Ectopic pregnancy

An ectopic pregnancy is one in which the fertilized ovum is implanted in any tissue other than the uterine wall. Most ectopic pregnancies occur in the Fallopian tube (so-called tubal pregnancies), but implantation can also occur in the cervix, ovaries, and abdomen.

Overview

In a normal pregnancy, the fertilized egg enters the uterus and settles into the uterine lining where it has plenty of room to divide and grow. In a typical ectopic pregnancy, the embryo does not reach the uterus, but instead adheres to the lining of the Fallopian tube. As the embryo implants and grows, the tube becomes stretched and inflamed, causing increasing pain in the pregnant woman. If left untreated, the affected Fallopian tube will likely burst, causing gynecologic hemorrhage and endangering the life of the woman. Only 2% of ectopic pregnancies occur outside of the fallopian tubes. About 1% of pregnancies are in an ectopic location.

Causes

Cilia damage and tube occlusion

Hair-like cilia located on the internal surface of the Fallopian tubes carry the fertilized egg to the uterus. Damage to the cilia, or blockage of the Fallopian tubes is likely to lead to an ectopic pregnancy.

Women with pelvic inflammatory disease (PID) have a high occurrence of ectopic pregnancy. This results from the build-up of scar tissue in the Fallopian tubes, causing damage to cilia and possibly tube occlusion.

Tubal surgery, such as tubal ligation (or the reversal thereof), is also likely to cause cilia damage. And because ectopic pregnancy is treated with tubal surgery, a history of ectopic pregnancy increases the risk of future occurrences.

A higher rate of ectopic pregnancies has also been found in women who have previously had one or more abortions.

Excessive estrogen and progesterone

High levels of estrogen and progesterone increase the risk of ectopic pregnancy because these hormones slow the movement of the fertilized egg through the Fallopian tube. The use of progesterone-secreting intrauterine devices (IUDs), the morning-after pill, and other hormonal methods of contraception often result in high estrogen and progesterone concentration and may increase the risk of ectopic pregnancy. Ectopic pregnancies are seen more commonly in patients undergoing infertility treatments.

Other

Patients are at higher risk for ectopic pregnancy with advancing age. Also, it has been noted that smoking is associated with ectopic risk. Vaginal douching has been shown to increase ectopic pregnancies.

Symptoms

Patients with an ectopic pregnancy typically have:

Lower back, abdominal, or pelvic pain.
There may be cramping or even tenderness on one side of the pelvis.
The pain is of recent onset, and often getting worse.
Vaginal bleeding may be present.
Low serum hematocrit (due to loss of blood)
Elevated serum human chorionic gonadotropin (due to pregnancy)

Ectopic pregnancy is noted that it can mimic symptoms of other diseases such as appendicitis, other gastrointestinal disorder, problems of the urinary system, as well as pelvic inflammatory disease and other gynecologic problems.

Diagnosis

An ectopic pregnancy has to be suspected in any woman with lower abdominal pain and/or unusual bleeding who is sexually active and whose pregnancy test is positive. And abnormal rise in blood hCG levels may also indicate an ectopic pregnancy. An ultrasound examination may reveal the abnormal location of the pregnancy, show evidence of intraabdominal bleeding, or reveal an empty uterine cavity when normally the pregnancy should have been detectable within the uterus.

A laparoscopy or laparotomy can also be performed to visually confirm ( and then remove) an ectopic pregnancy within the abdominal or pelvic cavity.

Nontubal ectopic pregnancy

2% of ectopic pregnancies occur in the ovary, cervix, or intraabdominally. Transvaginal ultrasound examination is usually able to detect a cervical pregnancy. An ovarian pregnancy is differentiated from a tubal pregnancy by the criteria set by Spiegelberg. While a fetus of ectopic pregnancy typically cannot be salvaged, the case of an occasional abdominal pregnancy has been the very rare exception to this rule. In such a situation the placenta sits on the intraabdominal organs and the peritoneum and has found sufficient artery access (either the renal (kidney) or hepatic (liver) artery) to support a fetus to viability. Such a fetus will have to be delivered by laparotomy. However, the vast majority of abdominal pregnancies require intervention well before fetal viability because the risk of hemorrhage.

The successful ectopic abdominal pregnancy leads to theoretic possibility of deliberate human male pregnancy, but would carry the same risks of hemorrhage.

Treatment

Nonsurgical treatment

Early treatment of an ectopic pregnancy with the drug methotrexate has proven to be a viable alternative to surgical treatment since 1993. If administered early in the pregnancy, methotrexate can disrupt the growth of the developing embryo causing the cessation of pregnancy.

Surgical treatment

If hemorrhaging has already occurred, surgical intervention is necessary to halt blood loss and reduce the risk of shock. Surgeons use laparoscopy or laparotomy to gain access to the pelvis and can either incise the affected Fallopian and remove only the pregnancy (salpingostomy) or remove the affected tube with the pregnancy (salpingectomy). The first successful surgery for an ectopic pregnancy was performed by Robert Lawson Tait in 1883. The chance of future pregnancy depends on the status of the tube(s) that are left behind, but is decreased. Often, patients may have to resort to IVF to achieve a successful pregnancy.

Footnotes

Medical emergencies | Obstetrics | Pregnancy

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