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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. Ectopic pregnancies occur from 1 in every 40 to 1 in every 100 pregnancies. This rate increased four-fold between 1970 and 1992. The incidence of ectopics is also higher is women over 35 and in women of African descent.

Most ectopic pregnancies result from scarring caused by previous tubal infection or tubal surgery. 30%- 50% of women with ectopic pregnancies have a medical history of salpingitis or 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. Ectopics can occur after assisted reproductive techniques such as IVF and GIFT were used to achieve pregnancy. In the Center for Disease Control’s (CDC) 2003 ART Report, 0.7% of cycles resulted in ectopic pregnancy.

Occasionally 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.

Symptoms of ectopic pregnancy can vary and include the following:

• 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

If rupture and hemorrhaging occurs before successfully treating the pregnancy, symptoms may worsen and include:

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

In the infertility population, early documentation of pregnancy with serum ß-hCG and ultrasound helps in diagnosing ectopic pregnancy. ?-hCG is produced by the trophoblast and in normal pregnancies doubles every two days in the first several weeks of pregnancy. Ectopic pregnancies have impaired ß-hCG production with a prolonged doubling time. Plateaued levels are most predictive of ectopic pregnancies.

Transvaginal ultrasound can document an intrauterine pregnancy earlier and can also distinguish between intrauterine and ectopic pregnancy. When serum ß-hCG levels are as low as 1000 mIU transvaginal USS should be able to identify an intrauterine pregnancy (gestational sac) if the pregnancy is normal. Another advantage of the ultrasound is the ability to detect adnexal cardiac activity in an ectopic pregnancy. This is useful to determine whether surgery is necessary or whether a non-surgical approach is sufficient.

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 ?-hCG s, blood counts and liver function tests.

In the event of rupture the risk of internal bleeding and/or hemorrhage and possible shock necessitates the need for a laparotomy to stop the immediate blood loss, remove the products of conception and repair and or remove the affected fallopian tube or the surrounding tissue. In non-emergency cases mini-laparotomy or laparoscopy are the common surgical treatments. They are less invasive and require minimal hospitalization.

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

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)

References:
ASRM Practice Committee Report: Early diagnosis and management of ectopic pregnancy 2001.
Available at: http://www.asrm.org/membersonly/practice/ectopicpregnancy.PDF

Breen J. A 21 year survey of 654 ectopic pregnancies. Am. J. Obstet. Gynecol. 1970; 106:1004.

CDC Assisted Reproductive Technology Report. Available at: http://www.cdc.gov/ART/ART2003/slideshow/slideshow06.htm

Lipscomb G et al. Predictors of success of methotrexate treatment in women with tubal ectopic pregnancies. NEJM 1999; 341:1974.

Marchiano D. Ectopic pregnancy. Available at: http://www.nlm.nih.gov/medlineplus/ency/article/000895.htm

Walker J. Guidelines on diagnosing ectopic pregnancy. Available at: http://www.ectopic.org/medical_information/diagnosis_guidelines.htm