The
levonorgestrel-containing intrauterine device (LNG-IUS) is a plastic
T-shaped frame from which a small amount of the hormone
levonorgestrel is released daily into the woman’s blood.
(Levonorgestrel is a progestin-type substance widely used in the
manufacture of implants and oral contraceptives).
The
main mechanism of action is to delay the development of the uterine
mucosa (endometrium).
Who
can use it?
It
can also be used in women with heavy menses or who are in
premenopausal stage (who are over 40 years of age).
What
is it?
The
T-LNG is a small plastic device in the shape of the letter T and
contains the hormone called levonorgestrel. It is placed inside the
uterus and lasts for 5 years. It comes in two sizes (Mirena that
contains 52 mg of LNG and lasts 5 years and Jaydess that contains
13.5 mg of LNG and lasts 3 years).
How
do they avoid pregnancy?
Although
most cycles are anovulatory, the main mechanism of action is
thickening of the cervical mucus, which averts the passage of sperm
from the vagina to the uterus.
How
are they used?
The
LNG IUD is inserted during the first 7 days of the menstrual
cycle. You can also be placed without menstruation if you are sure
there is no pregnancy and, in this case, you need contraceptive
protection or sexual abstinence for 7 days. It can be placed
immediately after an abortion and after 4 weeks of a birth. It must
be placed by trained health personnel.
What
is the effectiveness of the T-LNG?
It
is very effective. The failure rate is 0.2%, that is, approximately
two out of every 1,000 women who use this method for one year can
become pregnant.
Medical
eligibility criteria for T-LNG
The
T-LNG shares the medical eligibility criteria for progestogen-only
pills and implants and intrauterine devices. In general, women who
have cancer of the uterus or breast or a sexually transmitted
infection due to gonorrhea or chlamydia, among other diseases, should
not use it. Its use is not recommended to those who are at risk of
acquiring one of these infections.
What
are the most frequent side effects? It can cause some discomfort such
as mild pain while putting on or pulling out, pain in the lower
abdomen and general discomforts like other hormonal contraceptives.
The
effect on the endometrium has beneficial effects and the
levonorgestrel IUD can be used as a
treatment for women who experience excessive uterine bleeding
(idiopathic metrorrhagia, uterine myomatosis, adenomyosis, blood
dyscrasias, endometrial hyperplasia); as hormone replacement therapy;
for endometrial protection in users of tamoxifen and as a treatment
for pelvic pain and endometriosis.
