What causes ectopic pregnancy?

The fallopian tubes carry an egg from an ovary towards the uterus. Scarring, narrowing or blockage can slow or stop this movement. Pelvic inflammatory disease can damage the tube, and previous surgery or an earlier ectopic pregnancy may also affect its shape or function. Sometimes no clear cause is found.

Most ectopic pregnancies occur in a fallopian tube, although implantation can happen elsewhere outside the uterine cavity. The pregnancy cannot develop normally in that location, so assessment is needed even when symptoms are mild or absent.

If you have a positive pregnancy test and pain or bleeding, contact a maternity or gynaecology service promptly. A clinician may arrange pregnancy-hormone blood tests and an ultrasound; very early pregnancies can need repeat assessment because the location may not yet be visible.

Do not blame yourself. An infection such as pelvic inflammatory disease can be treated, but treatment cannot reverse established tube scarring. Read about [Ectopic Pregnancy](/conditions/ectopic-pregnancy/) and [Pelvic Inflammatory Disease](/conditions/pelvic-inflammatory-disease/).

Seek emergency help for sudden or severe one-sided abdominal pain, shoulder-tip pain, fainting, marked dizziness, weakness or heavy vaginal bleeding during pregnancy. These can indicate internal bleeding and need immediate assessment.

Ask where the pregnancy appears to be, whether repeat blood tests or ultrasound are needed, and which symptoms should send you to emergency care. You can also ask whether a previous infection, operation or ectopic pregnancy changes your follow-up plan.