Friday, 19 April 2013

Ectopic pregnancy

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.

Culled from Punch  Online

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