Surgery – Instruments – Electrical application
Reexamination Certificate
2001-08-23
2004-05-04
Rollins, Rosiland (Department: 3739)
Surgery
Instruments
Electrical application
C606S041000, C606S045000, C606S049000, C600S564000
Reexamination Certificate
active
06730085
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to the surgical biopsy excision of tissues, particularly but not exclusively the excision of abnormal lining in the uterine cervix.
Cancer of the uterine cervix, or cervical cancer, usually progresses slowly over an extended period from the first appearance of pre-cancerous abnormalities. With today's sophisticated screening programs involving regular smear testing, colposcopy and so on, this gradual progression presents an opportunity for many patients entirely to avoid cervical cancer if they can benefit from preventative intervention. Even for those who do not, there is a good prognosis if the cancer is detected and treated early enough.
Before malignant cells are found, the tissues of the cervix go through changes in which abnormal cells begin to appear, initially on the epithelial tissue on the surface of the cervix. This precancerous condition is known as dysplasia or cervical intraepithelial neoplasia (CIN).
CIN does not directly infer cancer but refers to a spectrum of abnormality ranging from mild dysplasia, that may regress without intervention, to severe dysplasia that may extend to carcinoma-in-situ, the cancer initially being localised to the intraepithelial tissue or superficial layer of the cervix. If left untreated, the cancer cells will start to grow and spread more deeply into the cervix and to surrounding areas, necessitating hysterectomy at best and, of course, threatening the patient's life.
If left untreated, around 30% to 50% of CIN conditions may progress to invasive cancer. Clearly, detection and treatment of CIN is essential to avoid the possible development of cervical cancer.
CIN is a lesion of abnormal cells typically associated with the Human Papilloma Virus (HPV). When HPV is contracted, it infects the cells of the transformation zone of the cervix where the cells of the cervix actively divide and grow. As those cells grow and mature, they are pushed to the surface as new cells are produced and the older, outside cells die and are shed. When the virus infects the cells and then becomes active, abnormal cells begin to be produced in the transformation zone and a lesion develops in the epithelial tissue at the surface of the cervix.
Removal of the lesion is an effective treatment for CIN. Although HPV remains once the CIN lesion is removed, the rate of recurrence of CIN is quite low since the removal of the transformation zone eliminates the tissue most susceptible to CIN.
Lesioned or dysplastic cells may be removed by cauterisation, cryosurgery or laser surgery. Cauterisation uses heat, electricity or chemicals to burn the abnormal tissue off the cervix. Cryosurgery freezes the cells and laser surgery destroys the cells with a laser beam. Various specific techniques include cryocautery, cold coagulation, large loop excision of the transformation zone, diathermy, needle excision of the transformation zone, cold knife cone biopsy, laser ablation, laser cone and a combination of cutting diathermy cones.
A common cervical excision procedure employs loop electrosurgery, sometimes called the Loop Electrosurgical Excision Procedure or LEEP. LEEP uses a thin wire loop electrode connected to an electrosurgical generator that emits an electric current to cut away affected tissue. A low voltage and relatively high frequency electric current is emitted from the loop into the tissue cells in the immediate area of the loop wire. Consequently, the cells heat rapidly, generating steam that causes the cells to burst microscopically and thus divides the tissue as the wire moves through the tissue. The wire is typically swept across the projecting neck of the cervix, or ectocervix, thereby removing a thin annular slice of tissue.
Unlike most other treatment methods, particularly ablative methods such as laser surgery, LEEP allows the physician to have the excised specimen analysed by a pathology laboratory. This allows for more accurate assessment of the abnormal tissue, which will confirm either that the lesion has been completely removed with the biopsy sample or, if it has not, what further treatment may be necessary.
The entire LEEP procedure usually takes less than fifteen minutes and is generally very effective and well received by patients. However, LEEP has its complications.
Because LEEP utilises electric current, burns to the vagina and other surrounding tissue may occur; such injury will cause unnecessary discomfort during and after the procedure, and may substantially lengthen the patient's recovery period.
Another problem of inaccurate use of a loop electrode is that the sample of tissue obtained may vary in amount and definition. LEEP is particularly prone to producing fragmented and burnt biopsy samples if it is necessary to make multiple passes of the loop, which reduces the accuracy of diagnosis. Multiple passes are particularly needed where, as is common, a lesion extends into the endocervical canal.
Incomplete removal of the lesion when excising the transformation zone is another, much larger potential risk, since this can only worsen the patient's long-term prognosis and will require further procedures to remove the remaining abnormal cells. This puts the patient through further unpleasant and emotionally draining treatment. The converse risk is the removal of too much tissue, which may result in cervical stenosis, an incompetent cervix, and/or sterility.
The underlying problem of LEEP is that the loop electrode is generally on the distal end of a long handle for which there is no guiding support in use. Once energised, the loop will instantly cut into and burn any tissue with which it comes into contact and so accurate positioning is critical both upon encountering the cervix and during excision of cervical tissue. Not only must the head of the instrument be placed exactly where it is needed before excision starts, but also the movement of the wire must be carefully controlled during its excising pass across the cervix. The lack of support makes it difficult for even an experienced physician to achieve an accurate cut; the problem is worse if the operating physician is inexperienced, particularly where visibility of the lesion is poor.
The inherent lack of stability of the loop electrode is exacerbated because the electrode itself can move in relation to the handle under the influence of drag as the electrode passes through the cervical tissue. This compounds the difficulty of knowing exactly where the electrode is at all times, and thus adds to the difficulty of producing an accurate cut.
Owing to the problems outlined above, there have been attempts to modify the standard loop cervical biopsy device. The most notable modification is described in International Patent Application No. PCT/US95/01262 to Fischer, published as WO95/20922.
The Fischer instrument described in WO95/20922 has an elongated insulated body member with an endocervical portion at the distal end, a contact portion at the proximal end and a vaginal portion in between. An insulated stop arm extends at right angles to the body member from the junction of the endocervical and vaginal portions. A wire electrode extends diagonally between the stop arm and the endocervical portion.
The Fischer instrument is sold by a US company, Apple Medical Corporation. It has come to be known among physicians as the Fischer cone biopsy device or simply as the Fischer cone, which term will be used hereafter for brevity.
In use, the Fischer cone is connected by means of the contact portion to an electrosurgical generator such as a blend cutting diathermy machine. The instrument is then inserted into the cervix through the vaginal canal, the vaginal canal being held open by a duckbill speculum as is well known in the art. The endocervical portion is aimed into the cervical canal to gain support for the distal end of the instrument, whereupon the wire is energised through the contact portion and conductor means within the insulated body.
When the energised wire contacts the cervical tissue at the ectocervix, a current passes thro
Abrahams Yusuf
George Samuel
Lerner David Littenberg Krumholz & Mentlik LLP
Rollins Rosiland
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