ectopic pregnancy
Meaning of ectopic pregnancy: A positive pregnancy test alongside an empty uterus on ultrasound is the combination that raises the question before symptoms make it obvious.
Definition of ectopic pregnancy
An ectopic pregnancy is one that implants and begins developing outside the cavity of the uterus, most often inside a fallopian tube. Tissue elsewhere cannot support a growing pregnancy, so it cannot proceed normally, and the surrounding structure can tear as the pregnancy expands. That risk of internal bleeding is what makes it time sensitive.
Why can it not continue?
The lining of the uterus is built for the task. It thickens with each cycle, it can grow a blood supply capable of supporting a placenta, and the muscular wall around it stretches enormously across months. A fallopian tube can do none of that. It is a narrow muscular tube a few millimeters across, its wall is thin, and it does not expand. A pregnancy implanting there erodes into the wall as it grows and eventually splits it. The tube carries a generous blood supply, so a rupture can bleed rapidly into the abdomen. That sequence, rather than the pregnancy itself, is the danger, and it is the reason an ectopic pregnancy is treated as urgent once suspected rather than observed.
Where do they implant?
| Site | Notes |
|---|---|
| Fallopian tube | The great majority, most often in the wider outer portion |
| Where the tube passes through the uterine wall | Uncommon and harder to identify, with thicker muscle around it |
| Ovary | Rare |
| Cervix | Rare, with a blood supply that makes bleeding hard to control |
| Abdominal cavity | Rare, and the one location where a pregnancy has occasionally continued much longer, though with substantial risk |
Anything that damages or slows the tube raises the risk, including previous infection of the tubes, a previous ectopic pregnancy, tubal surgery and endometriosis. Most ectopic pregnancies nonetheless occur in people with no identified risk factor at all. Extrauterine pregnancy means exactly the same thing.
How is it identified?
Three strands are combined. A pregnancy test establishes that a pregnancy exists. Measurement of the pregnancy hormone in blood, usually repeated after a short interval, shows whether the level is climbing the way a healthy pregnancy inside the uterus would. Ultrasound looks for where the pregnancy actually sits. Very early on it may be too small to see anywhere, so the combination carries more weight than any single result: a hormone level high enough that a pregnancy inside the uterus ought to be visible, with nothing seen there, points strongly toward an ectopic location. One-sided pain and vaginal bleeding are common but neither universal nor specific, since both also occur in early miscarriage and in a molar pregnancy.
Also known as
Used in a sentence
The patient's one sided pelvic pain and abnormal hormone levels prompted urgent evaluation for a possible ectopic pregnancy.
Good to know
A ruptured ectopic pregnancy carries a risk of significant internal bleeding, which is why the condition is treated as a time sensitive diagnosis once suspected, in contrast to the routine monitoring of a pregnancy developing normally within the uterus.
Word origin
Where “ectopic pregnancy” comes from
From Greek ektopos, meaning out of place, formed from ek-, meaning out of, and topos, meaning place.