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.
