Mechanisms of action as contraceptives by copper IUCDs

The way an IUD works as contraceptive is not fully understood. The most recent studies however indicate that the very presence of an IUD impedes the movement of sperm inside the womb thereby preventing fertilization of eggs. This action applies both to inert i.e. non-medicated IUDs (not available nowadays) and modern medicated IUDs. Additionally, copper released from copper containing IUDs disrupts sperm-oocyte interaction. We know that union between sperm and ova which occur in egg transport tube are depended on about dozen of enzymes. Released copper ions impair the efficacy of such enzymes involved in the fertilization process. Thus copper IUDs acts prior to fertilization and thus it is not an abortificient per se. Copper ions which diffuse from the copper bearing IUDs also damage the spermatozoal enzymes system and other enzymes present in the womb necessary for blastocyst (future embryo) implantation. In contrast to oral pills neither copper bearing IUDs nor the hormone containing IUDs alter ovary and function and suppress release of eggs.

            In summary, the main effect of copper IUDs is prevention of fertilization and even if fertilization occurs there is ‘implantation blocking effect’ which acts as a back-up contraceptive mechanism.

For last several decades modifications of size, shape and chemical content are being aimed at to reduce the expulsion rate of side effects while maintaining the exceptionally high effectiveness and safety profiles of IUDs. Reproductive scientists are working on different frame designs too. In the process frames of different sizes and shapes with various active substances incorporated in the frame for pregnancy prevention has been made available. Some are still in newer clinical trial phase. Hopefully, IUDs will bring many more options for fertility regulation. The uterine cavity has a hollow space. However, in reality, this space, which varies in size and shape peculiar to each woman, can better be described as a potential cavity that widens at the tubal openings. The area adjacent to the tubal openings is often described as being overly sensitive for irritation, and hence, leads to increased uterine contractions when IUDs are fitted. So scientists are trying hard to design such IUDs which will minimize repeated trauma in these parts of uterus i.e. the most sensitive parts.

            As on in 2004, Chinese women had 21 types of IUCs to choose from. Examples of research on in IUC include smaller less bulky devices intended to geometrically adapt to smaller nulliparous uteri, frameless copper IUDs fixed to the endometrium with a thread, devices with movable joints in the cross bars to help them expand and contract with uterine contractions and adapt to different uterine sizes and contours (geometric adaptation). Some newer devices have cervical components and cervical anchoring systems. Still smaller devices appropriate for the smaller atrophic perimenopausal uterus are also under clinical trial. For detailed information on newer devices reader is requested to refer appendix.

Remarks on the string of IUD

The only commitment of the client after the IUD is fitted is to cheek the presence in the upper part of vagina at monthly intervals. Thus it is worthy to know few relevant points pertaining to the string attached to IUD.

Both copper medicated and hormone containing IUDs have one or two ‘filaments’ or ‘strings’ – that is threaded through a hole in the bottom of the vertical arm of the device which is shaped as T. The strings are tied in the device with a knot and strings hang through the lower opening of the cervix into the upper birth canal. The string is monofilament i.e. a single strand of strong plastic. Contrary to popular belief, this thread which hangs in the birth canal does not absorb fluid from birth canal neither transmits bacteria up into the womb. The partner does not feel the thread during lovemaking process neither the male organ is hurt by the thread.

The string has two purposes. It is primarily meant for easy removal of the device with the help of an instrument called ‘artery forceps’. The string also gives an opportunity to the woman clinician to know if the IUD is still in the correct position i.e. inside the womb. As said earlier, the women or her husband should periodically check (once a month is sufficient) its presence by touching the string. It is best palpated in squatting position or else woman can put one foot on a low tool and then insert her index and middle fingers in the birth canal. It should be searched more in backwards than upward direction. Usually, the thread is readily palpable. If not, then one can put her fingers up in the birth canals. When she will be able to feel cervix which feel like tip of nose with a small hole i.e. depression at centre. Some amount of mucus is easily felt at this part and it is in this portion the string should be searched.

If the string seems to shorten or lengthen, the IUD it may mean that have moved up inside then womb or has come down. This mandates an ultrasonography (imaging the womb) to verify correct location of IUD in relation to longitudinal axis of womb (uterus).

If the string can’t be located at all it may mean that IUD has expelled spontaneously possibly without the knowledge of the acceptor. On very rare occasion device may have perforated the womb and travelled to tummy (abdomen). In summary the purpose of putting a sting in IUD is as follows –

a)     It satisfies the client that the IUD has not fallen off the body.

b)     It helps in easy removal of IUD.

c)      If there is there is lengthening or shortening of thread then it implies that IUD has either come down from womb or has coiled up in the womb.