Ectopic pregnancy occurs when a fertilized egg implants in tissue outside of the uterus, and the placenta and fetus begin to develop there. The most common site is within a fallopian tube. However, ectopic pregnancies can rarely occur in the ovary, the abdomen, and in the lower portion of the uterus (the cervix).

Ectopic pregnancies are usually caused by conditions that obstruct or slow the passage of a fertilized ovum (egg) through the fallopian tube to the uterus. This may be caused by a physical blockage in the tube. Ectopic pregnancy may also be caused by failure of the zygote (the cell formed after the egg is fertilized) to move down the tube and into the uterus.

Most cases are a result of scarring caused by previous tubal infection or tubal surgery. Up to 50% of women with ectopic pregnancies have a medical history of salpingitis or PID (pelvic inflammatory disease). Some ectopic pregnancies can be traced to congenital tubal abnormalities, endometriosis, tubal scarring and kinking caused by a ruptured appendix, or scarring caused by previous pelvic surgery and prior ectopic pregnancies. In a few cases, the cause is unknown.

On occasion, a woman will become pregnant after elective tubal sterilization. The risk of an ectopic pregnancy occurring in this situation may reach 60%. Women who have had surgery to reverse previous tubal sterilization in order to become pregnant also have an increased risk of ectopic pregnancy when reversal is successful.

The administration of hormones, specifically estrogen and progesterone, can slow the normal movement of the fertilized egg through the tubal epithelium and result in implantation in the tube. Women who become pregnant despite using progesterone-only oral contraceptives have a 5-fold increase in the ectopic pregnancy rate.

Women who become pregnant while using a progesterone-bearing IUDs also have an increased risk of ectopic pregnancy. Ectopic pregnancy rates for those who become pregnant despite non-medicated IUD are 5%, while the rate for medicated IUD users who become pregnant despite the device is 15%. Note that these rates only refer to percents of the tiny proportion of women who become pregnant while using these methods -- they do not refer to women who have once used these methods and later become pregnant, or to the percent of women who become pregnant while using these methods.

The "morning after pill" (emergency contraception) has been linked to several cases of ectopic pregnancy.

Ectopic pregnancies occur from 1 in every 40 to 1 in every 100 pregnancies. This rate increased four-fold between 1970 and 1992.

Increased risk is associated with women who have a history of salpingitis or PID, tubal surgery of any type (including tubal ligation and its reversal), or prior ectopic pregnancy.

• Lower abdominal or pelvic pain
• Mild cramping on one side of the pelvis
• Amenorrhea (cessation of regular menstrual cycle)
• Abnormal vaginal bleeding (usually scant amounts, spotting)
• Breast tenderness
• Nausea
• Low back pain

• Severe, sharp, and sudden pain in the lower abdominal area
• Feeling faint or actually fainting
• Referred pain to the shoulder area

A pelvic examination may reveal uterine adnexal (Fallopian tube or ovary region) tenderness.

• There is usually a positive pregnancy test.
  • Urine HCG (qualitative) tests may be falsely negative in up to 17.5% of them.
  • In contrast, serum HCG (quantitative) tests have only a 2% incidence of false-negative results.
• A hematocrit test may be normal or decreased.
• The white blood count may be normal or increased.
• A culdocentesis may be performed to determine if free blood is present in the abdomen.
• An ultrasound (transvaginal ultrasound or pregnancy ultrasound) illustrates an empty uterus. Products of conception may be evident elsewhere.
• A laparoscopy or a laparotomy may be necessary for adequate diagnosis.
• A D and C may be indicated to rule out a nonviable intrauterine pregnancy.

• Serum progesterone -- a value of 25ng/mL or more is, 98% of the time, associated with a normal pregnancy in the uterus, while a value of less than 5ng/mL indicates that the pregnancy, regardless of location, is not going to be successful.

In the event that pelvic organ rupture has occurred because of the ectopic pregnancy, internal bleeding or hemorrhage may lead to shock. This is the first symptom of nearly 20% of ectopic pregnancies.

Shock is an emergency condition. Initial treatment may be keeping the woman warm, elevating her legs, and administering oxygen. Treatment with intravenous fluids and sometimes a blood transfusion is performed as soon as possible.

Surgical laparotomy is performed to stop the immediate loss of blood (in cases in which rupture has already occurred), or to confirm the diagnosis of ectopic pregnancy, remove the products of conception, and repair surrounding tissue damage. In some cases, removal of the involved fallopian tube may be necessary.

In non-emergency cases, mini-laparotomy or laparoscopy are the most common surgical treatments. Such procedures have similar outcomes. However, they are less invasive and are available at a lower cost because they require minimal hospitalization or outpatient treatment.

Non-surgical (medical) management for ectopic pregnancies without suspected immediate danger of rupture is being implemented in many medical centers . In such cases, methotrexate is administered with careful outpatient monitoring of the woman and serial quantitative HCGs, CBCs, and liver function tests.

About 85% of the women who have experienced one ectopic pregnancy are later able to achieve a normal pregnancy. A subsequent ectopic pregnancy may occur in 10 to 20% of cases. Some women fail to become pregnant again, while others become pregnant and spontaneously abort during the first trimester.

The maternal death rate from ectopic pregnancy in the U.S. has decreased in the last 30 years to less than 0.1%.

• Rupture, with resulting hemorrhage leading to shock and the need for blood transfusion, is the most common complication. Death from rupture is rare.
• Infertility occurs in 10 to 15% of women who have experienced an ectopic pregnancy.

A woman who has an early pregnancy, or who thinks she might be pregnant and has symptoms (especially lower abdominal pain or abnormal vaginal bleeding) should notify her health care provider. Ectopic pregnancy can occur in any woman who is fertile and sexually active, regardless of contraceptive use.

Forms of ectopic pregnancy, other than tubal, are probably not preventable. However, tubal pregnancies, which make up the majority of ectopic pregnancies, may be prevented in some cases by avoiding those conditions that might cause scarring of the fallopian tubes. Such prevention may include:

• Avoiding risk factors for PID -- multiple partners, intercourse without a condom, and sexually transmitted diseases (STDs)
• Early diagnosis and adequate treatment of STDs
• Early diagnosis and adequate treatment of salpingitis and pelvic inflammatory disease (PID)

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Nielsen CL, Miller L. Ectopic gestation following emergency contraceptive pill administration. Contraception. 2000 Nov;62(5):275-6.