What is an ectopic pregnancy? Doctors explain.

An ectopic pregnancy occurs “when a fertilized egg implants outside the uterus,” Dr. Kimeshia Thomas, an obstetrician and gynecologist at USC Verdugo Hills Hospital, tells Yahoo Life.

It happens in 1 out of every 50 pregnancies, according to Johns Hopkins Medicine, making it one of the most common complications of pregnancy. Ectopic pregnancies can be life-threatening if left untreated.

Here’s what you need to know about them.

What exactly is an ectopic pregnancy?

An ectopic pregnancy occurs when a fertilized egg “implants in any location which is not the intended place” — namely, in the uterus — Dr. Mitchell Creinin, professor and director of family planning in the department of obstetrics and gynecology at the University of California Davis Health, tells Yahoo Life.

In the vast majority of cases — more than 90% — ectopic pregnancies occur in the fallopian tubes, according to the American College of Obstetricians and Gynecologists (ACOG). The fallopian tubes carry eggs from the ovaries to the uterus. But in some cases, the fertilized egg can get stuck along the way, which can happen if the tube is inflamed or misshapen, according to the Mayo Clinic.

However, that’s not the only location where an ectopic pregnancy can occur. “The uterus has upper corners — called the cornua— for which implantation here is not normal and is considered an ectopic pregnancy,” explains Creinin. “Also, if a pregnancy implants in the scar of a prior cesarean section, that is not in the uterine body, so that also is an ectopic pregnancy. These delineations are vitally important for patients, clinicians and legislators to understand, as we enter a...post-Roe era.”

Above all, Thomas says, “these are nonviable pregnancies” — meaning that the fertilized egg cannot survive — “and can become a medical emergency if they are not treated appropriately.” In fact, ectopic pregnancies are the most common cause of maternal death in the first trimester.

How would you know if you're experiencing an ectopic pregnancy?

With an ectopic pregnancy, most women will experience cramping or abdominal pain — typically on just one side of the lower belly — and vaginal spotting or bleeding, according to Thomas.

However, Creinin notes that “these signs are vague and are more commonly related to non-ectopic pregnancy diagnoses.” In other words, they can be missed or misdiagnosed. According to the American Academy of Family Physicians, between 40% to 50% of ectopic pregnancies are misdiagnosed.

“The most important issue for any person early in pregnancy with either of these symptoms is to discuss them with a clinician to figure out if an evaluation for ectopic pregnancy is indicated or not,” suggests Creinin.

If it’s indicated or if you’re concerned, your health care provider may perform a pelvic exam, do an ultrasound or check your blood for a pregnancy hormone called hCG (human chorionic gonadotropin), according to ACOG.

How is it treated?

Ectopic pregnancies are typically treated with medication — namely, methotrexate — or in some cases with surgery. “For tubal ectopic pregnancies, treatment can be with medications that dissolve the ectopic pregnancy tissue or with surgery,” explains Creinin. “The smaller the pregnancy, the more likely the medications can be used. Other ectopic pregnancies are more complex and may require medications, surgery or commonly, a combination of these treatments.”

With surgery, Thomas explains that it involves “removal of the pregnancy or affected fallopian tube” and is an option in certain circumstances, such as in “patients who cannot receive methotrexate, failed medical management” or for those who have experienced a rupture.

What happens if an ectopic pregnancy isn't treated?

An ectopic pregnancy is a “medical emergency,” says Thomas, which, if left untreated, can cause major internal bleeding.

“When a pregnancy implants in the correct location of the uterus, the uterine muscle is designed to be able to stretch/grow as the pregnancy develops,” explains Creinin. “Other organs, like the [fallopian] tube, cannot grow that way and will eventually burst.”

Creinin explains that the same will happen if the fertilized egg is implanted in the cervix, the corner of the uterus or even the ovary. “If left untreated, an ectopic pregnancy can result in life-threatening hemorrhage,” he says.

Women who have a ruptured ectopic pregnancy can "quickly become unstable and die,” says Thomas. She adds: “We take ectopic pregnancies very seriously, and emergency department physicians are well trained to notify ob-gyn specialists immediately if they are concerned that this may be occurring.”

Luckily, life-threatening hemorrhages caused by ectopic pregnancies are “very rare” in the U.S. today, says Creinin, “with less than 50 people dying from an ectopic pregnancy per year.” He adds: “This low rate is a benefit of relatively excellent access to care as compared to many developing countries, emergency medical systems, blood banks and availability of emergency surgery when needed.”

How does overturning Roe v. Wade affect ectopic pregnancy care?

With Roe v. Wade being overturned by the Supreme Court, some fear that ectopic pregnancy care in certain states could also be affected. Experts note that treatment of ectopic pregnancies is not considered to be an abortion. Even the American Association of Pro-Life Obstetricians stated that it “does not consider treatment of ectopic pregnancy by standard surgical or medical procedures to be the moral equivalent of elective abortion, or to be the wrongful taking of human life.”

Regardless, Thomas says that “managing an ectopic pregnancy is not a choice a woman makes based on their personal ideologies. It is a medical decision that they must make in collaboration with a physician. Treatment is a necessity to preserve the health of the pregnant person. The American College of Obstetrics and Gynecology, as well as the medical literature, have very clear guidelines on what an ectopic pregnancy is, how to diagnose it and how to treat it.”

But, given the increasing number of restrictions put on reproductive care in several states across the U.S., Creinin emphasizes that it is critical for clinicians “to act without concern for prosecution when an ectopic pregnancy is diagnosed.” He says that an ectopic pregnancy that is still growing “raises concerns for some physicians that any act to treat the patient is equivalent of abortion, which it is not. This lack of understanding and confusion" may "result in more patients dying unnecessarily.”

Want lifestyle and wellness news delivered to your inbox? Sign up here for Yahoo Life’s newsletter.