In an ectopic pregnancy, a fertilized egg implants and begins growing outside the uterus, most commonly inside a fallopian tube. Because the fallopian tube is not designed to support a growing pregnancy, the embryo cannot develop normally, and the situation can become life-threatening without treatment. Roughly 6.7 million ectopic pregnancies occurred worldwide in 2019, making it one of the most common serious complications of early pregnancy.
Why the Embryo Implants in the Wrong Place
After fertilization, an embryo normally travels through the fallopian tube and reaches the uterus within three to four days. If the tube is blocked or damaged, it can’t move the embryo along, so the embryo implants in the tube’s lining instead. About 95% of ectopic pregnancies happen in the fallopian tubes, though in rare cases the embryo can implant on the ovary, in the abdominal cavity, or in the cervix.
The most common cause of tubal damage is a previous pelvic infection, particularly from sexually transmitted infections like chlamydia or gonorrhea. These infections can scar the delicate inner lining of the tube, destroying the tiny hair-like structures (cilia) that sweep the embryo toward the uterus. Endometriosis, previous pelvic surgery, and a history of appendicitis can also damage the tubes in ways that trap an embryo.
Who Is at Higher Risk
About half of all ectopic pregnancies are linked to some degree of tubal damage. But certain factors raise your risk significantly. A previous ectopic pregnancy increases the odds of it happening again by more than sixfold. A history of pelvic inflammatory disease roughly triples the risk. Infertility, whether treated or untreated, is associated with about three times the usual risk as well.
Smoking is another well-established risk factor. The chemicals in tobacco appear to impair the tube’s ability to move the embryo, slowing its transit enough that it implants before reaching the uterus. Using an intrauterine device (IUD) makes pregnancy extremely unlikely in the first place, but in the rare event that conception occurs with an IUD in place, the pregnancy is more likely to be ectopic.
Early Symptoms and When They Appear
At first, an ectopic pregnancy can feel exactly like a normal one. You may have a missed period, breast tenderness, and nausea. A home pregnancy test will come back positive because the body still produces pregnancy hormones.
As the embryo grows in the confined space of the tube, symptoms become more noticeable, typically between weeks four and twelve of gestation. The first warning signs are usually light vaginal bleeding that looks different from a normal period and a dull or sharp pain on one side of the pelvis. The pain may come and go at first, then become more persistent. Some people also experience pain in the lower back or abdomen that feels different from typical menstrual cramps.
What Happens If a Tube Ruptures
The most dangerous complication is a ruptured fallopian tube. As the embryo grows, it stretches the thin tubal wall until the tissue tears open, causing internal bleeding. This is a medical emergency.
The signs of rupture are sudden, severe abdominal or pelvic pain, often described as sharp or stabbing. Because blood from the rupture can pool under the diaphragm and irritate the nerve that runs to the shoulder (the phrenic nerve), many people experience an unexpected pain in the right shoulder that has no obvious cause. This referred shoulder pain is one of the hallmark warning signs of a ruptured ectopic pregnancy. You may also feel an unusual urge to have a bowel movement as blood collects in the pelvis.
As internal bleeding continues, symptoms of shock set in: dizziness, fainting, a rapid heartbeat, and a drop in blood pressure. Without emergency treatment, a ruptured ectopic pregnancy can be fatal. It remains one of the leading causes of maternal death in the first trimester.
How It’s Diagnosed
Diagnosing an ectopic pregnancy involves two main tools: blood tests that measure pregnancy hormone levels and a transvaginal ultrasound. In a healthy early pregnancy, hormone levels (specifically beta-hCG) follow a predictable pattern, rising by at least 49% over 48 hours when initial levels are low. When those levels rise more slowly than expected, plateau, or drop by less than 21% over two days, an ectopic pregnancy becomes a strong possibility.
On ultrasound, doctors look for a pregnancy sac inside the uterus. If hormone levels are high enough that a normal pregnancy should be visible in the uterus but nothing is there, the pregnancy is likely ectopic. Sometimes the ectopic pregnancy itself can be seen in the tube, though in many cases the diagnosis is made by ruling out a normal intrauterine pregnancy rather than directly visualizing the ectopic one.
Treatment Options
There is no way to move an ectopic pregnancy into the uterus. The pregnancy cannot survive, and treatment focuses on ending it safely before complications develop. The approach depends on how far along the pregnancy is, whether the tube has ruptured, and your overall health.
Medication
When an ectopic pregnancy is caught early, before rupture and while the embryo is still small, a single injection of a medication can stop the pregnancy’s cells from growing. Over the following weeks, the body gradually reabsorbs the tissue. You’ll need follow-up blood tests to confirm that hormone levels are dropping back to zero, which can take several weeks. During this time, you may experience some abdominal pain and cramping as the tissue resolves.
Surgery
If the ectopic pregnancy is further along, if the tube has already ruptured, or if medication isn’t appropriate, surgery is necessary. Most often this is done laparoscopically through small incisions. Surgeons either remove just the ectopic tissue while preserving the tube, or remove the affected tube entirely. The decision depends on how much damage the tube has sustained, whether the other tube is healthy, and your plans for future pregnancies.
When one tube is removed, pregnancy is still possible through the remaining tube. However, if both tubes are severely damaged, in vitro fertilization (IVF) becomes the primary path to future pregnancy, since it bypasses the tubes entirely.
Recovery and Future Pregnancies
Physical recovery from surgical treatment typically takes a few weeks for laparoscopic procedures, longer if emergency open surgery was required. Emotional recovery often takes longer. An ectopic pregnancy is a pregnancy loss, and grief is a normal response regardless of how early it was detected.
Most people go on to have healthy pregnancies afterward, but the risk of another ectopic pregnancy is elevated. Having one ectopic pregnancy raises the odds of a second one by more than six times compared to someone with no history. Because of this increased risk, early monitoring in any subsequent pregnancy is important. An early ultrasound can confirm the pregnancy is in the uterus and provide reassurance during a time that often carries significant anxiety.