Pregnancy of Unknown Location: What It Means and What Happens Next

Medically reviewed by Dr. Bhimi Daimari, MBBS, MS (Obstetrics and Gynaecology) · Review date: 8 November 2026

Your pregnancy test is positive, you have a scan, and the doctor says they cannot see the pregnancy. Then you hear the words “pregnancy of unknown location”. It is a confusing and worrying place to be. This guide explains what a pregnancy of unknown location (PUL) really means, the four ways it can turn out, how the 48-hour hCG blood test works, the warning signs to watch for, and how to cope with the waiting.

What does “pregnancy of unknown location” mean?

It means exactly what it says: your body is making the pregnancy hormone hCG, so you are pregnant, but the scan cannot yet show where the pregnancy is. Doctors use this term so that nobody guesses too early, because the treatment depends completely on the location.

A PUL is common, especially in women who have an early scan because of bleeding or pain. Depending on how early the scan is done, between about 1 in 10 and 3 in 10 early pregnancy scans end up as a PUL at first.

Why can’t the pregnancy be seen?

• It is too early. A pregnancy sac usually becomes visible on a vaginal scan at around 5 weeks, when hCG is roughly 1,000 to 2,000 IU/L or more. If your dates are uncertain, you may simply be earlier than you think.
• The pregnancy has already ended. A very early miscarriage may have happened, sometimes with bleeding that looked like a period.
• The pregnancy is outside the womb. A small ectopic pregnancy may not be visible yet.
• Technical reasons: fibroids, body shape or the position of the womb can make the scan harder.

The four possible outcomes

Doctors follow a PUL until it falls into one of these groups. The numbers below are approximate ranges from studies of women in early pregnancy units; your own chances depend on your symptoms and hCG results.

Outcome	What it means	How often (approx.)
Failing PUL	The pregnancy is ending naturally. hCG falls and goes back to negative.	About half or more
Early pregnancy in the womb	Too small to see at first; seen on a later scan.	About 1 in 3
Ectopic pregnancy	Growing outside the womb, usually in a tube. Needs close care.	About 7 to 20 in 100
Persisting PUL	hCG stays at a similar level and the pregnancy is never seen.	A small number (about 2 in 100)

How the 48-hour hCG test works

The most important test in a PUL is a blood hCG measured twice, 48 hours apart. A single number cannot tell where the pregnancy is; the change between the two numbers is what helps. UK guidance (NICE) uses these rules:

• hCG rises by more than 63% in 48 hours: this suggests a developing pregnancy in the womb. You will usually be offered another scan in 7 to 14 days, or sooner once hCG is above the level where a sac should be seen (many units use about 1,500 IU/L). An ectopic pregnancy is still possible, so you should still watch for warning signs.
• hCG falls by more than 50% in 48 hours: this suggests the pregnancy is ending naturally. You will usually be asked to do a urine pregnancy test after about 2 weeks; if it is still positive, you should contact the clinic again.
• Anything in between (a small rise, a plateau or a small fall): this needs review by the clinic within 24 hours, because this pattern is more often seen with an ectopic pregnancy or a pregnancy that is failing.

Some hospitals also measure progesterone or use a computer risk model that combines the two hCG results. Whatever the method, the aim is the same: to keep you safe until the location is clear. Read more about hCG levels by week.

Warning signs while you wait

These can be signs of a rupturing ectopic pregnancy, which causes internal bleeding. It is rare, but it is the main reason you are being followed closely. Read about how much bleeding is normal in early pregnancy.

What happens next: the treatment options

What happens depends on which outcome your results point to:

• Pregnancy in the womb: normal pregnancy care continues once the sac and later the heartbeat are seen.
• Failing PUL: usually no treatment is needed. You check that hCG goes back to negative with a urine test.
• Ectopic pregnancy: depending on your symptoms, scan and hCG level, the options are careful waiting and monitoring (for small, stable ectopics with low and falling hCG), a medicine injection that stops the pregnancy growing (methotrexate), or keyhole surgery. Your doctor will explain which is safest for you.
• Persisting PUL: after discussion with a senior doctor, options may include continued monitoring, medicine, or a small procedure to check the lining of the womb.

How long does it take to get an answer?

Many women have an answer within a few days to 2 weeks. Some need several blood tests and more than one scan. It can feel slow, but each test makes the picture clearer. Keep all your appointments, even if you feel well or the bleeding has stopped.

Questions to ask your doctor

• What were my two hCG numbers, and what was the percentage change?
• When is my next blood test or scan?
• Which phone number do I call if I get pain or bleeding at night?
• Do I need an anti-D injection (if my blood group is Rh negative)?
• Can I travel, work or have sex while we are waiting?

Coping with the waiting

Not knowing whether your pregnancy is continuing is very hard. It is normal to feel anxious, sad or numb, and to swing between hope and fear. Things that help many women: bringing your partner or a trusted person to appointments, writing your results down, limiting late-night searching, and asking the clinic who you can call with questions. If the pregnancy ends, give yourself time to grieve; this is a real loss.

Will this affect my next pregnancy?

A PUL itself does not damage fertility. If it turns out to be a miscarriage, most women go on to have a healthy pregnancy later. If it is an ectopic pregnancy, ask your doctor about an early scan in your next pregnancy to check the location early. See also what causes miscarriage and missed miscarriage.

Can a pregnancy of unknown location become a healthy pregnancy?

Yes. This is the outcome many women hope for, and it does happen often. In studies from early pregnancy units, roughly 1 in 3 pregnancies of unknown location turn out to be a normal pregnancy in the womb that was simply too early to see on the first scan. These pregnancies usually show a good rise in hCG over 48 hours and a sac on the next scan, and most go on normally from there.

Even when a PUL ends in a miscarriage or an ectopic pregnancy, a successful pregnancy afterwards is the most common outcome. Most women who have an early miscarriage have a healthy pregnancy next time, and many women conceive naturally after an ectopic pregnancy, especially when one tube remains healthy.

What the guidelines say

UK guidance from NICE (NG126) and the Royal College of Obstetricians and Gynaecologists (RCOG), and European guidance from ESHRE, follow the same basic approach:

• A PUL is a temporary label, not a diagnosis, and should not be treated as an ectopic pregnancy just because nothing is seen.
• Women who are stable should be followed with serial hCG blood tests (usually 48 hours apart) and repeat transvaginal ultrasound.
• Treatment such as methotrexate should not be given before the location is known, unless a specialist decides it is needed for a persisting PUL.
• Every woman should leave with clear warning signs and a phone number to call day and night.

Sometimes falling hCG with nothing seen on the scan turns out to be a chemical pregnancy, the earliest kind of miscarriage.

Frequently Asked Questions

How rare is a pregnancy of unknown location?

It is not rare. It is one of the most common results of an early scan, especially in women scanned early because of bleeding or pain. Units that scan very early, or where scans are harder, report it more often; specialist units with experienced sonographers report it less often. Most PULs are resolved within days to weeks without any treatment.

How to manage pregnancy of unknown location?

Management is mostly careful follow-up: blood hCG tests, usually 48 hours apart, and a repeat scan when the hCG level is high enough to see a sac. On your side, it means keeping every appointment, keeping your phone on for results, staying within easy reach of a hospital, and going to the emergency department straight away if you get one-sided pain, shoulder-tip pain or feel faint. Medicine or surgery is only used once the cause is clear, or in special cases decided by a specialist.

What are the possible signs of an ectopic pregnancy at 4 weeks?

At 4 weeks many ectopic pregnancies cause no symptoms at all, apart from a positive test. When there are signs, they are usually mild: light or brown spotting, a dull ache or mild cramp on one side of the lower belly, or bleeding that is different from a normal period. Stronger pain, shoulder-tip pain and dizziness usually appear later, often between 6 and 8 weeks, and are an emergency.

What does “pregnancy of unknown location” mean?

In simple words: the hormone test says you are pregnant, but the scan cannot yet show where the pregnancy is. It is a working label that doctors use while they wait for more information, not an illness. Doctors keep using it until the pregnancy is seen in the womb, an ectopic pregnancy is found, or hCG falls back to negative.

Sources

• NICE NG126: Ectopic pregnancy and miscarriage: diagnosis and initial management
• Royal Cornwall Hospitals NHS Trust: Pregnancy of Unknown Location clinical guideline (2026)
• Barnhart K, van Mello NM, Bourne T, et al. Pregnancy of unknown location: a consensus statement of nomenclature, definitions, and outcome. Fertility and Sterility. 2011;95(3):857-866.
• ESHRE Working Group on Ectopic Pregnancy. Terminology for describing normally sited and ectopic pregnancies on ultrasound: ESHRE recommendations for good practice. Human Reproduction Open. 2020.

Medical disclaimer: This article is for general education only. It does not replace advice, diagnosis or treatment from a qualified doctor. If you have severe pain, shoulder-tip pain or feel faint, go to the nearest emergency department.