A normal-looking scan does not rule out an ectopic pregnancy
In an ectopic pregnancy the embryo attaches somewhere outside the uterus. It affects fewer than 2 per cent of pregnancies, yet it accounts for roughly 6 to 13 per cent of deaths among women in the first trimester. Up to one in ten affected women have no symptoms at all.
The classic signs are abdominal pain and vaginal bleeding, but fewer than half of affected women have both. Symptoms can mimic appendicitis, miscarriage, ovarian torsion or a urinary infection, and heavy bleeding without a scan or hormone test may be mistaken for miscarriage. If the pregnancy ruptures, internal bleeding can cause shock; some women then find lying flat painful and prefer to stay upright.
In a tubal pregnancy, the fertilised egg lodges in the fallopian tube instead of being swept to the uterus by tiny hair-like cilia. Damage to those cilia is a leading suspect: scar tissue from pelvic inflammatory disease, often caused by chlamydia, harms them, and smoking is linked to higher risk. Other risk factors include endometriosis, earlier tubal surgery, infertility and assisted reproduction, yet in one-third to one-half of cases no risk factor is found.
Wealthy nations record roughly 11 to 20 cases for every 1,000 live births, rising as high as 4 per cent among people using assisted reproductive technology. A previous tubal pregnancy lifts the chance of another to about 10 per cent. Outcomes have improved in wealthy countries but often remain poor in the developing world.
Transvaginal ultrasound picks up at least 90 per cent of cases, and a gestational sac with a heartbeat inside the tube is highly specific. But a scan that seems to show a normal pregnancy in the uterus is not conclusive, because a pseudosac, a fluid collection in the uterine cavity, appears in up to 20 per cent of women, and a heterotopic pregnancy is also possible. Treatment usually removes the embryo or the tube, and the drug methotrexate works as well as surgery in some cases. Losing one tube still leaves future pregnancy possible.
Source: Ectopic pregnancy
