Ectopic pregnancy is when the fertilised egg is implanted outside the uterine cavity. The word ectopic
is from a Greek word ‘ektopos,’ meaning ‘out of place.’ The real place
for normal pregnancy is the uterine cavity (that is the cavity of the
womb), as the place designed to expand and accommodate foetal growth and
development.
The commonest site for ectopic pregnancy
is the fallopian tube. About 98 per cent of ectopic pregnancies occur
in the tube. Other areas for ectopic pregnancy include the cervix,
ovaries, cornual region (angle) of the uterus, abdominal cavity, etc.
Normal eggs are fertilised in the
fallopian tube by the sperm from the man, then the fertilised egg now
moves to the uterus for implantation, but whatever factor that hinders
or slows down the movement of the fertilised egg from the tube where it
is fertilised, to the womb where it is supposed to implant, may lead to
ectopic pregnancy.
In the tubes, there are finger-like
structures that help the movement of the fertilised egg from the tube to
the womb normally. Factors that predispose to ectopic pregnancy will
include damage to fallopian tube, either from pelvic infection such as
pelvic inflammatory disease (an infection and inflammatory disorder of
the upper female genital tract, including the uterus, fallopian tube,
and adjacent pelvic structures).
Common organisms are Chlamydia
trachomatis, Neissseria gonorrhoea, Gardenerella vaginalis, haemophilus
influenza, etc). Where the inside of the tube has been damaged and the
system that assists the movement of the fertilised egg is also damaged,
the pregnancy may get stuck in the tube and get implanted wrongly,
leading to tubal pregnancy, which is the commonest form of ectopic
pregnancy.
The commonest cause of pelvic inflammatory disease includes Chlamydia trachomatis.
Unfortunately, most
women with this infection may not present with any symptom. In fact,
most women with Chlamydia infection are not even aware that they are
infected. Another organism that can caused PID is Neissseria gonorrhoea,
which also increases the risk of ectopic pregnancy.
The more the episodes of PID, the higher
the incidence of ectopic gestation. For example, after three episodes
of PID, the risk of ectopic pregnancy could be as high as 75 per cent.
Worse still, previous history of ectopic
pregnancy is a predisposing factor for another ectopic pregnancy. In
the case of history of previous tubal surgery, there is an increased
tendency for ectopic pregnancy from the tube.
Cigarette smoking has been associated
with increased risk for ectopic pregnancy, though specific mechanisms
connecting smoking with ectopic pregnancy are not straight-forward; but
studies in both human and laboratory animal showed that smoking may
delay ovulation, and reduce tubal and uterine motility. All these
mechanisms combine to predispose smokers to increased risk of ectopic
pregnancy.
Again, generally, any form of
contraception will lower the risk of pregnancy, including ectopic
pregnancy. However, if contraception fails and the woman on
contraception eventually gets pregnant, there is an increased risk of
ectopic pregnancy, compared to women who are not on contraception. Those
who are highly at risk are those who take two-monthly or three-monthly
injection (i.e. progesterone only injectables, progesterone only
implant, or intrauterine contraceptive device).
For clear understanding, Copper-T (a
form of intra uterine contraceptive device that is very popular in our
environment) does not increase the risk of ectopic pregnancy on its own,
but if a woman on Copper-T gets pregnancy with it, then there is higher
tendency for ectopic pregnancy, compared to women that are not on
Copper-T. The incidence of ectopic with intrauterine device is about 3-4
per cent.
There is also an increase in the
incidence of ectopic pregnancy for women under ovulation induction,
compared to women that are not under ovulation induction.
Some assisted reproductive technologies
are also associated with increased risk of ectopic pregnancy; these
include invitro fertilisation (IVF), transfer of fertilised eggs into
the fallopian tube (Gamete Intra Fallopian Transfer, GIFT).
There is also an increased risk of
heterotrophic pregnancy — that is a situation where there is normal
intra uterine pregnancy, combined with ectopic pregnancy.
Age is also a significant factor in the
incidence of ectopic pregnancy; higher incidences occur between 35-45
years of age when compared to women in the younger age group like 15-25
years.
In older age group, there is less or
reduced uterine or tubal movement (motility). Abnormality of the tube,
e.g. abnormally long tube or abnormality of the uterus (e.g. double
uterus, T-shaped uterus, uterine fibulas, etc) could all contribute to
increased incidence of ectopic pregnancy.
Ectopic pregnancy classically presents
with abdominal pain, absence of menses (amenorrhea), and vaginal
bleeding. These three cardinal clinical pictures may not always be
present, though.
So, presentation of ectopic pregnancy
depends on the site of implantation, age of the pregnancy, either it is
intact or ruptured. Women with multiple sexual partners also have
increased risk of ectopic pregnancy.
To be continued.
