An ectopic pregnancy is a pregnancy that implants outside of the uterus. Ectopic pregnancies account for one to two percent of all conceptions. The majority (95%) of ectopic pregnancies occur in the fallopian tube. However, less commonly an embryo may implant in the cervix, ovary or even very rarely in the wall of the abdomen.
Causes of ectopic pregnancy
Women with damaged fallopian tubes are more likely to develop an ectopic pregnancy. In fact, 50 percent of ectopic pregnancies are associated with some degree of tubal disease. Tubal disease may be the result of a bacterial pelvic infection. Bacteria which are commonly associated with tubal disease are usually transmitted sexually and include gonorrhea and chlamydia.
Tubal disease may also occur as a result of inflammation in the abdomen from endometriosis or appendicitis. Surgery involving the fallopian tube will also increase the chance of a tubal ectopic pregnancy. This is true for surgeries designed to help women attempt pregnancy such as opening a blocked tube or women who have attempted to prevent pregnancy with a tubal sterilization procedure. Occasionally, an ectopic pregnancy can occur in a woman without any obvious risk factors for tubal disease.
Symptoms of ectopic pregnancy
Early in a pregnancy, a woman may be unaware that a pregnancy is an ectopic. In fact, early symptoms of an ectopic pregnancy may mimic those of a normal pregnancy. Some women with an ectopic pregnancy may have light vaginal bleeding or spotting as a symptom. When a pregnancy is six to eight weeks along, some women may experience varying degrees of pelvic or lower abdominal pain. Often this pain can be localized to one side or another but this is not always true. Pelvic pain and vaginal bleeding are also symptoms that can occur during a miscarriage. Sometimes, it can be very difficult to distinguish between an ectopic pregnancy and a miscarriage.
Diagnosis of ectopic pregnancy
Transvaginal ultrasound is probably the single most reliable and non-invasive way to diagnose an ectopic pregnancy. It is not infallible, however. In order to understand how an ectopic pregnancy is diagnosed it is important to understand a little bit about how any pregnancy is diagnosed.
After fertilization of the egg in the fallopian tube, the newly formed embryo will normally travel down the fallopian tube into the uterus. Some of the cells of the growing embryo will produce a hormone called human chorionic gonadotropin or simply hCG. Once the embryo implants, the hCG being produced is absorbed into the mother’s circulation. These hCG levels can be detected by performing a blood test. Once the hCG levels become high enough, that can also be detected in the urine. This forms the basis for the modern home pregnancy test.
A normally developing pregnancy will produce hCG levels in increasing amounts. The rate of increase can be determined over a number of days. If a physician detects that the hCG levels are not rising at an appropriate rate, then he may become suspicious that the pregnancy may be abnormal in some way. Unfortunately, there is some overlap between normal and abnormal pregnancies. In other words, occasionally, a normal pregnancy may show a slowly increasing hCG or an abnormal pregnancy (miscarriage or ectopic) may demonstrate a normal or fast rising hCG.
In a normally developing pregnancy, it is possible to predict when the pregnancy should be visible on ultrasound. In our practice, we know that once an hCG levels reaches 2000, that a gestational sac should be visible in the uterus on transvaginal ultrasound. If a pregnant woman has an hCG level that is over 2000 and no gestational sac is visible on ultrasound, it is assumed that the patient may have an ectopic pregnancy and she is given special precautions. In only 5% of cases of ectopic pregnancy, can the ectopic be seen directly in the fallopian tube. Usually, it is the absence of a visible pregnancy in the uterine cavity that leads to the diagnosis of an ectopic pregnancy.
Other signs that may be identified on ultrasound can increase the suspicion for the pregnancy of an ectopic. For example, the uterine lining tissue can be seen and measured on transvaginal ultrasound. Frequently, women with an ectopic pregnancy will have a much thinner uterine lining than women with a normally developing pregnancy or with an impending miscarriage. Fluid in the abdominal cavity could be a sign of internal bleeding that occurs as a complication of an ectopic pregnancy.
Progesterone is a hormone that is produced from the ovary after ovulation. In the absence of pregnancy, the progesterone levels produced by the ovary will decline and eventually result in a woman starting her menstruation. If a pregnancy is present, however, the hCG from the pregnancy causes the ovary to continue the production of progesterone and the thus the woman “misses” her period. Progesterone levels in the bloodstream rise very early in the course of a pregnancy. Low levels of progesterone are often associated with an abnormally developing pregnancy, such as an ectopic pregnancy or an impending miscarriage. Progesterone levels are not very helpful in diagnosing an ectopic pregnancy in women who are undergoing treatment with fertility medications since these medications can boost the progesterone levels and thus give a falsely reassuring result.
Dilation and Curettage (D&C)
If a physician has determined that a pregnancy is non-viable but is not certain if it is located in the uterus (an impending miscarriage) or if it is located in the fallopian tube, a minor surgical procedure can be used to help distinguish between the two conditions. This operation, known as a D&C (dilation and curettage), can be performed under anesthesia either in the hospital or as an outpatient procedure. During this procedure, the physician will gently dilate the opening to the uterus called the cervix until a thin suction catheter can be inserted. Using suction, the contents of the uterus are removed. The uterine contents can be immediately sent to a pathologist to observe under a microscope.
This method for diagnosing an ectopic pregnancy depends on the fact that it is exceedingly rare for a woman to have an ectopic pregnancy and a pregnancy in the uterus at the same time. Therefore, if pregnancy tissue is found by the pathologist from the uterine D&C, this will almost always rule out the possibility of an ectopic pregnancy. The advantage to this method is that if uterine pregnancy tissue is found, it spares the patient from having to have undergo invasive surgery in which the physician looks directly into the abdomen. If no pregnancy tissue is found in the uterus, than the physician can proceed with further surgery while the patient is still under anesthesia.
Laparoscopy for the diagnosis and treatment of ectopic pregnancy
Laparoscopy is an outpatient surgical procedure requiring general anesthesia. Once the patient is asleep, the abdomen is filled with carbon dioxide and a thin telescope is placed into the abdomen through the belly button. The incision needed to insert the laparoscope is usually 1 cm or less. A camera is attached to the laparoscope allowing the physician to view the inside of the abdomen on a monitor. Additional small incisions (5 mm or less) can be made, usually on the right and left side near the pubic hair line. The physician can place instruments through these additional incisions to allow completion of various tasks such as holding the fallopian tube for better visualization. During the laparoscopy, the physician will first look for the presence of blood in the abdomen. This would be the first clue for an ectopic pregnancy. Next, he will attempt to visualize each fallopian directly. An ectopic pregnancy will usually appear as a swollen in the area in the fallopian tube. Sometimes, a very early or small ectopic can be hard to detect in a fallopian tube. If an ectopic pregnancy is identified, it can be treated at the same time (see Surgical Treatment below).
TREATMENT OF ECTOPIC PREGNANCY
Medical treatment of ectopic pregnancy
If an ectopic pregnancy is diagnosed early enough, medication can be used to eliminate the pregnancy tissue from the fallopian tube. The medication used is called methotrexate. Methotrexate (MTX) is an anti-metabolite that has been used in other fields of medicine such as the treatment of psoriasis, some types of cancer, and rheumatoid arthritis. MTX inhibits an enzyme that is a necessary to make and repair DNA inside of cells. Cells which divide rapidly such as cancer cells, bone marrow, fetal cells, cell from the digestive system and cells of the urinary bladder are more sensitive to MTX. Since pregnancy tissue is very rapidly growing its growth is going to be interrupted by MTX.
To be a candidate for methotrexate therapy, a pregnant woman needs to be in stable condition with no evidence of internal bleeding or severe pain. The pregnancy should be very early. Studies have shown that advanced tubal pregnancies do not respond as well to treatment with methotrexate. Women with large ectopic pregnancies, rapidly rising and/or high levels of hCG (> 10,000 IU/L) are less likely to respond to methotrexate therapy and, therefore, may be considered candidates for surgical treatment.
Methotrexate is given as a single intra-muscular shot or as a series of shots and pills over several days. Most of the side effects that have been reported from the use of methotrexate have not occurred in women being treated for ectopic pregnancy which usually only requires a single dose. Most of the side effects have been seen from treatment of other problems that may require higher doses or regimens that are given over the course of several weeks.
- Gastrointestinal disturbance: Some of the people who take MTX will experience one or more of the following symptoms: nausea, diarrhea, vomiting or ulcers in the mouth. This may result in dehydration. Symptoms do resolve when treatment is stopped.
- Blood and Bone marrow: MTX may cause anemia (low red blood cell count), leukopenia (low white blood cell count), and or thrombocytopenia (low platelet count). Low platelet counts can result in spontaneous bleeding. To determine whether is a candidate for MTX, she should have a simple blood test to ensure that she does not have any of these problems beforehand. She should also be monitored after MTX has been given to follow any decreases in these levels.
- Liver: MTX has the potential for causing temporary or permanent damage to liver cells. Simple blood tests should be given before MTX is given to ensure that she does not have measurable liver damage beforehand.
- Neurologic: MTX has caused confusion, irritability, seizures and coma to occur in some patients.
- Pulmonary (Lung): Development of a dry non-productive cough can be a sign of a potentially serious problem known as pulmonary fibrosis.
- Kidney: MTX can rarely result in kidney failure.
- Skin: Occasionally, patients taking MTX may develop severe skin conditions that might rarely be fatal. Reactions have been seen after even single doses.
There are no known long-term side effects from use of methotrexate.
Most early ectopic pregnancies can be successfully treated with methotrexate, often leaving the tube open. If methotrexate is successful, the hCG levels measured in the blood will begin to decline in four to five days. Eventually, the hCG levels should decline to zero over the next two to six weeks. If the hCG levels do not fall, methotrexate treatment may be repeated or the pregnancy may be removed surgically. A patient may experience some abdominal pain for a few days due to the resorption of the ectopic pregnancy. Women should limit sun exposure during treatment, as methotrexate can cause sensitivity to sunlight and sunburn may occur. When being treated with methotrexate, women should not drink alcohol or take vitamins containing folic acid (folate).
Surgical Treatment of ectopic pregnancy
Until recently, ectopic pregnancies were usually treated by removal of the entire fallopian tube. This required making an incision in the abdomen that was several centimeters long (open surgery or laparotomy) and resulted in patients being admitted to the hospital postoperatively for several days.
Today, open surgery is rarely performed for an ectopic pregnancy. It would typically be reserved for emergency situations in which the patient is unstable or thought to have life threatening internal bleeding from an ectopic pregnancy that has ruptured. Women who have had multiple ectopic pregnancies are also candidates to have their tubes removed.
The current gold standard for surgical treatment of an ectopic pregnancy is to perform the procedure laparoscopically. Preservation of fertility is a main objective in the modern treatment of an ectopic pregnancy. The reproductive surgeon can visualize the swelling in the fallopian tube and make an incision in the side of the tube over the swollen area. The pregnancy tissue can be removed through the incision leaving the remainder of the tube intact. This type of conservative tubal surgery is called a salpingostomy. The fallopian tube subsequently heals on its own. In most instances, after the tube has healed, it remains patent and able to produce another pregnancy.
The main disadvantage of this type of conservative surgery is that in some cases, residual ectopic pregnancy tissue may be left behind. For this reason it is very important to monitor a woman’s hCG levels after surgery to ensure they decrease all the way until negative. If residual ectopic tissue is detected, further treatment using MTX or repeat surgery to remove the tube is required.
There are other types of surgical procedures that are less commonly employed for the treatment of an ectopic pregnancy. A partial salpingectomy (sometimes called a segmental resection) is when the surgeon removes a segment from the middle of a fallopian tube that contains the ectopic pregnancy. The beginning and ends of the tube are left intact. This type of surgery is not preferred since it requires a second surgical procedure to reconnect the two parts of the tube again. A segmental resection may be needed if there is persistent bleeding of a tube or there is a large fear of leaving residual ectopic tissue behind.
Outcomes after ectopic pregnancy
The two main objectives in the treatment of ectopic pregnancy are to save the life of the woman who has the ectopic pregnancy and to preserve her fertility. Unfortunately, there is an increased chance of being infertile after an ectopic pregnancy. In addition, the chance of having another ectopic pregnancy is increased. It is thought that ectopic pregnancies occur due to damage to the fallopian tube. This same underlying damage can also make it more difficult to become pregnant. In this case, the infertility was present before the ectopic. In addition, treatment of the ectopic itself, whether by medication or surgery, can leave damage behind and therefore worsen infertility.
Fortunately, over half of women who experience an ectopic pregnancy will have a live born baby sometime in the future. It is extremely important for women who have had an ectopic pregnancy to be closely monitored whenever they believe they may be pregnant again. Monitoring should be performed initially with blood tests for hCG levels and then with ultrasound. Monitoring should continue until a definite intra-uterine pregnancy can be verified.
Prevention of ectopic pregnancy
The only way to prevent an ectopic pregnancy with 100% certainty is to avoid becoming pregnant. Even surgery that removes the fallopian tube does not completely eliminate the risk for an ectopic. This is due to the fact that there is a small portion of the tube that runs through the wall of the uterus and connects the uterine cavity to tube outside of the uterus. Even when the tube is removed, this small segment remains. An ectopic which occurs in this area is called an isthmic or cornual ectopic.
IVF can reduce the chances for ectopic pregnancy in those women who are at high risk. In-vitro fertilization is a technology in which eggs are removed from the ovaries and fertilized outside of the body. The embryos are then placed directly into the uterus. Only about 5% of pregnancies in women with a history of ectopic will be an ectopic with in vitro fertilization. This is compared to about 15-20% of pregnancies conceived without in vitro fertilization.