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What is an ectopic pregnancy?
An ectopic pregnancy occurs when an embryo begins to develop at a site other than the wall of the uterus. This occurs in about one in 100 pregnancies.  During a normal pregnancy, an egg and sperm meet and join in one of the fallopian tubes and begin to develop new cells - this is called an embryo. The embryo then travels through the fallopian tube and becomes implanted in the inner lining of the uterus, where it develops and grows into a fetus and, finally, a baby.
In most cases of ectopic pregnancy, the embryo does not travel through the fallopian tube and instead implants itself in the tube or a place other than the uterus. Unfortunately, a fallopian tube cannot stretch to accommodate a growing embryo the way that the uterus does. In some cases, your body will initiate a miscarriage, while in other cases the embryo will continue to grow in the abnormal location and can lead to the fallopian tube rupturing, causing internal bleeding.
An ectopic pregnancy occurs when an embryo implants in a place other than the uterus. Most non-uterine implants occur in a fallopian tube, while other rarer sites include the cervix, an ovary, or the site where the fallopian tubes joins the uterus. An ectopic pregnancy generally occurs when an embryo cannot travel through a fallopian tube because the tube has been blocked, narrowed, damaged or is abnormal. This can be caused by:
- Previous infections including pelvic inflammatory disease;
- Surgery including female sterilisation, and;
- Defects of the fallopian tube from birth.
Risk factors that increase the chance of having an ectopic pregnancy can include:
- Having multiple sexual partners, which can increase the risk of infections;
- Having previous sexually-transmitted infections (such as gonorrhoea and chlamydia);
- Being infertile, which may be due to tubal abnormalities;
- In vitro fertilisation (IVF) can, in rare cases, result in an ectopic pregnancy, and;
- Having previous ectopic pregnancies.
Signs and symptoms
Signs and symptoms that an ectopic pregnancy is occurring do not always appear. Many cases of ectopic pregnancy are not realised until the fallopian tube ruptures. Signs of an ectopic pregnancy can include:
- A missed period;
- Lower abdominal pain;
- Vaginal bleeding, and;
- General signs of pregnancy (tender breasts, frequent urination or nausea).
Signs and symptoms of a fallopian tube rupture include:
- Severe pain;
- Vaginal bleeding;
- Light-headedness or dizziness;
- A drop in blood pressure, and;
- Fainting and shock.
After a fallopian tube rupture it is important to seek treatment as soon as possible, as this is potentially fatal.
Methods for diagnosis
The aim of ectopic pregnancy diagnostic tests are to identify if an embryo is growing in a place other than the uterus. This can involve using an ultrasound, blood test and laparoscopy.
An ultrasound is a test used to produce images of your body's internal structures. A specific type of ultrasound, called a transvaginal ultrasound, involves the insertion of a transducer into the vagina to view the uterus and other pelvic organs. A transvaginal ultrasound is used to check for an embryo that is outside the uterus, for example, in a fallopian tube. This can successfully identify ectopic pregnancies in most cases that are in their fifth or sixth weeks. However, it is important to note that sometimes an ultrasound will not detect an ectopic pregnancy.
A blood test can be used to help diagnose an ectopic pregnancy. A blood test is used to measure levels of human chorionic gonadotropin (hCG), a hormone produced by the placenta that can be used to measure the progress of a pregnancy. If there is an abnormally high level of hCG, but no evidence of an embryo in the uterus by ultrasound, an ectopic pregnancy is suspected. Careful monitoring by a doctor will be required to determine whether there is an ectopic pregnancy.
A laparoscopy is used as a final diagnostic measure. A laparoscopy involves a small incision into the abdomen and the insertion of a thin tube with a camera attached to view the internal organs. This can identify if an embryo is developing in a fallopian tube.
Types of treatment
As an ectopic pregnancy will unfortunately not be able to reach full-term, it is important to stop the growth as soon as it is recognised. This reduces the risks of complications including damage to or rupturing of the fallopian tube and internal bleeding. Treatment can involve either medication or surgery.
It is possible for a medication called methotrexate to be used in ectopic pregnancies to stop the growth of the embryo. It is given as an intramuscular injection and the levels of hCG are monitored to ensure they decrease. If the level of hCG remains high, another injection of methotrexate may be required. It is important to remember that this is performed to prevent unwanted damage to the fallopian tube and serious complications, including internal bleeding, during the pregnancy.
To treat an ectopic pregnancy, surgery is sometimes required. This is performed if a fallopian tube has already ruptured or likely to rupture, methotrexate cannot be safely used or methotrexate was not effective. To perform this treatment, laparoscopic or 'keyhole' surgery is generally used. This involves a small incision into the abdomen and the insertion of a thin tube with a camera attached to locate the ectopic pregnancy site. Small instruments are inserted at nearby sites and the embryo is removed. The ruptured fallopian tube will also be repaired if possible, but in some cases, it is removed to stop excessive bleeding.
If unnoticed or left untreated, complications associated with ectopic pregnancies include rupturing of the fallopian tube leading to massive internal bleeding. This must be treated as an emergency to stop the bleeding, because in rare cases, excessive bleeding can result in death.
Rupturing of a fallopian tube can also cause irreparable damage to the tube, preventing eggs from passing through it. Thankfully, women have two fallopian tubes that eggs can travel through, so although one may be damaged, the other may be unaffected and becoming pregnant again is still possible.
An ectopic pregnancy is an unwanted complication that occurs in about one in 100 pregnancies. Unfortunately it results in the loss of the embryo and miscarriage. Thankfully, an ectopic pregnancy can sometimes be detected early by an ultrasound and blood test. This allows for treatment to be performed to remove the embryo from the fallopian tube. It is important to do this as fallopian tubes cannot stretch to hold a growing baby. It will give you the best chance of preventing damage to the fallopian tubes.
In some cases, an ectopic pregnancy will not be realised until the fallopian tube ruptures. This will require immediate treatment to stop internal bleeding and repair the fallopian tube if possible. After an ectopic pregnancy, the chance of a normal pregnancy is 60-65% and having another ectopic pregnancy is approximately 10-15%. 
You cannot prevent an ectopic pregnancy from occurring, but it is possible to decrease the risks of ectopic pregnancies. To do this, it is important to reduce the chances of any infections that can damage the fallopian tubes. This particularly includes pelvic inflammatory disease, which can occur as a complication of sexually-transmitted infections. To prevent infections, it is best to limit your sexual partners and use barrier contraception such as condoms with new sexual partners. It is also a good idea for you and any new partner to be checked for any sexually-transmitted infections.