In a normal pregnancy, the ovum (egg) from the mother is fertilized by the sperm from the father to form a zygote in the female fallopian tube (a tube leading from the ovary connecting to the uterus). This zygote divides and moves into the uterus to implant in the walls of the uterus.
In an ectopic pregnancy, the fertilized zygote divides and implants outside of the uterus, the most common location being the fallopian tube (96% of all ectopic pregnancies).
These pregnancies do not reach maturity due to the unfavorable conditions for growth and pose a risk to the mother as they may rupture and cause excessive bleeding and shock.
The other common locations for ectopic pregnancy are the ovary, cervix and pelvic cavity.
Risk Factors for Ectopic Pregnancy
- Previous Sexually Transmitted Infections (STI) and Pelvic Inflammatory Disease (PID): these infections can lead to scarring of the fallopian tubes which hamper the movement of the dividing zygote.
- Previous Ectopic Pregnancy
- Tubal ligation: This is considered a permanent method of contraception. However, in rare cases, the tubes may rejoin partially with residual scarring allowing fertilization of the egg without free movement into the uterus.
Symptoms of Ectopic Pregnancy
Complications of Ectopic Pregnancy
- Rupture: The most severe and serious complication is rupture of the ectopic with bleeding. The mother is at risk for a hypovolemic shock from blood loss into the abdominal cavity. This may even be fatal.
- Scarring of the fallopian tube
- Repeat ectopic pregnancy
DIAGNOSIS OF ECTOPIC PREGNANCY
The diagnosis is established with a combination of lab investigations and imaging.
- Physical Examination: The pelvic examination generally reveals tenderness in the cervix and surrounding structures.
- Positive urine pregnancy test
- Blood testing for Beta-HCG: This is a hormone that is released during pregnancy. In a normal pregnancy, the levels are generally higher and rise rapidly everyday compared to an ectopic pregnancy.
- Ultrasound: this is an imaging study using sound waves to visualize internal structures. In a normal pregnancy, a ‘gestational sac’ is visible within the uterus by the sixth week of pregnancy. The absence of this gestational sac in the uterus or the presence of the sac elsewhere in the abdomen (tubes, ovary) establishes the diagnosis. Two types of methods may be used- a pelvic ultrasound uses a probe placed on the lower abdomen and a transvaginal ultrasound uses a probe in the vagina to visualize structures.
TREATMENT OF ECTOPIC PREGNANCY
The treatment mode depends on the location and time of identifying ectopic pregnancy.
- When found early with a small ectopic, medicines alone may be adequate in clearing the pregnancy. Methotrexate injection is the treatment of choice in this situation.
- In case of large ectopics, medicines alone may cause severe blood loss and surgery is required to remove the ectopic pregnancy. Laparoscopic or open surgery may be done.
- In case of a ruptured ectopic pregnancy, emergency surgery is done by opening up the abdomen. Fluids are given intravenously to maintain blood pressure. Blood transfusions may be needed as well. The site of the rupture is located and removed after bleeding has been controlled.
- Tulandi T. Ectopic pregnancy: Clinical manifestations and diagnosis. https://www.uptodate.com/contents/search. Accessed April 6, 2019.
- Tulandi T. Ectopic pregnancy: Epidemiology, risk factors, and anatomic sites. https://www.uptodate.com/contents/search. Accessed April 6, 2019.
- Frequently asked questions. Pregnancy FAQ 0155. Ectopic pregnancy. American College of Obstetricians and Gynecologists. April 6, 2019.