An ectopic pregnancy is when a fertilised egg implants itself outside of the womb, usually in one of the fallopian tubes.
This means the egg will not develop into a baby, which can be devastating to the pregnant woman.
Occasionally, an ectopic pregnancy doesn't cause any noticeable symptoms and is only detected during routine pregnancy testing. However, most women do have symptoms, and these usually become apparent between week 5 and week 14 of pregnancy.
Read more about the symptoms of an ectopic pregnancy.
How is an ectopic pregnancy treated
If an ectopic pregnancy is detected at an early stage, a medication called methotrexate is sometimes needed to stop the egg developing. The pregnancy tissue is then absorbed into the woman's body.
However, methotrexate is not always needed - in around half of cases, the egg dies before it can grow.
Ectopic pregnancies detected at a more advanced stage will require surgery to remove the egg.
If an ectopic pregnancy is left to develop, there is a risk that the fertilised egg could continue to grow and cause the fallopian tube to split open (rupture), which can cause life-threatening internal bleeding.
Signs of a ruptured fallopian tube are:
A ruptured fallopian tube is a medical emergency. If you think that you or someone in your care has experienced this complication, call 999 and ask for an ambulance.
Read more about treating ectopic pregnancy.
Why does an ectopic pregnancy happen
In a normal pregnancy an egg is fertilised by sperm in one of the fallopian tubes, which connect the ovaries to the womb. The fertilised egg then moves into the womb and implants itself into the womb lining (endometrium), where it grows and develops.
An ectopic pregnancy occurs when a fertilised egg implants itself outside the womb. It most commonly occurs in a fallopian tube (this is known as a tubal pregnancy), usually as the result of damage to the fallopian tube or the tube not working properly.
Less commonly (in around 2 in 100 cases), an ectopic pregnancy can occur in an ovary, in the abdominal space or in the cervix (neck of the womb).
Things that increase your risk of ectopic pregnancy include:
In around half of all cases, there are no obvious risk factors.
Read more about the causes of, and risk factors for, an ectopic pregnancy.
Losing a pregnancy can be devastating and many women feel the same sense of grief as if they had lost a family member or partner.
It is not uncommon for feelings of grief and bereavement to last for 6-12 months, although these feelings usually improve with time.
Trying for another pregnancy
How long it is advisable to wait before you try for another pregnancy will depend on your specific circumstances. Your doctor should be able to advise you when (or if) it will be safe to do so.
In most cases it is recommended that you wait for at least two full menstrual cycles before trying for another pregnancy, as this will allow time for your fallopian tubes to recover. However, if you were treated with methotrexate, it is usually recommended that you wait at least three months.
However, many women are not emotionally ready to try for another pregnancy so soon.
Your chances of having a successful pregnancy will depend on the underlying health of your fallopian tubes. In general, 65% of women achieve a successful pregnancy 18 months after having an ectopic pregnancy.
If you cannot conceive in the normal way, then fertility treatment such as in-vitro fertilisation (IVF) may be an option.
IVF treatment is where an egg is fertilised by a sperm outside the womb (usually in a test tube) and, after fertilisation, the embryo is surgically implanted into the womb.
Who is affected
It is estimated that around 1 in 90 pregnancies in the UK develops into an ectopic pregnancy. This is around 10,700 pregnancies a year.
Nowadays, deaths from ectopic pregnancies are extremely rare.
Symptoms of ectopic pregnancy
Some women who have an ectopic pregnancy do not have any symptoms. They may not find out it is ectopic until an early scan shows the problem or a woman's fallopian tube has ruptured.
If there are symptoms, they usually appear between weeks 5 and 14 of the pregnancy. These are outlined below.
One-sided abdominal pain
You may experience pain, typically on one side of your abdomen (tummy), which can be persistent and severe.
Vaginal bleeding is a different type of bleeding from your regular period. It often starts and stops, and can be bright or dark red in colour. Some women mistake this bleeding for a regular period and do not realise they are pregnant.
Less common symptoms
Shoulder tip pain
Shoulder tip pain is felt where your shoulder ends and your arm begins. It's not known exactly why shoulder tip pain occurs, but it usually happens when you're lying down and is a sign that the ectopic pregnancy is causing internal bleeding.
The bleeding is thought to irritate the phrenic nerve, which is found in your diaphragm (the muscle used during breathing that separates your chest cavity from your abdomen). Irritation of the phrenic nerve causes referred pain (pain that is felt elsewhere) in the shoulder blade.
You may experience pain when passing urine or stools.
Diarrhoea and vomiting
An ectopic pregnancy can cause similar symptoms to a gastrointestinal disease and is often associated with diarrhoea and vomiting.
When to seek medical advice
You should always contact your GP if:
When to seek emergency medical treatment
The most serious symptom of an ectopic pregnancy is known as "collapse". This occurs when an ectopic pregnancy has split open the fallopian tubes (tubal rupture) and is causing dangerous internal bleeding.
People who have experienced collapse describe feeling lightheaded (dizzy) and faint. You may also:
If your fallopian tubes rupture, you will need emergency surgery to prevent blood loss. Dial 999 immediately and ask for an ambulance.
In rare cases, a ruptured fallopian tube can be fatal. However, this is very uncommon and in most cases, the fallopian tube can be successfully repaired or removed.
Causes of ectopic pregnancy
In the early stages of pregnancy, an egg is released from one of your ovaries into one of your fallopian tubes, where it is fertilised by sperm.
Each fallopian tube is about 10cm (4 inches) long and lined with millions of moving, hair-like structures called cilia. In a normal pregnancy, the cilia push the fertilised egg along the tube and into the womb, where the egg implants itself into the womb's lining (endometrium) and develops into a baby.
However, if the fallopian tube has been damaged (for example, if there is a blockage or narrowing of the tube), the cilia may not be able to move the egg to the womb, and the pregnancy may develop in the fallopian tube.
Common risk factors
Some of the most common risk factors for an ectopic pregnancy are discussed below.
Pelvic inflammatory disease
Pelvic inflammatory disease (PID) is a bacterial infection of the female reproductive system. Most cases of PID are caused by an infection in the vagina or the neck of the womb (cervix) that has spread to the reproductive organs higher up.
Many different types of bacteria can cause PID, but most cases are due to a chlamydia infection - this is a type of sexually transmitted infection that can be spread during unprotected sex.
Chlamydia often exhibits no noticeable symptoms, so women may not know they are infected. However, the bacteria can cause inflammation of the fallopian tubes, which is known as salpingitis. Salpingitis leads to a four-fold increase in the risk of having an ectopic pregnancy.
Having a previous history of ectopic pregnancy means you have an increased risk of having one in the future.
Depending on the underlying factors, the risk of having another ectopic pregnancy is somewhere between 1 in 10 and 1 in 4.
If you have ever had surgery that involved your fallopian tubes, you have an increased risk of having an ectopic pregnancy. Types of surgery known to increase your risk include:
Taking medication to stimulate ovulation (the release of an egg) can increase the risk of ectopic pregnancy by around four-fold.
The type of fertility treatment known as in-vitro fertilisation (IVF) is not always successful and can accidentally result in an ectopic pregnancy.
This occurs in around 1 in 22 cases of IVF.
The intrauterine device (IUD) and the intrauterine system (IUS) are very effective in preventing pregnancy - the success rate is estimated to be around 99 out of 100 cases. But if a pregnancy does occur when using these types of contraception, it is more likely to be an ectopic pregnancy than a normal pregnancy.
There is also a risk that if you take emergency contraception and it fails to work, any subsequent pregnancy could be an ectopic pregnancy.
Other risk factors
Other potential risk factors for an ectopic pregnancy include: