Diagnosing an ectopic pregnancy

Ectopic pregnancy can be notoriously difficult to diagnose because it often presents with symptoms that can be suggestive of other, more usual, conditions such as gastroenteritis, miscarriage or even appendicitis. Doctors rely on women to give them clear histories about their symptoms and so the more you can tell a doctor about what has changed, what feels different and what is worrying you, the more likely they are to be able to diagnose you. Please do be vigilant and take symptoms that concern you seriously until absolutely proven otherwise. If your instincts are screaming at you that something doesn’t feel right, it’s OK to trust them and ask medical professionals for a reassessment at any time.

The EPT considers that all women of childbearing age presenting with abdominal pain and/ or bleeding should be considered pregnant until proven otherwise.

In diagnosing an ectopic pregnancy, medical professionals are likely to undertake some or all of the following tests. Please click on any that interest you and more information will open up.

Urinary Pregnancy Tests

Urinary Pregnancy Tests

The first and most useful basic test for diagnosing an ectopic pregnancy is a urinary pregnancy test. Because these tests are reliant on the hormone Human Chorionic Gonadotropin (hCG), a hormone produced by a fertilised egg after conception, these can sometimes produce a false negative result because the hormone is not present in high enough levels to test positively.

Ultrasound scanning

Ultrasound Scanning

Whether a woman has a positive urinary pregnancy test or not, if she has ectopic pregnancy symptoms, good practice would then be to investigate with an ultrasound scan, ideally within 24 hours. The sonographer will scan across the abdomen (tummy) first but it is very likely that a transvaginal (internal) ultrasound scan will be required where a specialised probe is placed into the vagina to get a more detailed look at the reproductive organs.

If during the scan a pregnancy – that is a gestation (pregnancy) sac, a foetal pole and a beating heart – can be seen in the uterus, the chance of a coexisting ectopic pregnancy, whilst possible, is unlikely. In a case like this, bleeding may be implantation bleed, bleeding during a healthy pregnancy, or due to an impending miscarriage. Pain may be caused by a normal, healthy corpus luteum cyst, which forms on the ovary after ovulation, swelling to cause pain. Changes to the bowel and bladder may be attributed to hormonal changes, causing the woman to want to pass urine (wee) more often and possibly even be a little constipated (find it hard to open the bowels to have a poo).

If signs of pregnancy can be seen in the uterus, usually a yolk sac but either no embryo or if the embryo is too small to expect to see a heartbeat, this situation is given the medical label of an ‘Intrauterine Pregnancy of Uncertain Viability’ or PUV or IPUV. In this circumstance, you should be offered a repeat scan a week to ten days later to check whether the baby has developed a heartbeat.

This is an emotionally difficult time as it is not clear whether the dates for conceiving were wrong or whether the lady is likely to miscarry. Blood tests will also typically be taken to establish the level of hCG in the blood stream and again 48 hours later, to see how the levels are behaving.

If no pregnancy can be seen in the uterus, or there is a small gestation sac in the uterus without a yolk sac or embryo, the pregnancy will be medically labelled as a Pregnancy of Unknown Location or PUL.  It is important to understand that PUL is not a diagnosis; it is a label given until the final location of the pregnancy can be identified with certainty. In the event of a PUL, blood will be taken to measure serum progesterone and hCG and the hCG test repeated 48 hours later. The doctors would also want to repeat the scan.

Until the location of the pregnancy is known definitively or the serum hormone levels have decreased to below pregnancy levels, there is a risk of complications associated with an as yet undiagnosed ectopic pregnancy. For every 100 pregnancies labelled as a PUL about 10 will subsequently be found to be ectopic; and not all of these will need treatment.

If no pregnancy can be seen in the uterus but there is evidence of free fluid in your abdomen and or a possible ‘mass’ in the approximate location of one of your fallopian tubes, the doctor would then be likely to diagnose a possible ectopic pregnancy. An initial scan will detect over 70% of ectopic pregnancies.

Beta hCG Blood Tests

Beta hCG Blood Tests

The hormone Human Chorionic Gonadotropin (better known as hCG) is produced during pregnancy by specialised trophoblast cells, which are only found in the body as a result of a fertilised egg implanting. Increased progesterone production from the ovary that ovulated prepares the endometrium, but it is the hCG that sustains the pregnancy.

Levels of hCG can first be detected by a normal blood test approximately 11 days after conception and, in a healthy pregnancy, will typically double every 48 to 72 hours, peaking somewhere between 8 and 11 weeks of pregnancy (the end of the second beginning of the third month) and then either plateau or decline and level off for the remainder of the pregnancy It is this early hCG increase that can sometimes give women feelings of ‘morning sickness’.

Your hCG would only need to be tested if you have reached 6 weeks pregnant and the scan does not clearly show a developing pregnancy in the uterus. If doctors think you are a low risk of ectopic pregnancy they may arrange a blood or urine test at an interval or, if they think you are high risk, they will often repeat the scan or blood test in 48 hours and can sometimes take further measurements before they draw final conclusions.

  • A declining hCG result is an indicator that the pregnancy has ended and will be miscarried over the next days or weeks. It can also possibly indicate an ectopic pregnancy that is ‘self-resolving’.
  • A hCG level that is rising by less than 66% over 48 hours means it is likely, but not a certainty, that the pregnancy is ectopic.
  • If levels are found to be rising normally, they can give a suggestion, but not a certain answer, that the pregnancy is implanted in the uterus and that the conception date (the date the egg was fertilised) is wrong.

The following chart is an example borrowed from BabyMed that shows hSG values for a singleton (one baby versus twins) pregnancy. The red line shows the average hCG value for a number of days after ovulation (scale across the bottom of the graph). The yellow line shows the bottom of the low range of hCG values and the blue line shows the high levels of hCG. The green line shows the results of two hSG tests plotted on the graph and joins them together to show the increase line of where they sit compared to the average.

HCG chart
National guidelines

National guidelines

Doctors are at liberty to follow their own hospital protocols in the UK but there are guidelines available to help steer medical professionals. For example:

Nice Guidelines

The National Institute for Health and Care Excellence (NICE) was originally established in 1999 to reduce variation in the availability and quality of NHS treatments and care. In 2005 they merged with the Health Development Agency and began developing public health guidelines. It is a Non Departmental Public Body sponsored by and accountable to the Department of Health although the guidelines are created by independent committees of experts.

We were fortunate to sit representing the patients’ voice on their ectopic pregnancy and miscarriage guidelines and consider them to be a first step in the improvement of diagnosis, treatment and care for ectopic pregnancies. They are designed to be used by doctors rather than the general public so some of the words used may be very technical.

Greentop Guidelines

The Royal College of Obstetricians and Gynaecologists (RCOG) encourages the study and advancement of the science and practice of obstetrics and gynaecology and the majority of professionals in the field are members. It produces Greentop Guidelines.

The Ectopic Pregnancy Trust’s gold-standard for care is that any woman of childbearing age who has ectopic pregnancy symptoms should be considered to be pregnant until proven otherwise. We feel she should receive an ultrasound scan within 24 hours and follow up with beta hCG blood tests 48 hours apart if the scan is inconclusive. Early diagnosis improves treatment choice and reduces the emotional trauma associated with the condition and we feel this should always be taken into consideration.

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