Sterilizing instrument

Details Sterilizing instrument Sterilizing instrument

2002-02-28

2004-08-10

Truong, Kevin T. (Department: 3731)

Surgery

Instruments

Suture, ligature, elastic band or clip applier

Reexamination Certificate

active

06773439

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a surgical instrument for sterilizing a patient, and especially to an instrument adapted to cut and occlude the Fallopian tubes, or oviducts, of a female patient.
BACKGROUND OF THE INVENTION
Much misery is caused by unwanted pregnancy. It presents the unpalatable alternatives of abortion with its emotional turmoil and social cost or, if the parent(s) are unwilling to terminate the pregnancy for religious or other reasons, the imposition of an unexpected child. The life of the child and its parents can be ruined, with the child suffering from a lack of love and support and the relationship between its parents coming under strain due to emotional and financial problems. These problems can be all the worse if the child is physically or mentally handicapped.
There are also medical reasons for avoiding unwanted pregnancy. The parents'genetic makeup may predispose a child to be physically or mentally handicapped, or the mother may harbour infection such as HIV that might be passed on to the child. The parent(s) may be mentally or physically unable to look after a child, or the mother may be so ill that continuation or even termination of a pregnancy presents a serious risk to her.
For all of these reasons, reliable birth control or family planning is one of the major objectives of medical science. A large part of this effort relates to sterilization, which is now the most commonly-used method of family planning in the world. In 1990, for example, more than 190 million married women of reproductive age relied on sterilization of themselves or their partners for contraception. This represents 22% of married women of reproductive age in developing countries and 11% in developed countries. Indeed, in the US, sterilization has become the most commonly used method of contraception among married couples. Sterilization is intended to be permanent: reversal surgery is available, but it can be difficult and can never guarantee to restore fertility.
In the case of a female, sterilization generally involves occluding and optionally also cutting the Fallopian tubes, or oviducts, that convey ova from the ovaries to the cavity of the uterus. The term oviducts will be used hereinafter for convenience. Briefly, the oviducts are situated in the free margin of the broad ligament that extends outwardly in a layered web-like manner from the sides of the uterus. The part of the broad ligament that supports the oviducts is known as the mesosalpinx. The layers of the broad ligament also embrace the two round ligaments that extend forwardly, outwardly and downwardly from the uterus.
There are several sterilization techniques involving occlusion of the oviducts, notably:
(i) Ligation with partial salpingectomy, in which the oviducts are tied with suture material and cut, most commonly by tying off a small loop of the oviduct and then cutting through the loop. This procedure is performed through an abdominal incision and so is most often used when sterilization procedures are performed postpartum or if laparoscopic surgery is not possible because of obesity or inaccessibility, for example due to pelvic adhesions.
(ii) Coagulation or cautery, in which electrical current is used to block or divide the oviducts. This procedure is effective, but brings a risk of thermal injury to nearby tissues such as so-called bowel burn, as discussed by Thompson et al in
Obstetrics
&
Gynaecology
May 1973, Vol. 41, No. 5, at page 669 et seq.
(iii) The application of a silicone or Silastic band such as a Falope ring in which, using a special applicator, the surgeon forms a loop in the oviduct and stretches a small silicone ring to slip it over the loop. The ring thus compresses and occludes the oviduct at the neck of the loop, strangling the portion of oviduct that forms the loop. The procedure is discussed at length by Levinson et al in
Obstetrics
&
Gynaecology
October 1976, Vol. 48, No. 4, at page 494 et seq., and by Yoon et al in
The Journal of Reproductive Medicine
Jan. 15, 1977, Vol. 127, No. 2 at page 109 et seq., in the
American Journal of Obstetrics
&
Gynaecology
August 1979, Vol. 23, No. 2 at page 76 et seq., and in
The Journal of Reproductive Medicine
August 1979, Vol. 23, No. 2 at page 76 et seq.
(iv) The application of a clip to the isthmic part of the oviduct to compress and thus occlude the oviduct, most notably the Hulka-Clemens or Hulka spring clip most commonly used in the US and the Filshie clip most commonly used in Europe. Initial experience of the Hulka clip is discussed by Hulka et al in the
American Journal of Obstetrics & Gynaecology
, Jul. 1, 1973, Vol. 116, No. 5 at page 715 et seq. Similar experience of the Filshie clip is discussed by Filshie et al in the
British Journal of Obstetrics
&
Gynaecology
June 1981, Vol. 88, pp. 655-662. There are other types of occlusive clip, such as the recently-introduced Cambridge clip.
Apart from ligation with partial salpingectomy, the above procedures are apt to be performed laparoscopically. Laparoscopic female sterilization is popular because of its short recovery time and relatively low complication rate.
As female sterilization is invariably performed upon those for whom pregnancy is deemed to be undesirable or unsafe, it follows that the probable consequence of a failed sterilization—an unexpected pregnancy—is all the more damaging. Failed sterilization also involves an increased risk of ectopic pregnancy, which presents a very direct threat to the patient's health: as many as one third of sterilization failures involve ectopic pregnancy. Unsurprisingly, therefore, failed sterilization is one of the major reasons for law suits against gynaecologists and obstetricians, in some countries accounting for one third of all such cases.
The prospect of damages and legal costs coupled with the increasingly hostile climate of litigation for medical negligence adds to the stress of the physician's life and escalates the cost of medical negligence insurance. Nor should the professional impact of a medical negligence claim be forgotten: an accusation of negligence based upon a failed sterilization can be as damaging for the physician's professional career as it is for the lives of those most directly affected by an unwanted pregnancy.
Sterilization can fail for various reasons, but where an occlusive device is employed, failure can usually be attributed to improper application of the occlusive device. A clip should be applied so that it completely compresses and occludes the oviduct, for which purpose the clip should be placed on the distal isthmus end of the oviduct (3 cm from the cornual end of the uterus) at precisely 90° to the longitudinal axis of the oviduct, with one side of the oviduct lying against the hinge of the clip and the clip embracing part of the mesosalpinx on the other side of the oviduct. If these objectives are not fully met, the clip might not properly occlude the oviduct. Analogous problems are encountered with Falope rings, as explained in the abovementioned 1979 paper by Yoon et al in
The Journal of Reproductive Medicine
. It is even possible for the clip or ring to be applied to the wrong structure entirely, for example to the round ligament that can quite easily be confused with the oviduct during laparoscopic procedures.
Both clips and rings can fail if the oviducts are thicker than normal for whatever reason. Clips may be unable to cross the full thickness of the oviduct, and the loop of oviduct formed by a ring applicator may be severed by the force used to pull the loop into the applicator. Rings also fail sometimes because the applicator does not form a proper loop in the oviduct, especially when the loop is too small. In that instance, any stretching movement of the oviduct will cause the ring to slip.
Not all failed sterilizations are the physician's fault. Clips or rings can slip from an oviduct even if they are properly applied, although this is a difficult situation to verify as a misplaced clip or ring could, of course, merely indicate failur

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