A fertilized ovum usually travels down the fallopian tube and within a period of about five days, implants into the lining of the uterus. The cells of the developing zygote continuously multiply even as it moves down the tube. Tiny hair like “cilia” sweep the ovum down to the uterus where it embeds itself into the endometrium.
If motility through the tube or the environment within the tube is altered, or if the lumen of the tube is scarred or mishapen or narrowed, the ovum may simply get “stuck.” The developing zygote is programmed to continue to grow and find nourishment, but soon outgrows the tiny space within the tube. It may be retained within the tube, which results in scarring and occlusion but most often ruptures, breaking through maternal circulation and causing hemorrhage.
Women who are most at risk for ectopic pregnancy are those with previous tubal scarring, either from previous ectopic pregnancies or infection such as chlamydia, gonorrhea or complications of such infections such as pelvic inflammatory disease.
Because IUDs impact tubal motility, women who have them may be at increased risk.
Other factors associated with ectopic pregnancy may include:
- Previous tubal pregnancy or surgery
- Pelvic inflammatory disease (PID)
- Pelvic scarring
- Pelvic tumors
- Inadequate endometrium
- Deformities within the uterus
Other types of pregnancies may be referred to as “ectopic.” Any pregnancy which does not implant in the appropriate endometrial area of the uterus may be categorized as ectopic. If a pregnancy begins at the junction of the tube and upper uterus (interstitial), at the cervix or ovary or anywhere in the abdominal cavity, it is said to be an ectopic pregnancy.
Surprising to many women, is the fact that this is not an easy diagnosis. Many of the typical early pregnancy signs and symptoms may mimic those of an early ectopic pregnancy. The period is usually late but there may be some vaginal bleeding or spotting. Symptoms of pregnancy such as breast tenderness, nausea and fatigue may still be present. Some women develop pelvic cramping or abdominal pain; sometimes it is located on either side but may also be at the midline. As the pregnancy advances, shoulder pain or signs of blood loss such as dizziness or faintness may develop.
Even the physical exam may not be very helpful, especially in the early phases. A woman may have pain or tenderness during an exam, her cervix may be tender and the care provider may palpate a fullness or mass on one side or the other. However, all of these signs may be absent. It is possible to ignore early warning signs, only to have the pregnancy rupture causing significant life threatening hemorrhage.
Obstetric care providers caution all women to watch for pain and bleeding, as these are the hallmarks of an ectopic pregnancy. If there is a suspicion, lab tests and ultrasound are requested.
Human Chorionic Gonadotropin (Beta hCG) levels are drawn, although the amount of hCG found in ectopic pregnancy is variable. Low levels of beta HCG can be found in ectopic pregnancy. Certain levels have been found to be consistent with a healthy pregnancy at its expected gestational age. If a certain level of hCG is found and the pregnancy is still not visualized within the uterus, ectopic pregnancy or miscarriage is a strong possibility.
Serial blood counts may be performed to quantify blood loss and ultrasound is ordered to view the contents of the uterus, the gestational sac (if identified) and the pelvis. A skilled ultrasonographer is usually able to identify markers of ectopic pregnancy.
Treatment of ectopic pregnancy depends upon the mother’s condition, the gestational age of the pregnancy (size of the ovum) and whether or not rupture has occurred. Either surgical or medical treatment may be appropriate.
Medications may be administered, which abort the pregnancy safely with little threat to the mother’s life or future fertility. Methotrexate may be provided if the ovum is very small and unruptured. In cases of cervical, ovarian or abdominal pregnancy, surgery would be required. If the tube has ruptured, surgery to stop hemorrhage and remove (or rarely to repair) the tube is required.
The best protection against ectopic pregnancy is effective contraception and protection against sexually transmitted disease. If ectopic pregnancy is suspected, rapid diagnosis and treatment is essential to save lives and protect future fertility.