Pregnancy of Unknown Location (PUL)

A pregnancy of unknown location (sometimes referred to also as an ‘inconclusive scan’) is when you have a positive pregnancy test but the pregnancy cannot be seen on ultrasound scan. It occurs in about 10% of the women who attend our Early Pregnancy Unit. If we are unable to see the pregnancy we cannot confirm that the pregnancy is in the right place within the uterus (womb), or that it is developing normally.

'Pregnancy of unknown location' is a medical label rather than diagnosis, and it is only used to describe the situation before the outcome (which may be a miscarriage, an ectopic pregnancy, or a healthy pregnancy) is known. We aim to confirm the location and wellbeing of your pregnancy as quickly as possible.

There are several reasons why we might not see a pregnancy on ultrasound:

1. It might be too early to see the pregnancy.

Urine pregnancy tests can now detect pregnancy very early. However, it will take about a week from when a pregnancy test becomes positive to when the pregnancy can be expected to be seen on ultrasound scan. Therefore, it may be that the pregnancy is too small to be seen on scan.

2. The pregnancy may have already miscarried.

If you have experienced heavy bleeding, the pregnancy may already have passed. However, a pregnancy test can still be positive because the pregnancy hormones (detected in the urine or blood test) take a while to gradually disappear. A urine pregnancy test can remain positive for up to three weeks after a pregnancy loss and you might continue to experience pregnancy symptoms, such as nausea or breast tenderness, during this time.

3. You may have an ectopic pregnancy.

An ectopic pregnancy occurs when the pregnancy has implanted outside of the womb. Ectopic pregnancies can be more difficult to find on an ultrasound scan than pregnancies that have implanted correctly within the womb. Ectopic pregnancies can be dangerous if they grow, as they can cause internal bleeding. Please see our information leaflet entitled 'ectopic pregnancy' for more details.

We will firstly need to take blood tests to measure two hormones: human Chorionic Gonadotrophin (hCG) and progesterone. Depending on the time you have your blood taken, we will call you with the results either the same day or the following morning. The blood tests may not give a final answer as to what is happening, but they will give us an indication what the most likely outcome is, and help us decide what to do next. We will explain what your results suggest when we call you.

Follow-up usually involves one of the following:

• A repeat blood test, usually after two days.
• A repeat ultrasound scan.
• A repeat home pregnancy test in one week.*
• Telephone follow up from our nursing team.*

*These will usually be suggested if the blood tests indicate that a miscarriage is more likely.

The timing of further appointments, blood or urine pregnancy tests is determined by the results of these.

When you have a scan, we will make sure that you are well enough to go home that day. However, it is important to remember that until we are able to make a definite diagnosis, it is possible that you have an ectopic pregnancy. It is therefore important that you attend hospital immediately if you develop worsening tummy pain, shoulder pain or have fainting episodes (please see our information on ‘ectopic pregnancy’).  

We also generally advise against travel, having sex, or doing strenuous exercise until your follow-up is complete and we are certain of the location, or resolution, of the pregnancy. You can ask the Early Pregnancy Unit team for further advice about potential risks based on your individual circumstances.

If you are having a miscarriage, you may experience heavy bleeding, and even pass something resembling pregnancy tissue. You do not need to seek urgent medical attention unless it is unmanageable or you feel unwell, but you should discuss your symptoms with us during follow-up.  

Most miscarriages are caused by a fault on a chromosome (a package of genes) within the cells of the developing pregnancy. This means that the pregnancy is not healthy and is not developing normally. This cannot be prevented, and it is not caused by anything you have done or not done. You may find our page on 'Early Miscarriage' helpful.

Having to attend an early pregnancy unit can be a worrying time and not knowing what is happening can make this even worse. Women and their partners can have different emotional reactions to what is going on. If these feelings are severe or if you feel that you need help in coming to terms with what you are experiencing it may help to talk to a professional and you should see your GP.

You may find some of the support organisations listed below helpful. You may also need more formal support or treatment, for which your GP can help or refer you.

You can also self-refer to your local counselling service, via “NHS Talking Therapies”. 

The Patient Advice and Liaison service (PALS) is a service that offers support, information and assistance to patients, relatives and visitors.

Telephone: 020 3447 9975

Email: PALS@uclh.nhs.uk

Address: PALS, Ground Floor Atrium, University College Hospital, 235 Euston Road, London, NW1 2BU

Early Pregnancy Unit 

Direct line: 020 3447 6515 (Please leave a voicemail)

Email: uclh.epunurses@nhs.net

Website: www.uclh.nhs.uk/gynaecology-diagnostic-and-treatment-unit

Opening Times:

Monday to Friday 09:00 - 12:30 and 14:00-16:30

Saturday and Sunday 09:00 - 12:30 (A&E referral only)

The EPU is located on the lower ground floor of the Elizabeth Garrett Anderson Wing. Follow signs to Clinic 3.