US3312214A - Intra-uterine device - Google Patents

Description

April 4, 1967 c. L. BURDICK 3,312,214

INTRA-UTERINE DEVICE Filed June 6, 1966 2 Sheets-Shet 1,

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BY 08mg April 4, 1967 CJLJBURDICK 1 INTRA-UTERINE DEVICE Filed June 6, 1966 2 Sheets-Sheet 2 g m I 1/ m I v INVENTOR. Mfl/PMS mmaafia/cx United States Patent 3,312,214 lNTRA-UTERINE DEVICE Charles Lalor Burdick, Christiana Hundred, Del. (4400 Lancaster Pike, Wilmington, Del. 19805) Filed June 6, 1966, Ser. No. 555,503 10 Claims. (Cl. 128-130) This invention relates to intra-uterine devices and'more particularly to a new intra-uterine device having three continuous loops.

Early in this century, Grafenberg made medical use of a simple gold or silver ring inserted into the uterine cavity of a woman to prevent pregnancies. Although generally successful, the ring fell into disrepute because in some cases the woman experienced pain or infection, while in others pregnancies occurred and in general the medical profession inveighed extensively against the prac tice of inserting anything into the uterus.

After 1950, there was a resurgence of research in the field of intra-uterine devices resulting in much greater success with fewer complications than had been achieved by Grafenberg. Among the best known of the present devices are the Margulies spiral, the Birnberg how, the Lippes loop and various forms of rings or coils.

The types of intra-uterine devices mentioned above give pregnancy rates on large scale tests with fertile women ranging from 1.5 to or more per 100 Womanyears of exposure. This compares favorably with the best alternative methods of contraception and is, of course, much better than no care at all.

There are, however, many deficiencies with the presently available intra-uterine devices and some of these deficiencies are the incidence of menstrual troubles, unusual bleeding and more seriously a high rate of spontaneous expulsion, either noticed or unnoticed. Prior devices which helped alleviate the menstural trouble and unusual bleeding resulted in increased expulsion and in higher pregnancy rates.

The rate of spontaneous expulsion varies considerably between the various types of intra-uterine devices. The normal uterus undergoes rhythmic muscular contractions or peristalsis more or less steadily and continuously and of greater or less extent. The rates of expulsion will vary with this and with the degree of tightness of the cervix opening and, of course, with the design of the device itself.

Although statistical data is at present scant on the problems encountered with intra-uterine devices, the National Committee on Maternal Health has recently compiled most of the available data into one comprehensive compilation which appeared on page 178 of the April 1966, issue of Good Housekeeping Magazine. This compilation was based on a cooperative study of forty-three medical institutions and private practices in the United States and Puerto Rico and involved first insertions and first year use in 11,222 women. The results are presented below in the form of percentages per 100 woman-years of use.

Loop Spiral Bow Ring Pregnancies 2. 4 1. 8 5. 7 7. 5 Expulsions 9. 9 22. 5 2. 4 18. 2 Removals 15. 6 25. 7 11. 1 10. 2 Pelvic inflammatory disease 1. 7 3. 9 2. 2 3. 2

Percent Loop 29.6 Spiral 53.9 Bow 21.4 Ring 39.1

It can thus be appreciated that there is a need for an improved intra-uterine device which exhibits a low pregnancy rate and yet which minimizes the other deficiencies set out above.

Up to the present time there have been no systematic studies of ways to conform intra-uterine devices to the contours of a human uterine cavity. It would seem that the design characteristics of such devices should take into consideration a knowledge of the uterine morphology.

As pointed out by Davis and Israel in Uterine Cavity Measurements in Relation to Design of Intra-Uterine Contraceptive Devices," Infra-Uterine Conception, Proceedings of the Second International Conference, October 1964, New York City, at page 135, An ideal intrauterine device should combine two mechanically contradictory characteristics: ease of insertion and resistance to expulsion. None of the intra-uterine devices currently in use completely satisfy these criteria. In addition, little attention has been given to design elements to take advantage of uterine musculature and peristalsis and to facilitate the downward passage of the ovum with minimum contact with the uterine cavity walls. The conventional design of a loop sets up an actual series of barriers tending to impede a fertilized ovums downward transit toward the cervical exit.

According to this invention, there is provided an intrauterine device generally in the shapeof a trefoil which comprises an inert endless material in the shape of three continuous freely-movable adjacently-positioned loops; the loops being inter-connected in such a manner that the two terminating portions of each loop continue smoothly into the terminating portions of the adjacent loops. The intra-uterine device is capable of being deformed by the application of a small amount of force and yet is sufliciently elastic to return substantially to its original shape when the force is removed.

The term freely-moving, as used in this specification, means that when the device is held in a horizontal position, each loop is independently capable of motion in a vertical, horizontal, or rotary direction, or in any combination of these. The term adjacently-positioned means that each loop is adjacent to both of the other loops.

A method of preventing pregnancy using an intrauterine device as described above comprises the following steps:

(1) Deforming and inserting this intra-uterine device into the open end of a cannula which can be passed through the cervical canal,

(2) Inserting the open end of, the cannula through the cervical canal into the uterine cavity, and

(3) Expelling the intra-uterine device from the cannula into the uterine cavity whereby the intra-uterine device returns substantially to its original shape and becomes lodged within the uterine cavity.

The intra-uterine device of this invention has the advantage of having no free ends or cuspate forms which tend to pierce the delicate uterine wall upon insertion of the prior devices or upon the prior devices shifting position after insertion. Another advantage is that the geometrical design of the new intra-uterine device makes it far less susceptible to expulsion from the uterus. A still further advantage lies in the continuous shape of this intra-uterine device which makes it far more adaptable to the uterine cavity than the prior art devices. A ,still further advantage of this device is that the three loops provide ready channels for unimpeded transit of the ovum or blastocyst through the main uterine cavity toward the cervical exit. A still further advantage lies in the ease of forming the intra-uterine device of this invention in a variety of sizes and shapes within the basic configuration of three continuous loops which makes it readily adaptable to insertion in a wide range of uterine cavities.

The invention will be better understood by reference to the drawings.

FIGURE 1 is a plan view of inert endless material in the shape of an annulus suitable for forming into the intra-uterine device of this invention.

FIGURE 2 is a perspective view of a template with three mandrels suitable for forming the intra-uterine device of this invention.

FIGURES 3 through 8 are plan views of some of the varieties of the intra-uterine device of this invention.

FIGURE 9 is a plan view of a cannula suitable for inserting the intra-uterine device of this invention.

FIGURE 10 is a plan view showing how the intrauterine device of this invention is inserted.

FIGURE 11 is a plan view of a human uterus and cervical canal with an intra-uterine device of this invention properly lodged in the uterine cavity.

FIGURE 12 is a cross-sectional view of an intrauterine device of this invention lodged within the uterine cavity.

As can be seen from FIGURES 3 through 8, the trefoil intra-uterine device of this invention can have a variety of shapes and sizes. The geometrical feature characteristic of all of the shapes is that each has three continuous loops and no free ends. Within the basic configuration, it is possible to have species of the trefoil intra-uterine device wherein all of the loops are crossed, none of the loops are crossed, or wherein any combination of crossed loops and uncrossed loops in between these limits is present. For example, FIG. 3 illustrates an embodiment with three crossed loops, FIG. 6 illustrates an embodiment with the two upper loops crossed and a lower loop which is uncrossed, and FIG. 8 illustrates an embodiment with two upper uncrossed loops and a lower crossed loop.

The intra-uterine device of this invention can be manufactured by starting with an inert endless material approximately circular in cross-section in the form of an annulus 2 as is shown in FIGURE 1. The annulus is fitted to the template by bending and twisting it around the mandrels 12 until the desired shape is obtained. The .inert material is heat set on the template so that it will retain its shape after removal from the mandrels. Heat setting is achieved by heating the material to an elevated temperature below the melting point and then allowing the material to cool to room temperature. It is sometimes desirable to attach a tail 4 to the ring so that when the device is in place in the uterine cavity, the tail extends into the womans vagina and she can check to see that the device is still in place by feeling for the tail. A tall can be made from any type of flaccid, strong, inert filament such as nylon or linear polyethylene.

Any inert endless material can be used for this intrauterine device provided it is physiologically inert and provided it is capable of being deformed by the application of a small amount of force and yet is sufliciently elastic to allow the intra-uterine device to return substantially to its original shape when the force is removed. The device only returns substantially to its original shape because it adapts itself to the configuration of the uterine cavity thereby causing, in some cases, small deformation of the device. By a small amount of force is meant the amount of force which a person can exert by squeezing his thumb and forefinger together. When this force is exerted on the intra-uterine device, the device is pinched into a flat, double-looped shape 52 which is easily insertable into the flexible end of the cannula 44 of FIGURE 9. Prior threading of the tail 4 through the cannula, or a separate thread looped through the device, can assist materially in drawing the device into the cannula.

Another helpful means for this is that tail 4, in addition to being fastened at point 27, may have a suitable extension which connects with the cross member between loops 30 and 32. This extension may provide also an additional channel facilitating exit of the ovum from the uterus.

The inert endless material can be a single filament or multifilament. Any physiologically inert material having the required elasticity is suitable and some useful examples include polymers of propylene, ethylene, tetrafluoroethylene, acrylic acid, methacrylic acid, terephthalic acid, and esters of acrylic, methacrylic, and terephthalic acids, acrylonitrile, methacrylonitrile, vinyl acetate, butadiene, styrene and interpolymers of these. Other useful materials include any of the well known polyamide compounds such as poly(caproamide) poly(metaphenylene isophthalamide), poly(hexamethylene sebacamide), and poly(hexamethylene) ,adipamide. Natural substances which meet the inertness and elasticity standards such as cat gut and silk worm gut are useful. Silicone rubbers are also useful.

A radiation opaque material such as barium sulfate can be added to the inert endless material to make possible the determination by radiology of the exact location of the intra-uterine device after insertion.

The cross-section of the inert annular material is not subject to being defined in terms of exact dimensions. In general, it depends upon the modulus of the material used. There are other factors to be considered, of course,

in selecting a material of proper cross-section and one of these is the thickness of the device desired which again depends upon the uterine dimensions and size of the cervical opening. For the normal parous uterus, one would usually use a device measuring about 32 millimeters across outside-to-outside of the upper loops and about 30 millimeters outside-to-outside from top to bottom. The cross-section of the inert endless material itself can range from about 0.7 to 2.20 millimeters in diameter, or, if of multifilament, can be conveniently made of ten to twelve turns of a filament of about 0.2 to 0.5 millimeter in diameter. When the inert endless material is not exactly circular in shape, these diameter measurements apply to the major diameter.

A convenient shape for the cross-section of the inert endless material is approximately circular. The term approximately circular is meant to include for purposes of this invention shapes which are circular, elliptical, oval or any other cross-sectional shape which is bounded by smooth simple closed curves. Any cross-sectional shape, however, is sufficient.

In general, the interior shape of a human parous uterus 20 can best be described as a flattened cavity with upper and lower walls or folds substantially in contact with each other and with edges approximating an isoceles triangle standing upon its apex with the two uterine horns 23 and 25 located at the opposite ends of the base. As is shown in FIGURES 10 and 11, the three looped intrauterine device of this invention has a natural form to approximate this shape thereby filling almost entirely the uterine cavity 21. Although it is not known exactly how intra-uterine devices prevent pregnancy, the general belief is that filling a greater percentage of the uterine cavity will produce better results.

As has already been pointed out, the uterine cavity is normally fiat. With the three looped intra-uterine device of this invention, a preferred separation of the uterine cavity walls can be achieved by selecting an inert endless material of proper diameter and then by fabricating the loops in any of the previously described variations to give a proper separation between the anterior 22 and posterior 24 walls of the uterus without stretching the uterus itself to an extent which would be painful to the woman.

As has already been pointed out, peristalsis, the continual contraction and expansion of the fundus muscle located at the top of the human uterus 26 is synchrony with the other musculature is a main cause of the expulsion of the present intra-uterine devices. As can be seen from FIGURE 11, the upper configuration of the three looped intra-uterine device has opposite loops 30 and 32 connected across by a depressed flexible curvature 28 which gives little opportunity for the heavy musculature in the central portion of the upper uterine wall to press downward against the device. What appears to happen is that the resultant of the forces tends to push the two upper loops of the device further into their corresponding uterine horn cavities and to expand the lower loop 27 horizontally, all of whichtends to resist expulsion and to hold the device in place. An important feature of this device, then, is that the lower loop 27 be broad enough at its base to resist the initiation of expulsion due to this peristalsis or to any other undesired expelling force.

The preferred embodiment of the invention is a three looped intra-uterine device which is constructed from polyethylene mixed with a radiation opaque material. An intra-uterine device constructed with polyethylene of an appropriate diameter can be deformed with a small amount of force and yet is elastic enough to return to its original configuration within a short period of time after the force is removed. Polyethylene is also a material which has been well tested for use in intra-uterine devices and found to be inert. As previously specified, the radiation opaque material makes it possible to determine by the methods of radiology the exact location of the device after it has been inserted.

The three looped intra-uterine device of this invention is inserted through the cervix into the uterine cavity by the standard technique which employs a thin-Walled cannula as shown in FIGURE 9. The cannula has a rigid tubular body 42 with a flexible tubular end portion 44 and a push rod 46.

For a typical insertion, the attached tail 4 of the device is threaded through the cannula from the uterine end and the three looped intra-uterine device 52 is pinched together and inserted into the flexilble end portion 44 of the cannula and the push rod is inserted through the other end as shown in FIGURE 9. Unless assembled under aseptic conditions an appropriate aqueous or gaseous sterilization is now made.

The cannula is then inserted through the cervical canal 54 of the woman and into the bottom of the uterus 56 as shown in FIGURE 10. The push rod 46 is pushed manually and gently axially frontwards thereby forcing the intra-uterine device 52, shown partially expelled, from the flexible end portion 44 and into the uterine cavity 21 where the device returns to approximately its original shape as shown in FIGURE 11. The push rod and cannula are withdrawn leaving only the tail extending through the cervix into the vagina.

If it is desirable, the cannula 42 can have one or more flanges attached to it which can be movable or fixed as desired to aid the physician in inserting the cannula to a proper depth and orientation within the uterine cavity.

Although only a hand or laboratory method for manufacturing these intra-uterine devices has been described, it is clear that any other techniques such as injection molding or machine fabrication is suitable. The laboratory method enables the device to be tailored to any desirable set of dimensions and this is an important feature. The laboratory method also allows the fabrication of various shaped devices still having the basic configuration of three loops. For instance, the mandrels 12 can be set vertically wit-h respect to the plane of the template 10, or at various other angles. The latter gives a sequential angular arrangement having a final shape with the loops angled to the plane of the device somewhat like a ships propeller.

A simple annulus of the inert endless material 2 has been shown to be useful as a starting material in the fabrication of these intra-uterine devices, but there can be many other useful modifications of this. For instance, it might be desirable to use a double-looped ring of the inert endless material to start with. The choice of starting material within the limits already described is left to the fabricator who is in a position to best know which initial shape will be easiest to manipulate into the final desired shape.

The inert endless material can be treated in any way which will not destroy its inertness or elastic qualities to aid in detecting whether it is in correct position or not. The addition of barium sulfate to make it radiation opaque has been described but many other techniques can be envisioned. One alternate method would be to use a material electrically conductive in nature whereby its presence could be substantiated quickly by an electric induction measuring instrument placed on the lower abdomen.

The ultra-uterine device of this invention is useful for preventing pregnancies in women.

One advantage which this device has over those of the prior art is its geometrical con-figuration. The three loops are designed to obtain maximum filling of the uterine void while exposing a minimum of the device to the pushing effect of the fundus muscle thereby resulting in a greater resistance to expulsion than any of the prior art devices. The three loop configuration additionally imposes minimum barrier action to the transit of the ovum through the uterine cavity. The free channels offered to the passage of the ovum give it minimum opportunity for contact with the uterine walls thereby resulting in a much lesser likelihood of implantation upon the uterine walls.

Another advantage over the prior art is the smooth, continuous nature of this in-tra-uterine device. The elimination of any free ends or any blunt or cuspate forms makes this device much less likely to pierce the delicate uterine walls either upon insertion, removal or while the device is in place. It is essential that the intra-uterine device of this invention be fabricated from a material which has no free ends initially. The free ends make a device much more likely to pierce the uterine walls and this problem is not eliminated by binding or tying the free ends together because this necessarily results in a 'blunt or cuspate form exactly in contradistinction to the smooth, continuous nature which is desirable and which is achieved by the intra-uterine devices of this invention.

The devices of this invention are also more adaptable to a variety of uterine cavity shapes and dimensions than prior art devices because of their smooth, continuous nature and because of the geometrical configuration of three loops. Each of the three loops is free-moving with respect to the other loops giving the whole device great degree of flexibility. The smooth, continuous nature of the device allows it to find and gently press against the uterine walls without damaging or irritating them.

This device has a further advantage over the prior art in that it can readily and easily be formed in a variety of sizes and shapes within the basic configuration of three continuous loops which makes it readily adaptable to insertion in a wide range of uterine cavities.

What is claimed is:

1. A trefoil intra-uterine device which comprises an inert endless material in the shape of three continuous freely movable adjacently-positioned loops said loops being interconnected such that the two terminating portions of each loop continue smoothly into the terminating portions of the adjacent loops, said intra-uterine device capable of being deformed by the application of a small amount of force and being sufficiently elastic to return substantially to its original shape when the force is removed.

2. The intra-uterine device of claim 1 wherein the inert endless material comprises a polymer selected from the group consisting of polyamides, polyolefins and polyesters.

3. The int-ra-uterine device of claim 1 wherein the three continuous loops lie substantially within one plane.

4. The intra-uterine device of claim 3 wherein the inert endless material comprises a polymer selected from the group consisting of polyamides, polyolefins and polyesters.

5. The intra-uterine device of claim 3 wherein the inert endless material comprises a polymer of a compound selected from the group consisting of ethylene, propylene, tetrafluoroethylene, hexamethylene adip amide, acrylic acid, methaorylic acid, terepht-halic acid, and esters of acrylic, methacrylic and terephthalic acids.

6. The intra-uterine device of claim 3 wherein the inert endless material comprises a polymer of ethylene having a cross-sectional diameter of from about 0.70 millimeter to about 2.20 millimeters. V

7. The intra-uterine device of claim 3 wherein the inert endless material comprises a multifilament of a polymer selected from the group consisting of polyamides, polyolefins and polyesters.

8 8. The intra-uterine device of claim 1 wherein all three of the loops are crossed.

9. The intra-uterine device of claim 1 wherein two of the loops are crossed and one of the loops is uncrossed. 10. The int-ra-uterine device of claim 1 wherein one of the loops is crossed and two of the loops are uncrossed.

References Cited by the Examiner UNITED STATES PATENTS 2,122,579 7/1938 Meckstroth 128-130 2,176,559 10/ 1939 Meckstroth 1'2-8l30 3,077,879 2/1963 Knoch 1'28l30 3,200,815 10/1 965 Margulies 128l30 3,250,271 5/1966 Lippes 1-28-130 3,253,590 5/ 1-966 Biirnberg et al. 128130 ADELE M. EAGER, Primary Examiner.

Claims (1)

1. A TREFOIL INTRA-UTERINE DEVICE WHICH COMPRISES AN INERT ENDLESS MATERIAL IN THE SHAPE OF THREE CONTINUOUS FREELY MOVABLE ADJACENTLY-POSITIONED LOOPS SAID LOOPS BEING INTERCONNECTED SUCH THAT THE TWO TERMINATING PORTIONS OF EACH LOOP CONTINUE SMOOTHLY INTO THE TERMINATING PORTIONS OF THE ADJACENT LOOPS, SAID INTRA-UTERINE DEVICE CAPABLE OF BEING DEFORMED BY THE APPLICATION OF A SMALL AMOUNT OF FORCE AND BEING SUFFICIENTLY ELASTIC TO RETURN SUBSTANTIALLY TO ITS ORIGINAL SHAPE WHEN THE FORCE IS REMOVED.

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