Extrauterine pregnancy: A pregnancy that is not in the usual place and is located outside the inner lining of the uterus. A fertilized egg settles and grows in any location other than the inner lining of the uterus. The large majority (95%) of extrauterine pregnancies occur in the Fallopian tube. However, they can occur in other locations, such as the ovary, cervix, and abdominal cavity.
An extrauterine pregnancy, also called an ectopic pregnancy, affects about 1 in 60 pregnancies. The term "ectopic" comes from the Greek "ektopis" meaning "displacement" ("ek", out of + "topos", place = out of place). The first person to use "ectopic" in a medical context was the English obstetrician Robert Barnes (1817-1907) who applied it to an extrauterine pregnancy: an ectopic pregnancy.
Ectopic pregnancies are frequently due to an inability of the fertilized egg to make its way through a Fallopian tube into the uterus. Most ectopic pregnancies occur in women 35 to 44 years of age. Risk factors predisposing to ectopic pregnancies include:
- Pelvic inflammatory disease (PID) which can damage the tube's functioning or leave it partly or completely blocked;
- Surgery on a Fallopian tube;
- Surgery in the neighborhood of the Fallopian tube which can leave adhesions (bands of tissue that bind together surfaces);
- Endometriosis, a condition in which tissue like that normally lining the uterus is found outside the uterus;
- A prior ectopic pregnancy;
- A history of repeated induced abortions;
- A history of infertility problems or medications to stimulate ovulation; and
- An abnormality in the shape of the Fallopian tube, as with a congenital malformation (a birth defect).
Pain is usually the first symptom of an ectopic pregnancy. The pain, often one-sided, may be in the pelvis, abdomen or even in the shoulder or neck (due to blood from a ruptured ectopic pregnancy building up under the diaphragm and the pain being "referred" up to the shoulder or neck). The pain is usually sharp and stabbing. Weakness, dizziness or lightheadedness, and a sense of passing out upon standing can represent serious internal bleeding, requiring immediate medical attention.
Diagnosis of an ectopic pregnancy includes a pelvic exam to test for pain, tenderness or a mass in the abdomen. The most useful laboratory test is the measurement of the hormone hCG (human chorionic gonadotropin). In a normal pregnancy, the level of hCG doubles about every two days during the first 10 weeks whereas in an ectopic pregnancy, the hCG rise is usually slower and lower than normal. Ultrasound can also help determine if a pregnancy is ectopic, as may sometimes culdocentesis, the insertion of a needle through the vagina into the space behind the uterus to see if there is blood there from a ruptured Fallopian tube.
Treatment of an ectopic pregnancy is surgery, often by laparoscopy today, to remove the ill-fated pregnancy. A ruptured tube usually has to be removed. If the tube has yet not burst, it may be possible to repair it.
The prognosis (outlook) for future pregnancies depends on the extent of the surgery. If the Fallopian tube has been spared, the chance of a successful pregnancy is usually better than 50%. If a Fallopian tube has been removed, an egg can be fertilized in the other tube, and the chance of a successful pregnancy drops somewhat below 50%.