An pregnancy of unknown location (PUL) is when you have a positive pregnancy test but we cannot see the pregnancy on ultrasound.
What does this mean?
There are three possible reasons:
- The pregnancy is too early to see on the scan. Home pregnancy testing kits are extremely sensitive and can sometimes detect the pregnancy hormone just a few days after conception. However, a pregnancy may not be seen on ultrasound until about 3 weeks after conception (at least 5 weeks from your last period). This results in women attending the Early Pregnancy Unit with a pregnancy that is probably in the correct place but is too early for us to see.
- An early miscarriage has occurred. The pregnancy may have started but may have stopped growing (a miscarriage)
- The pregnancy is outside the uterus (womb) most commonly in the fallopian tube. This is called an ‘ectopic’ pregnancy. It is the least likely possibility but if ignored an ectopic pregnancy is potentially life-threatening. Until we can see a pregnancy inside the womb we cannot exclude an ectopic pregnancy
Ectopic pregnancy is one that is growing outside the uterus (womb). Often, an ectopic pregnancy grows in one of the Fallopian tubes. Around 1% of pregnancies are ectopic. An ectopic pregnancy is very serious and can be life-threatening.
An ectopic pregnancy can happen to any woman. Some conditions make it more likely. These include:
- having had an ectopic pregnancy in the past
- diseases that affect the fallopian tubes
- having had abdominal surgery in the past
- a history of pelvic inflammatory disease (PID)
- an intrauterine device in place such as the copper “coil” or Mirena
- older age