Sometimes a pregnancy cannot be seen on scan at all even though there is pregnancy hormone present in your blood. We would want to check for a pregnancy of unknown location or ectopic pregnancy in this case.
An ectopic pregnancy is when we can see the pregnancy though it is growing outside the uterus possibly in the fallopian tube or ovary.
A pregnancy of unknown location (PUL) is when we cannot see a pregnancy anywhere on scan though there is pregnancy hormone present in your blood.
These situations need investigated because if a pregnancy is growing in the fallopian tube then the tube may rupture causing internal bleeding. This can present as abdominal pain especially to the one side, shoulder tip pain and with or without vaginal bleeding and medical advice should be sought.
Further bloods (BHcG) would be required
You would be offered further blood tests/scans or possibly to go to theatre for a laparoscopy (camera) to look to see if we can see the pregnancy. If an ectopic pregnancy was identified the piece of fallopian tube with the pregnancy within would be removed, the laboratory would then confirm that you have had an ectopic pregnancy which is no longer continuing.
Sometimes if a PUL is suspected then you will be offered a methotrexate injection. The methotrexate works by stopping the pregnancy cells from growing by blocking the folate which they require to grow. Management by methotrexate involves further appointments and blood samples to ensure that the pregnancy hormone levels have fallen to a non pregnant level. Depending on how high your blood levels were initially this could involve a few weeks worth of visits.