Device to facilitate multiDle polypectomy, including a system for retrieval of all polyps
Background
Our invention solves the problem of how to retrieve large polyps removed from the colon such that the endoscopist is confident important pathological samples will be retrieved from evacuated stool and such that the colonoscopy and polypectomy procedure is not unduly lengthened or repeated for the patient.
Colonoscopy is visualisation (via digital viewing equipment) of the large bowel by gradual and careful insertion of a fibreoptic camera (called a colonoscope which is 1.2 m long) into the anus. This is standard equipment used in hospital endoscopy units.
A polyp is a growth from the bowel lining. Polyps should be examined under a microscope for the potential to be cancer. The histological classification of the polyp affects future clinical management of the patient determining further colonoscopies or even major surgery.
Whenever polyps are visualised they require removal (polypectomy). Polypectomy is done using devices inserted through a biopsy channel built into the colonoscope. A snare device has a loop that can be opened and closed over the polyp. By connection to an electrical current (diathermy) the tightened loop heats the tissue sufficiently to cause the polyp to drop off the bowel lining.
Small polyps (less than 5mm diameter) are retrieved by being aspirated via the suction port of the colonoscope.
Large polyps (5mm to perhaps 5cm diameter) have to be left to pass naturally through the bowel mixed with stool in subsequent bowel movements. The evacuated stool has to be carefully examined for the polyp. The polyp has to be extracted from the stool and put into a laboratory sample pot.
This is an unreliable method for retrieval as the patient (or carer or nursing staff) may be reluctant to thoroughly inspect the stool and manually retrieve the polyp. Also the polyp may not be easily distinguishable within the stool.
If a patient has only one polyp this can be brought out with the snare tightened around it as the colonscope is withdrawn. However it is common that a patient may have multiple polyps. It becomes a prolonged and uncomfortable procedure to insert the colonoscope, withdraw it with the removed polyp, then reintroduce the colonoscope for every subsequent polyp.
Statement of invention
Our invention enables the endoscopist to enclose the first snared polyp in a casing (or net) that is brightly coloured (and may also be metallic). This encased polyp is then left in the bowel whilst the endoscopist moves on to the next polyp. This is similarly encased. The endoscopist can then move on to subsequent polyps.
After the procedure the patient would be asked to pass stool into a commode (either at home or on the ward). Stool passed over the next few days would be examined for the encased polyps which would be easily identifiable due to the bright colouring of the encasing material. Also if metallic, a metal detector passed over the stool would alert the person retrieving polyps to the locations or indeed presence of the polyps. Therefore the task of retrieving polyps from evacuated stool would be more successful, easier, speedier and guided by the metal detector. This would compare to a psychologically weary search prodding stool in the hope of finding pinkish-brown tissue often smaller than 1cm diameter; indistinct and tiny polyps in a mass of stool.
Adva ntages * Straightforward. The method of encasing the snared polyp is using a device inserted through the existing biopsy channel of the colonoscope. Therefore it is compatible with existing stock of colonoscopies in endoscopy units. This avoids expensive investment in new colonoscopies.
* The novel aspect of our invention is the detachable nature of the encasement such that the encased polyp is left free in the bowel lumen. A trigger mechanism operated by the endoscopist or assistant would release the encased polyp from the >1.2 m long wire used to pass the encasement through the 1.2 m length of colonoscope.
* Peace of mind for the endoscopist. If a polyp looks malignant there will be considerable stress for the endoscopist who will be making great efforts to retrieve the polyp so that it can be sent to the laboratory. That the polyp is retrieved is imperative for the patient. A diagnosis of a cancer or potential cancer in a polyp is a crucial diagnosis. It is important to have a technique that allows for leaving the detached encased polyp in the bowel yet still gives the endoscopist the mental confidence to know there is every likelihood of that polyp being retrieved from evacuated stool later.
* Cost. Our device would be of similar cost to existing devices (such as the snare). It would therefore be a relatively cheap piece of endoscopy equipment.
* Single use. Each polyp encasement unit would be single use only. Therefore no part of our system would risk passing infections between patients.
* Time saving. At present the colonoscopy procedure can be prolonged for the patient due to efforts made to retrieve polyps during the procedure. Reinsertion of the colonoscope to snare and retrieve multiple polyps involves increasing discomfort for the patient. Our invention does not require the colonoscope to be inserted more than once.
* Reduce medications. A prolonged colonscopy and polypectomy procedure may require regular interval dosage of medications in order to alleviate discomfort for the patient. Our system might reduce the use of medications and thus reduce the side effect risks (respiratory depression, low blood pressure, vomiting).
* Improved retrieval rate. The detachable brightly coloured net encasing the polyp would improve retrieval rate from evacuated stool. Without brightly coloured encasement the polyp is of similar colour to stool and usually small for visualisation by the naked eye.
* Polyp retrieval more palatable to the person retrieving polyps. By making the polyps easier to identify the job of finding the polyps would be less unpleasant.
* Knowing where to prod the stool to find the polyp. By using a metal detector the location of any polyp within the stool could be easily determined.
* Improved quality of sample for the laboratory. By encasing the removed polyp the laboratory would receive the entire polyp. At present sometimes polyps are broken up so that they can be retrieved more easily or at least one part of a polyp is retrieved. By sending the entire whole, undamaged polyp to the laboratory, analysis for cancer or pre-cancer will be more accurate and comprehensive.
* Localisation of removed polyp to where it originated in the bowel. By using varied coloured encasement it could be recorded on the endoscopy report which coloured encasement contained a polyp removed from which location in the bowel. This is important in clinical management as should a further procedure or surgery be required the unhealthy portion of bowel originating the polyp would be known accurately. Further procedures would then be targeted to the correct area of bowel. At present there is no means to know which particular polyp came from which location.
* Suitable for small (<5mm) polyps as well. Although aimed at retrieval of large polyps that cannot be aspirated, our device could be used for small polyps as well as encasing them may be less time-consuming than aspirating them via the suction port. Avoiding aspirating them via the suction port removes the risk of blocking the suction port by the poiyp which then can undermine the success of the remainder of the colonoscopy (as the suction port is vital to achieve clear views and remove excessive gases that accumulate and can distend the bowel dangerously).
Introduction to drawings
An example of the invention will be described with reference to the accompanying drawings, figures 1 to 6 which illustrate views obtained via the colonoscope at the time of colonoscopy.
Figure 1 shows a polyp (a) growing from the bowel lining (b).
Figure 2 shows the poiyp snared (c).
Figure 3 shows the poiyp has been removed from the bowel by application of heating current to the snare, and is lying loose on the bowel lining.
Figure 4 shows the polyp is covered by encasing net (e).
Figure 5 shows the encasing net has been tightened and closed around polyp. Then it has been detached from the wire (d) traversing the length of the colonoscope (1) and connecting to the trigger device (g). The trigger device can be manipulated to open and close the encasement and also to initiate the release mechanism, so that the encasement detaches and becomes free in the bowel.
Figure 6 shows multiple encased polyps passed out of bowel with stool (h). These are readily distinguishable from stool by colour. If buried inside stool therefore presence can be detected by a metal detector.
Detailed description
Our invention can be made by connecting an encasement pouch to a purse-string closure mechanism. This is connected via a greater than 1.2 m length of wire (long enough to traverse the length of the colonoscope) to a handheld trigger mechanism that can close the purse-string around the free polyp and then detach the encased polyp such that it is again free in the lumen of the bowel. The polyp is now encased in a material that may be brightly coloured and/or metallic. This procedure is repeated for further polyps. The patient can then leave the endoscopy room (having had a procedure that has not been unduly protracted and without the colonscope having been required to be inserted more than once). Multiple polyps can be encased on withdrawal of the colonscope after the initial insertion. Later the patient is asked to pass stool into a commode. The encased polyps can be localised by the metal detector and easily visualised by the bright colour of the encasement. The likelihood of all polyps being retrieved has been increased.