The invention relates to a device ich is to be placed in the uterus or uterine cavity and to which or in which certain substances such as metal ions, hormones or therapeutic substances which are to be effective in the uterus for a certain time can be attached, and which device comprises a stem wi ^' t resilient or flexible arms projecting on either side of the stem near or at one ex¬ tremity thereof, and the extremity of each of the two arms is bent through an angle great ^' er than 90° so that the extremities point towards the stem and the arms are thus built up of three parts, i.e. a first part and a second part or extension, and a bent piece between them. Devices which can be placed in the uterus for precluding pregnancy and which are known in medical circles by the name "iπtrauteriπe device" or "IUD" are generally known. A device of this type which essentially consists of a "T"-shaped body is described in U.S. Patent 3,533,406. This T-shaped body is to be placed entirely in the uterus. The transverse bar then presses against the fundus or right upper section of the uterus, and the lowermost extremity of the steβi is directed towards the orifice of the cervix. It has been found that this de¬ vice is unsatisfactory in a relatively large number of cases. In a number of cases the device is rejected and in a large number of cases excessive bleeding occurs and such a device is experienced as being painful. Further¬ more, in a relatively large number of cases pregnancy is not prevented. The fact that this device is inappro- priate is attributed to the extremities of the transverse bars becoming immobilized in the uterine wall, or being at least pushed in, which results in damage to the endo- metrium or the mucous meibrane layer.

U.S. Patent 4,045,131 describes a device likewise having a T-shaped appearance. The extremities of the transverse bar are provided with extensions bent through an angle and directed to the stem. The upper transverse bar is, however, bent towards the outside and downwards and the dimensions and shape of the device are such that

the device becomes secured as optimally as poss-ble in the uterine cavity. The transverse bar is ben: down¬ wards,, and the extremities near the bent p ece thus point downwards at an angle, to prevent the device frα sliding downwards to the uterine neck or cervix. If, fcr example, the uterus contracts, the fundus will press on the top of the device and the extremities of the transverse bar will therefore be pushed into the wall of the uterire cavity. To prevent the extremities from penetrating the wall ex- tensions are made at the extremi ies with the result that the area of pressure is increased. This known device also has the drawback that pain may occur in a -elatively large number of cases, the device is rejected and bleed¬ ing occurs. Measurements with measuring instruments devel¬ oped specifically for this purpose have shown that the uterine cavity in vivo is smaller than assumed hitherto. All of the devices, known to date, which are to be placed in the uterus are shaped such that the best possible anchorage in the uterine cavity is obtained. For this purpose, the dimensions of these known devices are all too large. This is also very probably the reason why pain is felt regularly and why there is often bleeding. This is partially caused by damage to the wall and trte tissue at the inner side of the uterine cavity. Another reason may be that the stem extremity of the device projects into the cervix, especially during the period when e uterus contrac s greatly .

The invention has as its object a device which can be placed in the uterine cavity and w ich has or can have dimensions such that the inner wall of the uterine cavity is hardly irritated, if at all.

This ob ect is achieved with a device according to the invention in that the three parts of each arm to- gether form an arrow the legs of which consist of the first part and the second part or extension, these parts being compliantly connected to each other by the bent piece, and the direction of the first part near the bent piece being horizontal or upward. It has been found that

these measures make it possible to construct a de ce which approximately corresponds to the dimensions of t •" e uterine cavity in vivo, or is even smaller, without t h _ device being rejected. The prejudice that a device must be anchored as optimally as possible in the uterine wa I . was found to be incorrect. Another great advantage of :he device according to the invention is that there is harc ^' .y any bleeding outside the first period beyond the normal. occurring bleeding. The angle enclosed by the first part of the arm and the second part or extension is preferably smaller than 60° so that these extremities can easily slide into the narrowing leading to the fallopian tubes, which is of particular importance when the uterus con¬ tracts greatly. The arrow shape formed by the first part, the second part or extension and the bent part of each arm is preferably a shape between a V and a U. This is par¬ ticularly important when inserting the device and also when the device is placed in- the uterine cavity. With the correct shape the bent extremities of the arms will not easily hook into the wall of the uterine cavity or get stuck. By choosing the position of the extensions of the arms such that they extend approximately parallel to the sidewalls of the uterine cavity it is achieved that the extremities of the arms slide easily along these walls which is particularly important when the uterus contracts. Due to the fact that the device is manufac¬ tured of flexible material the two legs of the arrow can moreover easily move towards each other so that the ex- tensions can slide even-better along the sidewalls of the uterine cavity without damaging the latter.

In a preferred embodiment of the device accord - ^' ng to the invention the point at which the arms are fastened to the stem is reinforced so that the arms resume the original position more easily once the device has been inserted in the uterine cavity. This is because it is important that the arms resume the correct position after insertion.

The thickness of the small arms and the exteπ-

s ioπs of the small arms is preferably less than 1.5 mm and, when manufactured of plastic mater al, preferably 1.1 mm or more. 'It is important that the small arm is so thin in order that the extensions can be sufficiently compliant relative to the first part of the small arms. The small arms should be less thin at the other side because there may otherwise be plastic deformation, and the device will no longer be capable of returning to the original state. In particular, it is very important that the small arms are directed sideways when the device is inserted in the uterine cavity. Another reason why it is important to make the small arms as thin as possible is the fact that bacteria may become settled on the sur¬ face of the plastic. Thin round arms have a small sur- face area. The thickness of the stem of the device is preferably smaller than 2 mm and is preferably of the order of 1.5 mm. In addition, two contrad ctory inter¬ ests are to be served, namely the thinner the stem the less is the risk of bacteria; the thicker the stem the more metal, hormones or therapeutic substances can be attached to the stem*.

Measurements on the uterine cavity in vivo have shown that the width of each device ought to be adapted to the i ensions of a uterine cavity. It has generally been found, however, that it is sufficient, at least for European women, to have a limited number of different dimensions of the device. In principle, three standard dimensions for the maximum width of the devices are suf¬ ficient, i.e. 20 mm, 24 ^' m and 28 mm. This width is coupled with a maximum length of the stem of 28 mm, 30 ram and 32 mm, respectively. This _# length of the stem is more or less the ma imum acceptable length because the lower end of the stem must not reach the region of the internal os which is rich in nerves. For this purpose account is to be taken of the contraction of the uterus and the flexion w ch most uteri have at the transition of the uterine cavity into the cervix.

It has been found in practice that, when a limited number of standard dimensions of the device

according to the invention is taken as a starting point and the uterine cavity was measured beforehand, the accompanying symptoms such as excessive bleeding, pain and rejection ^' of the device can be prevented virtually entirely when the correct dimension of the device is used for a certain measured width of a uterine cavity.

The invention will be illustrated in detail by reference to the drawing, in which:

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Figures 1, 2, 3 and 4 show four different pos- sible embodiments of the device according to the inven¬ tion;

Figures 5 and 6 show a device as represented in Figure 1, provided with copper wire;

Figure 7 shows the device according to Figure 1 in which the small arms are folded downwards;

Figures 8, 9 and 10 show the uterine cavity in cross-section with the device according to the invention during insertion into the uterine cavity;

Figure 11 shows the uterus in cross-section in two positions with a device according to the invention;

Figure 12 stjows a view of the uterus near the cervix;

Figure 13 shows a cross-section through a uterus perpendicular to the section as represented in Figures 8, 9 and 10;

Figure 14 shows a view of a small bar for inser¬ tion of a device according to the invention.

Figures 1, 2, 3 and 4 show four different pos¬ sible embodiments of a device according to the invent on. Each device consists of a stem 1 with two arms 2, 3 pro¬ jecting at either side at the upper extremity. The de¬ vice according to Figure 1 shows two arms 2, 3 consist¬ ing of a first part 4 which is straight and is then bent through an angle of the order of magnitude of 35°, and thereafter a second part or extension 5 which points in the direction of the stem 1 and has a length of approxi¬ mately 6 mm. The hook over which the extremities of the ar«s 2,3 are bent is circular and in this case has an inner diameter of 2 »a and an outer diameter of approxi-

mately 4 mm. The thickness of the snail arms and the bent extensions is approximately 1. ^* mm. The thickness of the stem is appro imately 1.5 mm round. The snail arms as well as the stem are circular. A small hole 6 through which a small wire 7 is fitted is attached near the lower end of the stem 1. The device is provided with a thickening 8 present at the upper side of the device at the point where the stem 1 is fastened to the arms 2,3. The angle which the straight part 5 of one of the arms 2,3 forms with t"he stem 1 is in this case 90°.

Figure 2 shows a device which also consists of a stem 1 w th a small hole 6 through which a small wire 7 extends near the lower side. The first part 9 of the arms 2,3 is in this case not straight but slightly bent upwards. Figure 3 shows a device according to the inven¬ tion in which the angle through which the extremities of the two arms 2, 3 are bent is sharp and has approximately a V shape. Figure 4 shows a device according to the invention in which the angle between the first straight part 5 of the arms 2, 3 and the ste« is greater than 90° and the arms thus extend obliquely upwards relative to the stem 1.

Figure 5 shows a device according to the inven¬ tion such as is represented in Figure 1 in which a wire 10 is wound round the stem. In this case, this is a copper wire used as a means for introducing copper ions into the uterus during a lengthy period. Figure 6 fur- theraore shows the possibility of fitting wires not only to the stem but also to. the ^" bent parts or extensions 5 of the device; as a result copper ions will be present even at the sidewall of the uterine cavity. In the saae manner other therapeutic or hormonal agents can be at¬ tached at the outer surface of the stem 1 andOr arm parts 4, 5. For this purpose it should be possible to attach wires at the outer surface of the device which are impregnated with the desired agent. Figure 7 shows the downwardly folded state of the device according to the invention; this is the position of the arms when these are pushed into the uterine cervix by means of a snail

t u b e 1 1 .

Figures 8, 9 and 10 show a cross-sect ion of a uterus 12 with the fallopian tubes 13, the uterine cavity

14 and' the cervix 15. Figure 8 shows the device according to the invention at the instant at which this is pushed into the cervix 15 by means of the small tube 11. The arms 2, 3 will be bent downwards away after which the small tube is pushed with the device through the cervix

15 to arrive, subsequently, in the uterine cavity. When a device having the correct dimensions is used the arms

2, 3 will subsequently have sufficient space near the upper side of the uterine cavi y for springing back into the original state sideways and upwards. When the small tube is then taken out of the, uterine cavity again the device will remain in the uterine cavity because the arras 2, 3 which are extended sideways will press against the sidewalls of the uterine cavity and as a result of this will remain clamped between the sidewalls 17, 18 of the uterine ca ity. Figure 11 shows the uterus 12 in the state in which it is contracted; the state of the uterus at the instant at which it is relaxed is at the same time shown in dashed lines. In the state in which the uterus is contracted the arms 2, 3 of the device will be somewhat bent and, such as represented here, sl ightly bent upwards and the bent parts 5 of the arms 2, 3 will possibly be pushed sl ightly inwards, i.e. the extension 5 towards the first parts 4 of the arms. In the relaxed state of _, the uterus this device, as represented in Figure 11, will resume the position as shown in Figure 10. The device can be easily removed at a certain desired instant by means of the small wire 7.

Figure 12 shows a view of a uterus and in par¬ ticular that section which contains the cervix. A small section of the device and also the extensions 5 of the arms 2, 3 together with the small tube 11 for introducing the device into the uterine ca ty are still inserted in the cervical os which is somewhat sl it-shaped.

Figure 13 shows a cross-section through the uterus

- a - such as represented in Figures 8, 9 and 10 in a crecfon perpendicular to the section represented in those figu-es. As is often the case, the uterus shows flexion a r z the device must not be so long that the lowermost end reac ^h es the section of the inner uter ne cavity which is -ich ^* n nerves. Figure 14 shows a further small tube witt which the device can be inserted in the uterine cavity and to which certain indicators can be attached such as, for example, a tape measure with a number of coloured rings 16.

The device according to the invention has grear advantages over the devices known to date, in that the device according to the invention is adapted to the shape of the uterine cavity and thereby takes account of the size of the uterine cavity in vivo because the latter may be smaller, as a result of contraction, than measured after it-has been removed from the body. The device ac¬ cording to the invention will easily remain within the cavity, even when the uterus contracts, without the de- vice being pressed against the walls of the cavity in a manner such that parts of the de ice are pushed into the wall. Even the layer of mucous membrane in the uterine cavity is hardly damaged by the device according to the invention. As a result of the fact that the de ce is small in size, and therefore lightweight, the weight will hardly exert forces on the device which could be a cause for the device to be rejected or at least to fall out of the cavity. A further advantage of the small size is that the outer surface _. area of the device is very small with the result that fewer bacteria may be present on the device. Specifically, it is generally known that some bacteria such as S taphylococcus ep didermi di s can multiply on the surface of plastics. Only in the first month after insertion of the device into the uterus may there be soae- what «ore bleeding than normal, because the Layer of raucous membrane and the muscular tissue of the uterine cavity aay be sl ghtly irritated by the insertion.

Since it is possible at present to deteraine and measure very accurately the inner dimensions of the uterine

cavty in a living individual the s ze of the uterine c av ^■ ty can be taken into account and the appropriate size of the device determined beforehand. It has been found that at least in Europe three standard dimens ions are sufficient, that is to say a length of t e stem of 28 urn, 30 mm and 32 mm with an appropriate maximum width of the device of 20 mm, 24 mm and 23 mm, respectively. Two further dimensions may optionally be added to this, that is to say: stem length 26 mm and 34 mm with the appropriate dimensions for the maxiaum width of 16 mm and 32 mm , respectively.