides of the frangible member.

37. The method as claimed in claim 35, wherein the reduced thickness portion is in the form of two aligned diametric depressions, each across one side of the frangible member respectively.

38. The method as claimed in claim 35, wherein the reduced thickness portion is circular.

39. The method as claimed in claim 38, wherein the circular reduced thickness portion is bounded by two frusto-conical portions.

40. The method as claimed in any one of claims 35 to 39, wherein the thickness of the reduced thickness portion is about 0.2 mm.

41. The method as claimed in claim 40, wherein the thickness of the remainder of the frangible member is about 1.6 mm.

42. The method as claimed in claim any one of claims 32 to 41, further including moulding an integrally formed plug with the channel seal which, upon insertion into an end of the body, is adapted to substantially seal the passage.

43. The method as claimed in any one of claims 32 to 41, further including moulding an integrally formed plug with the channel seal which, upon insertion into either end of the body, is adapted to substantially seal the passage.

44. The method as claimed in claim 42 or 43, further including moulding an integrally formed flexible arm between the body and the plug.

45. The method as claimed in any one of claims 32 to 44, further including moulding the channel seal from at least one polymer elastomer or at least one polymer/plasticiser combination.