Monday, October 15, 2007

Ectopic (tubal) pregnancy

DEFINITION — Ectopic pregnancy occurs when a developing embryo implants at a site other than the inside wall of the uterus. A brief overview of early pregnancy may be helpful in understanding ectopic pregnancy.

Normal pregnancy — A woman's reproductive system includes the uterus, two ovaries, two fallopian tubes, and the vagina. The fallopian tubes are narrow tubes that link the ovaries and uterus (show figure 1). Once a month, an egg is released by one of the ovaries (ovulation) and travels down the fallopian tube to the uterine cavity. In women undergoing treatment for infertility, more than one egg may be released by the ovary. If the egg is fertilized in the fallopian tube by the male's sperm, pregnancy begins.

Once joined, the egg and sperm begin to rapidly develop new cells. This group of cells, called the embryo, normally implants on the inner wall of the uterus, called the endometrium. Once implanted, the embryo continues to grow and also forms the placenta, the organ that provides a blood supply for the developing embryo.

Ectopic pregnancy — In an ectopic pregnancy, the developing embryo does not implant on the endometrial wall, but instead attaches to some other surface. Ninety eight percent of the time, that surface is within fallopian tubes. An ectopic pregnancy in a fallopian tube is sometimes called a tubal pregnancy.

Very rarely, the developing embryo will attach to another site such as the cervix or an ovary. It can also implant at the site where the fallopian tube and uterus join; this is called an interstitial pregnancy, or on the abdominal wall. Rarely in twin pregnancies, one embryo implants in the uterus and the other implants at an ectopic location. This rare event is called a heterotopic pregnancy and occurs more commonly in women undergoing infertility treatments.

Embryos that do not implant in the uterine wall are generally unable to develop normally. In addition, an ectopic pregnancy can cause rupture of the organ on which they are implanted, typically the fallopian tube. Rupture can result in severe internal bleeding, shock, and possibly death of the mother. Fortunately, the ability to diagnose, monitor, and treat ectopic pregnancy reduces the risk of life-threatening complications.

RISK FACTORS — A number of factors increase the risk for ectopic pregnancy. They can be divided into strong, moderate, and weak risk factors.

Strong risk factors Abnormalities of the fallopian tubes — If the fallopian tubes are damaged or abnormal as a result of previous infection or surgery, tumors, or rarely, due to malformations present since birth, there is an increased risk of ectopic pregnancy. Surgery to reconstruct the fallopian tube (to improve a woman's chances of becoming pregnant) can increase the risk of ectopic pregnancy, although preexisting tubal damage poses an even greater risk. Previous ectopic pregnancy — Women who have had one ectopic pregnancy have an increased risk for having another. The underlying tubal disorder that led to the first ectopic, and the effects of treating the first episode increase the risk for another ectopic pregnancy. In-utero diethylstilbestrol (DES) exposure — Women whose mothers took DES while pregnant are more likely to have abnormalities of the fallopian tubes and are at increased risk for an ectopic pregnancy.

Moderate risk factors Previous genital infections — Pelvic infection with gonorrhea or chlamydia is a major cause of tubal problems and increases the risk of ectopic pregnancy. Infertility — The incidence of ectopic pregnancy is higher in the infertility population, mostly due to the increased incidence of tubal abnormalities in these women. Fertility drugs also appear to alter tubal function by their effects on hormones and may be associated with the increased risk in this population. Multiple sexual partners — Having more than one sexual partner is associated with an increased risk of pelvic infection, and therefore an increased risk of ectopic pregnancy.

Weak risk factors Smoking — Cigarette smoking around the time of conception increases the risk of ectopic pregnancy; the risk increases with the number of cigarettes smoked. This risk may be the result of impaired immunity in smokers, which predisposes them to pelvic infection or impaired functioning of the fallopian tubes. Vaginal douching — Regular vaginal douching is associated with increased risk of both pelvic infections and ectopic pregnancy. Douching is never recommended under any circumstance. Age — Having a first sexual encounter at a young age (less than 18) slightly increases the risk of ectopic pregnancy.

Other risk factors In vitro fertilization (IVF) — IVF, a fertility treatment in which a woman's egg is fertilized outside the body and then placed in her uterus, is associated with an increased risk of both ectopic and heterotopic pregnancy. Tubal sterilization — Tubal sterilization is a surgical procedure in which the fallopian tubes are either cut, ligated, or coagulated. It is commonly known as having the "tubes tied," and is performed to prevent future pregnancies. Rarely, tubal sterilization fails and pregnancy can result. Women who become pregnant after tubal sterilization have a higher risk for ectopic pregnancy. Intrauterine contraceptive devices — Women who become pregnant while using an intrauterine contraceptive device (IUD) are at higher risk for ectopic pregnancy than women using other forms of contraception or no contraception.

SYMPTOMS — Symptoms, when they occur, appear early in pregnancy and often before the woman realizes she is pregnant. They include abdominal pain, amenorrhea (absence of a period), and vaginal bleeding, which may be minimal. Symptoms of pregnancy (such as breast tenderness, frequent urination, or nausea) may also be present.

However, over 50 percent of women have no symptoms until rupture occurs. Following rupture of the tube, the woman may experience severe pain and profound hemorrhage (bleeding). Lightheadedness or dizziness may occur first, followed by a drop in blood pressure, fainting, and shock. If there is severe bleeding, shock can progress to death.

Sometimes, the embryo is expelled by the fallopian tube before rupture occurs. This is called a "tubal abortion." Once expelled, the embryonic tissue may degenerate, or it may reimplant in the abdominal cavity or on the ovary. Tubal abortion can be accompanied by severe intra-abdominal bleeding requiring surgical intervention, or by minimal bleeding that does not require treatment.

Ectopic pregnancies can sometimes resolve on their own, but the incidence of spontaneous resolution is not known. Because an ectopic pregnancy poses such great risk to the mother, it should be treated as soon as possible after it is diagnosed.

DIAGNOSIS — Transvaginal ultrasound and a blood test that measures the pregnancy hormone, hCG (human chorionic gonadotropin), are used to diagnose ectopic pregnancy. Ultrasound technology uses sound waves to visualize structures within the body. In a transvaginal ultrasound, the ultrasound transducer is inserted into the woman's vagina allowing clearer visualization of the uterus and other pelvic organs. It can generally detect intrauterine pregnancies that are 5 to 6 weeks along. Ultrasound is most useful for identifying an intrauterine gestation. An extrauterine pregnancy will be visualized in only 16 to 32 percent of women, therefore a negative pelvic ultrasound (that is, no intrauterine or extrauterine gestation is seen) does not exclude the possibility of an ectopic pregnancy. hCG (human chorionic gonadotropin) is a substance secreted by the developing embryo/placenta. The hCG blood level is measured to confirm a pregnancy and can be used to monitor the progress of the early pregnant state.

Ectopic pregnancy is diagnosed if the ultrasound detects a fetal heart beat or an embryo that is outside of the uterus. Since ectopic pregnancies may not be detected by ultrasound, the hCG level is also measured. If the hCG is above a threshold level (usually 1500 mIU/mL), but no pregnancy is seen with ultrasound, an ectopic pregnancy is suspected. A value below this level may indicate either an ectopic pregnancy or early intrauterine pregnancy. When this happens, the ultrasound and hCG are repeated every few days until an ectopic pregnancy can be either confirmed or ruled out.

Women with moderate or strong risk factors for ectopic pregnancy, and those who conceived after IVF, are often monitored with ultrasound and blood testing after their first missed period to ensure early detection and treatment of a potential ectopic pregnancy.

TREATMENT — An ectopic pregnancy must be treated to stop its growth; observation or "watch and wait" treatment is never recommended as the life of the mother is at risk if treatment is delayed. Treatment is started as soon as a diagnosis of ectopic pregnancy is confirmed. Ectopic pregnancy may be treated with medication or surgery.

Medical management — The majority of unruptured ectopic pregnancies are treated with methotrexate, which inhibits the production of new cells and halts further growth of the embryo. It is given in an intramuscular injection. After the injection, the woman may experience abdominal pain or cramps, which can usually be controlled with acetaminophen (Tylenol®). Nonsteroidal antiinflammatory drugs should be avoided due to the risk of an interaction between NSAIDs and methotrexate.

hCG levels are monitored once weekly until the level has fallen to less than 10 mIU/mL. In 20 percent of women, a second dose of methotrexate is necessary; this is recommended if the day 7 hCG level has not fallen by at least 25 percent. In some cases, multiple doses of methotrexate are required.

Methotrexate is most successful in women who have an ectopic pregnancy without symptoms (eg, pain), and whose hCG level and ultrasound results fall within specified limits. When used in appropriate situations, treatment with methotrexate is successful 92 to 98 percent of the time (show table 1). If treatment with methotrexate is unsuccessful, tubal rupture can occur. This complication can be avoided with close monitoring and surgical management, if needed.

Surgical management — Surgery is sometimes recommended as treatment for ectopic pregnancy. Indications include: Ruptured ectopic pregnancy, especially when the woman's blood pressure has fallen and she is unstable. A woman who is unable or unwilling to return for monitoring after methotrexate therapy. A woman who would normally be a candidate for medical treatment, but who could not reach a hospital (due to lack of transportation or distance to an appropriate healthcare facility) in the event of tubal rupture during medical therapy.

Surgery may be performed using a laparoscopic approach or through an abdominal incision. In laparoscopy, special instruments are inserted into the abdomen through a few small incisions. These instruments are used to visualize and remove the ectopic pregnancy and control bleeding. In an abdominal procedure, the surgeon opens the abdomen using a single larger incision and then directly visualizes and removes the ectopic pregnancy.

Surgical management may include removal of the fallopian tube (called total or partial salpingectomy) or may remove the ectopic pregnancy and repair the tube (called salpingostomy). Leaving the tube in place is an option for some women and is preferred if the woman would like to become pregnant in the future. Some conditions require removal of the tube, including uncontrolled bleeding, recurrent ectopic pregnancy in the same tube, a severely damaged tube, or a large tubal pregnancy. It may also be performed in women who have completed childbearing.

In a small number of women treated surgically, embryonic tissue may still be present after surgery and cause the hCG level to remain elevated. A dose of methotrexate may be given if this occurs.

WHERE TO GET MORE INFORMATION — Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two patients are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.

This discussion will be updated as needed every four months on our web site (www.patients.uptodate.com). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information.

A number of web sites have information about medical problems and treatments, although it can be difficult to know which sites are reputable. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable. National Library of Medicine

(www.nlm.nih.gov/medlineplus/healthtopics.html)
The Nemours Foundation

(http://kidshealth.org)
Planned Parenthood Federation of America

(www.plannedparenthood.org)
Mayo Clinic

(www.mayoclinic.com)


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Use of UpToDate is subject to the Subscription and License Agreement. REFERENCES 1. Ankum, WM, Mol, BWJ, Van Der Veen, F, Bossuyt, PMM. Risk factors for ectopic pregnancy: a meta-analysis. Fertil Steril 1996; 65:1093.
2. Yao, M, Tulandi, T. Current status of surgical and non-surgical treatment of ectopic pregnancy. Fertil Steril 1997; 67:421.
3. Tulandi, T. Current protocol for ectopic pregnancy. Contemp Obstet Gynecol 1999; 44:42.
4. Practical and current management of tubal and nontubal ectopic pregnancy. Curr Probl Obstet Gynecol Fertil 2000; 23:94.

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